2017 hottest summer in California history; Cut-off low may bring widespread thunderstorms

Filed in Uncategorized by on September 9, 2017 2,162 Comments

Overview of recent all-time record California heat

2017 was the warmest (or near-warmest) summer on record over most of the Western U.S. (NOAA/NCDC)

2017 brought extraordinary summer heat to California. While record-breaking early-season heatwaves largely spared the immediate coastal areas (but brought endless weeks of searing triple-digit heat to interior areas), extreme temperatures extended all the way to the beaches over the past couple of weeks.

The late summer and early autumn months are traditionally warmest of the year in coastal California, as the marine layer tends to become suppressed and offshore winds occasionally allow hotter air to encroach from the east. But the late August and early September heatwave that California just endured was on an entirely different level than those historically experienced–breaking (and, in many cases, shattering) temperature records of all kinds. Countless daily (and monthly) temperature records were set statewide, and this heatwave continued the already record-breaking streak of 100+ degree days across much of the Central Valley. Overnight temperatures stayed well above average daytime highs in many places, and new all-time “warmest minimum” records were set. Quite a few coastal or near-coastal California cities matched or exceeded their all-time temperature records for any month–an impressive list that spans from the North Coast (Eureka) to the central coast (San Luis Obispo) and apparently even includes (amazingly) the Farallon Islands in the midst of California’s cold oceanic upwelling zone. Easily the most amazing statistic during this extraordinary event was the fall of downtown San Francisco’s all-time temperature record, where the observed 106 degrees surged past the previous hottest temperature (103) in 147 years of record keeping.

It might not be a surprise, therefore, that summer 2017 was officially California’s hottest on record (and much of the Labor Day heatwave actually fell out outside of the formal June-August definition of “summer”). In fact, 2017 broke (by a considerable margin) the previous record set…just last year, in 2016. Indeed, this year once again puts an exclamation point on a sustained, long-term warming trend over the past century in California. Increasing frequency and intensity of extreme heatwaves is one of the clearest hallmarks of our warming climate, and it’s likely that “extreme” temperatures like those experienced this summer will become fairly routine in just a few decades.

California has experienced a sustained long-term warming trend in summer, and 2017 was the warmest season on record. (NOAA/NCDC)

 

Unusually widespread thunderstorm outbreak possible across California

An offshore cut-off low will be in a favorable position to produce relatively widespread thunderstorm activity. (NCEP via tropicaltidbits.com)

A slow-moving cut-off low pressure system is currently setting up shop off the Southern California coast, and has the potential to bring some very active weather to certain parts of the state over the next 5 days. Mountain and desert thunderstorms have already been quite active over the past few days, but beginning on Sunday convective development is likely much closer to (and perhaps including) the coast. In fact, convective parameters for late tomorrow afternoon for much of Southern California and the Central Coast are quite impressive, with able mid-level instability, sufficient column water vapor, and even some large-scale ascent forced by diffluent flow east of the offshore low.

With all of these ingredients in place, numerous thunderstorms will likely develop over the mountains of Southern California tomorrow afternoon, at least a handful of which will sustain themselves as they move east to west over the coastal plain and even offshore. At least a few of these storms may be quite strong (or even severe), bringing intense downpours along with possible hail and gusty winds. This, tomorrow could be a pretty active weather day even in places that rarely see this kind of vigorous thunderstorm activity.

An offshore jet streak will provide dynamical support for thunderstorms over the SoCal Bight on Sunday. (NCEP via tropicaltidbits.com)

There is at least a modest risk of flash flooding in interior areas hit by strong storms, and some localized issues could even occur outside of the mountains. It’s actually possible that thunderstorms may be more widespread tomorrow across portions of SoCal (including Los Angeles County) than they were during the recent “Lidia” tropical remnant event. (On a related note, if you haven’t checked out this video showing extraordinary webcam footage of the highly localized but quite damaging Santa Barbara microburst last week, you really should. Also, this one.).

On Monday and Tuesday, the thunderstorm threat will shift northward to encompass most of the rest of California–even including the Bay Area and Central Valley.

The GFS is showing fairly widespread precipitation accumulations over most of California over the next 5 days. (NCEP via tropicaltidbits.com)

Scattered thunderstorms may ultimately occur uniformly over much of NorCal as moisture and instability will be present virtually everywhere. This sort of synoptic set-up–with a fairly deep offshore cut-off low and modest amounts of late monsoonal moisture–is reminiscent of the sort of pattern that has historically caused spectacular early autumn lightning displays over parts of California. Hopefully, this event will be associated with enough wetting rainfall to avoid numerous wildfire strikes, but given the time of year and the antecedent heat/dryness, this event will probably pose a significant fire weather threat.

Later next week, the cut-off low will finally move inland and perhaps bring a final round of isolated showers and thunderstorms to a fairly broad area (perhaps even the coast), though coverage and intensity should be less than earlier in the week. After that, quieter weather conditions will likely return.

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  • Yolo Hoe

    Made it down to 50F overnight and still sitting there this morning in far southwest Davis — putting on light gloves for morning ride

    • CHeden

      56F overnight at my place in Cottonwood. Partly cloudy and hazy. Expecting highs in the 80’s again. Perfect for getting the Winter prep chores underway.

      • Yolo Hoe

        Patiently awaiting our first Box of Rain — though must say this weather is mighty fine for the chores you note — once the haze gets flushed out we’ll be living the early autumn dream — what are the pattern dynamics required for Sacramento Valley haze clearing?

        • CHeden

          Enough Pacific wind to mix down to the surface, mostly. Cold air advection aloft to de-stabilize things a bit would help too.

          • Yolo Hoe

            Thanks!

  • CHeden

    Sorry if someone already posted this:
    The monthly CPC ENSO forecast, released on the 14th, has issued a La Nina advisory.
    “There is an increasing chance (~55-60%) of La Niña during the Northern Hemisphere fall and winter 2017-18.”
    Here is the link to the advisory: a must read as a prelude to Winter.
    http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/
    Interesting to note that as recently as the 11th, the weekly update still had La Nada conditions preferred…so this change in thinking by the models/CPC just occurred in the last few days. The advisory mentions the depth of the colder water, and coupled with the observed continuing/acceleating? downward trend, the models now think that weak-moderate La Nina solution is preferred, peaking somewhere around December/Jan time frame.
    How interesting. https://uploads.disquscdn.com/images/41810d9b2f41141f7e0dfd4d4f1a1d16f555d7d60c31540fb89ce6ceee9c187d.gif

  • Joey B.

    It’s 49 degrees in Lafayette as of 7:30 this morning. Coldest low temperature we’ve had in a while. Fall is coming!

  • Thunder98 (Santa Maria Valley)

    Pleasant September weather for next several days. Notice that the lows are much cooler than it was in the past couple weeks. Lows in the upper 40’s possible as well?

    https://i.imgur.com/Y675pcN.png

  • CHeden

    As I mentioned below, the change in thinking by the CPC on the La Nina is quite dramatic. The top image of probabilities is from August and the bottom from the latest Sept. report.
    https://uploads.disquscdn.com/images/bc26869a3282adbfad0ab4032233e4023e19ff686deb3c1d915674a7759b1923.gif https://uploads.disquscdn.com/images/4050529770cb691ab504d87e0b6e16100a2a41356e5ff2a8f5a97d43c0e97893.gif

    • Pfirman

      Why do the line graphs remain unchanged?

      • Admode (Susanville)

        They are running averages based on what has already happened.

    • RanDog

      CHeden, where did you get that Early-Sep graphic? The CPC weekly update (http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf) still has the Aug version.
      Thanks

      • CHeden

        Check out the monthly discussion. The weekly update should be out today or tomorrow, and SHOULD be updated with a La NIna Advisory per the 9-14 report.

  • Great Winter of 2017 (SMC)

    54 as the low this morning, been in the mid to low 50s for the last 3 days!

  • Great Winter of 2017 (SMC)

    I don’t know if it’s just me, but it seems most long range forecasts for Fall and Winter from meteorology agencies and NOAA have a bias towards warmer and drier conditions in CA. Anyone know why this is?

    • jstrahl

      Maybe because we’re gonna have warmer and drier conditions? 🙂

      • jstrahl

        Proof in the pudding: Farmer’s Almanac predicting cooler and wetter than normal winter, above average mountain snows, for California. Sure sign of warm, dry winter. https://www.almanac.com/weather/longrange/CA/Los%20Angeles

        • Thunderstorm

          The migratory birds agree already arriving on the wetlands by me. Also 13 hurricanes already in the Atlantic, and the blue blob is expanding.

    • SlashTurn (Santa Barbara)

      Anyone with wind in their jaws can put out a seasonal forecast, especially letter agencies. Truth is no one has a clue and I love it…

      • I disagree. It takes supercomputers not just hot air 🙂

        • GR

          Except that they have been running simulations for over 50 years. There must be literally trillions, and they can err as decisively now as 1917. A wondrous thing.

    • happ [Los Angeles]

      My sense is that rain prospects remain unclear especially after the past 3 years of an El Nino that wasn’t and bountiful AR events since then. I am concerned about a warm winter since that can be the results of prolonged ridging

    • Great Winter of 2017 (SMC)

      You all have valid points

    • SoCal Al (El Monte-SGV)

      I look at it this way. Over the last few years our SoCal weather predictions have been 180 out from what was forecasted, so I’ll go with the thinking of the opposite from what’s predicted for us.

  • CHeden

    We can only hope we see something similar to this in a few months…only a little bit further south with a little more moisture. https://uploads.disquscdn.com/images/0ca5c123bae63073c8f03ecc3b46cf34ef777664aaf9a6d3f50965bc42463103.jpg

  • Rainmaker (San Jose)

    you know what I miss about the days with 100 degree temps? That I only had to run the dryer for like 5 minutes and my clothes would be dry.

    • I’ll ask my wife. She’ll give me one of those ‘you’ve been on that blog again, aren’t you!’ looks.

  • Great Winter of 2017 (SMC)

    Out of NOWHERE Otis in the Pacific went from being forecast to stay as a depression, then to a tropical storm and now likely a Major Hurricane after rapidly intensifying! Beautiful example of how hard it is to forecast a tropical cyclone. https://im3.ezgif.com/tmp/ezgif-3-952a57431d.gif

    • Darin

      “Major hurricane” is cat3+ but the forecast discussion says nothing about major hurricane. It even says drier air in future. Are you referring to a different system?

      http://www.nhc.noaa.gov/text/refresh/MIATCDEP5+shtml/171452.shtml

      • Great Winter of 2017 (SMC)

        thats from 6 hours ago and this just happened since then and I saw a hurricane expert on twitter mention this

        • Jason Jackson Willamette

          Here’s the wind forecast for Otis from the NHC.

          ORECAST POSITIONS AND MAX WINDS

          INIT 17/2100Z 17.0N 127.3W 90 KT 105 MPH
          12H 18/0600Z 17.7N 127.4W 110 KT 125 MPH
          24H 18/1800Z 18.6N 127.6W 90 KT 105 MPH
          36H 19/0600Z 19.0N 128.0W 70 KT 80 MPH
          48H 19/1800Z 18.8N 128.6W 50 KT 60 MPH
          72H 20/1800Z 17.7N 130.7W 35 KT 40 MPH
          96H 21/1800Z 16.4N 133.7W 30 KT 35 MPH…POST-TROP/REMNT LOW
          120H 22/1800Z 15.0N 136.5W 25 KT 30 MPH…POST-TROP/REMNT LOW

          • Jason Jackson Willamette

            Here’s the real worry for interests who were already slammed by Irma…

            KEY MESSAGES:

            1. Maria has strengthened to a hurricane and could be near major hurricane intensity when it affects portions of the Leeward Islands over the next few days, bringing dangerous wind, storm surge and rainfall hazards. Hurricane and tropical storm warnings have been
            issued for portions of the Leeward Islands, and these warnings will likely be extended northward and westward tonight or on Monday.

            2. Maria is likely to affect the British and U.S. Virgin Islands and Puerto Rico by midweek as a dangerous major hurricane. Hurricane watches have been issued for the U.S. and British Virgin Islands and
            could be extended to Puerto Rico tonight or early Monday. Interests in these areas should monitor the progress of Maria and follow any advice given by local officials.

            FORECAST POSITIONS AND MAX WINDS

            INIT 17/2100Z 13.8N 57.5W 65 KT 75 MPH
            12H 18/0600Z 14.3N 59.0W 75 KT 85 MPH
            24H 18/1800Z 15.1N 60.5W 85 KT 100 MPH
            36H 19/0600Z 15.8N 61.8W 95 KT 110 MPH
            48H 19/1800Z 16.5N 63.1W 105 KT 120 MPH
            72H 20/1800Z 17.8N 65.8W 110 KT 125 MPH
            96H 21/1800Z 19.0N 68.5W 110 KT 125 MPH
            120H 22/1800Z 21.0N 71.0W 105 KT 120 MPH

  • Rainmaker (San Jose)

    I really hope this one doesn’t become a major hurricane, poor timing for this name.
    https://uploads.disquscdn.com/images/e98e544c601819e68caaa33c17f22d5b269f0755f85ce4484b6f84473f5f7e45.png

  • I was looking at JAMSTEC September seasonals last Friday to see how their precip forecast for DJF shaped up. Since 2013-14 it has done very poorly as almost all if not all other global models had inaccurate forecasts, as well. Hopefully it will cough up another hairball for 2017-18.

  • Tuolumne

    I was struck this afternoon by the autumn lighting on the kitchen window. It’s a combination of the angle of the sun at a given time of the day and the color palette of the season. We now have the same lighting that we get at the end of March, but the environmental colors are different.

    Part of the color palette difference is the plants and part is the atmosphere. Today is smoky, and even if it weren’t we haven’t yet gotten the nice clear air we often get in the cooler months.

    The seasons are changing, and this change is going to accelerate in the
    coming weeks. Ironically, the daily rate of change of solar lighting
    and heat input is going to start going down again once we’re past the
    equinox. But thanks to lag effects, changes in weather and the behavior
    of living things are going to really accelerate for quite a while.

    Here in the zone of marine influence, there’s a big difference between the atmospheric clarity and resulting colors on the landscape during the seasons of the marine layer vs. the winter months. From mid-spring through mid-fall, even when the visible marine layer is missing, there’s usually still a temperature inversion with a certain amount of haziness in the lower layer of air. Even a clear day really isn’t so clear. Once that’s gone for the season, we often get amazingly clear air that lets the low sun angle bring stunning lighting, contrast, details, and colors to the landscape, especially early or late in the day.

    • matthew

      I know that it is autumn when the birds start braining themselves on my windows.

      • Great Winter of 2017 (SMC)

        I know its autumn when it starts to actually rain again

        • Tuolumne

          That’s another milestone and a much more obvious one. This time of the year I always look forward to the first decent cold front of the fall sweeping through the area, dropping some rain to wash everything off, and leaving clear brisk autumn air behind. But after enough years I’ve also learned to look for more subtle changes in the environment such as the lighting I mentioned.

          • Dan weather maniac (ORINDA)

            Yep that’s where I am …. waiting for the first fall front with some rain.

            49 today for the orinda low today, with morning clouds/fog. 75 and breezy now, super nice! Very fall like! Very nice!

          • Tuolumne

            We were at the Lafayette Art and Wine Festival today. The weather was very reasonable – such a contrast to a couple of weeks ago! They even had signs up listing symptoms of heat illnesses and what to do if you have heat exhaustion or heat stroke, plus a church group was giving out free water bottles. I doubt anybody there had heat illnesses today, but I can see why they were prepared…

    • Jason Jackson Willamette

      That first sentence I had to read twice. At first glance, I thought you got struck by lightning through your kitchen window…. : ^ /

      TG that wasn’t the case, wouldn’t want to lose you Tuolumne!

      • Tuolumne

        LoL! Glad to still be around, though I have had a few close calls with lightning over the years.

    • The smell of sage works for me as well. Thanks for writing. You put a lot of puzzle pieces together for me.

      • Tuolumne

        You’re welcome!

  • mattzweck

    here in the high desert Lancaster not much weather still getting. 90 temps. but cooler at night. but today got smokey. been trying to help my gf out with stuff lately. so i’ll try to keep everyone up to date weather here.

    • Amy Cohen

      Send me some of that 90F and I’ll send you some of my 60F. We’ll both be comfy around 75F. Tell your GF you’re negotiating a deal with a strange woman on the internet, it’ll add a bit of spice to your relationship.

  • molbiol

    “Radical greens”; I was hoping this was some sort of superfood I could add to my diet. Oh well

    http://www.foxnews.com/opinion/2017/09/16/dont-blame-climate-change-hurricanes-have-always-been-and-will-always-be-with-us.html

    • happ [Los Angeles]

      FNF = Fox News Fools

      • Thirstier Nick (Santa Maria)

        Fox News = (In best Stephen Colbert imitating Donald voice) Fake news.

        • jstrahl

          Thats spelled Faux News.

    • Jason Jackson Willamette

      At one time, RN meant Registered Nurse. Now it means, Radical Denialists….

    • Darin

      That individual actually received money to write this tripe. Even when he’s making his point that there is climate change through the eons, he uses quotes on “real”.

      “My geology, ecology and natural resources background taught me that climate change has been “real” throughout our planet’s history, including long before humans walked the Earth.”

      Every single one of these paragraphs has a blaring omission of fact or context or framing. I think the most painful thing about the whole thing is the autoplay video from Fox. That’s real unlike the unreal logical pretzel this guy twists to justify his point of view. Thank goodness Chrome is killing that in an October update.

      • Charlie B

        The author has a batchelors degree in geology and a law degree. (Assuming I have the right guy.)

    • CHeden

      It’s the lynch-mob in the comments section that you got be more worried about.

      • molbiol

        Just read thru a couple of pages of comments. Very entertaining.

        • AntiochWx

          More like strained retinas. I’d almost rather stick a cactus in my eyeball.

  • Thunder98
    • Thirstier Nick (Santa Maria)

      Meanwhile, upper 80s could be in our forecast as soon as next Sunday. Depending on where the winds blow.

      • Dan the Weatherman

        When desert cities such as Phoenix begin to cool down as we head into fall, that means that Santa Ana season is around the corner. It takes a cooler air mass over the desert in order for surface high pressure to build over that area, and the jet stream dropping south in the early fall allows that change to occur. During the summer months, a thermal trough (heat low) forms over the area with high pressure in the upper levels of the atmosphere.

    • annette johnson

      We have actually been a few degrees cooler here on the Colorado River. After 110’s just last week, the 90’s feel wonderful. Mornings and evenings have been beautiful. I’m really glad and so is the dog!

  • Charlie B

    7 feet of snow is predicted at the 12,000 foot level of Mt. Rainier this week. 71/2 feet actually, but who is counting. There is a place on Rainier called Camp Muir. It is at 10k feet on the snowy south side. I wonder how much snow that place gets. Paradise, which is about 4 miles away (and 4500′ lower) gets 50+ feet a year.

  • Cap’n

    Chance for a McFlurry in Truckee Wednesday night. Meaningless but exciting nonetheless. Any excuse to put on my mittens in between heat waves.

    https://uploads.disquscdn.com/images/b14a91527f03234fa1a4293875a7e4122bc3d13a6f0ca4e26a8276b5e916f6ee.png

  • Rainmaker (San Jose)

    7:20 and 69 degrees out, god bless Fall

    • Admode (Susanville)

      Amen. 56 degrees here currently. Certainly bears the 115 in Fresno 2 weeks ago.

  • Admode (Susanville)

    On a side note, I realized today that this is the first time in years (if ever during our short time here) that I’ve been able to keep the grass green all summer long. It’s the little things you guys!

  • Bombillo1

    Hey, this thing is going to barrel into us! We’re only about 60 mi from Oregon, yes…

    http://www.goes.noaa.gov/dml/west/nhem/weus/rb.html

  • Bombillo1

    We have made first contact. Shy and wearing little that we would call “clothing”, they call themselves “Rain”. Hoping to meet the entire village, this must be done slowly and with patience however.

  • alanstorm
    • Guitar_grrrl

      Yep, looks like our place here in the S’Cruz mountains. 0.03″ in the rain gauge (drizzle).

      • alanstorm

        That’s at least enough to wash the dust off the cars.

    • Bombillo1

      How lucky that you were able to capture that eagle in this photo.

      • BRP (Ventura)

        That Eagle is about to be killed by Alanstorm’s cat! LOL.. You know Ben Franklin wanted the Turkey as our National Symbol vice the Eagle, due to their intelligence….

        • alanstorm

          Eagle has suffered the indignanty of being a scratching post

  • CHeden

    Cloudy and cool this morning in Cottonwood.
    Gosh, it’s been almost 16 hrs since I last saw the sun….seems like forever.

    • You must be reliving the eclipse or something. LOL

      • CHeden

        Ya, it’s unavoidable.

  • This is a recap of last winter by Judah Cohen. Many of you know he bases forecasts on Siberian snow cover in October and a possible teleconnection to east of Rockies winters. I think it’s a good read.
    http://www.aer.com/winter2017

    • CHeden

      Definitely.
      Needed three cups of coffee to get through it (the first time). Lots of info to digest.

    • Thunderstorm

      AWESOME READ. Will really read it again tonight.

  • Thunder98

    Is the Monsoon season basically over now?

    • CHeden

      Perhaps not purely monsoonal, but the GFS is suggesting a CoL (maybe two) that each may pull in some tropical moisture from the ESE over SoCal about 10 and 14 days out.
      So, don’t give up hope yet!

      • Thunder98

        I’m ready for those cold frontal stratiform rain soon!

        • Hollow Scene (Riverside)

          Or some cold core thunderstorms!

  • rob b-Truckee/East Bay

    For those of you that are #s/analytics fans I suggest BAs latest update on Opensnow, lots to take in for sure.

    https://opensnow.com/dailysnow/tahoe/post/8710?comments=true#disqus_thread

    • AlTahoe

      Yeah that post was awesome.

  • CHeden

    Looks like an interesting pattern may be taking shape over most of the US if you believe the GFS.
    ATTM, most of N.A. is under generally cyclonic or zonal flow at 500mb, with a core low pressure off the Pac NW coast that’s pushing a CF eastward that’s now clipping far NorCal, while us here in the rest of California are under a cool WNW flow regime. Over the course of the next few days, the low will slowly migrate east into the Great Basin, with a new low moving down it’s backside off the NW coast. This second low will then pivot underneath the Great Basin low, and together will carve out a deep NE-SW aligned trough that will dig over much of California to offshore Mexico…and it’s within this general troughiness that several additional CoL’s will be forming over the following week or so.
    As the trough pinches off, a CoL emerges over SoCal before lifting out to the NE as a new trough pushes in from the NW to act as a “kicker”. This first CoL will be somewhat moisture starved, but some convection can’t be ruled out…especially in SoCal depending on exactly the CoL takes up residence before ejecting.
    Then, the aforementioned new PW trough moves in behind the departing SoCal CoL, and in the process, creates a new CoL..this time near San Francisco. This new low looks like it may entrain more moisture than the previous SoCal low, and a broader area of precip and possible instability will impact Cent/NorCal through the extended.
    Will wait for more consistency in the model(s) before going to the hassle of posting a lot of graphics….but at least we’ll have something to follow for the next few days.

    • FolsomPrisonBlues

      Its supposed to be nice and cool over the next week, though WU shows another spurt of 90’s showing up for the Folsom area mid next week.

      • CHeden

        It’s possible/probable there will be some decent katabatic warming as the NE winds associated with the first trough’s passage kicks in. But it should be a transient event….all depends on the finicky behavior of CoL’s in Fall.
        Regardless, after the brief warm spell is when the more impactful CoL sets up. When exactly that occurs, we’ll just have to watch & wait.

        • Hollow Scene (Riverside)

          It will be very interesting if it verifies. I feel like the last half of September to the first half of October usually is a dead spot for SoCal precipitation.

          • Dan the Weatherman

            The second half of September into early to mid October is a transition period for Socal from “summer mode” into “fall mode”. The monsoon activity usually ends about mid September, and the first fall storm system usually approaches the area in early-mid October, sometimes producing rain here and sometimes not, depending on the track. This is often followed by the first Santa Ana of the season. Remnants of tropical systems can still affect Socal in late September, especially during El Nino years and cutoff lows can happen anytime during this period.

      • rob b-Truckee/East Bay

        BA’s latest update he noted a warm up trend but long range models were showing the middle of Oct should cool down again…pretty much on target with a normal fall. Usually Nor Cal sees that one last burst of warmth before the seasons change.

        • CHeden

          The CoL’s I am writing about just showed up on the GFS in the last two runs…therefore this possible shift in thinking isn’t considered credible (ATTM).
          Probably a smart move.

          • Dan the Weatherman

            It is a pattern that could eventually happen, but may not be exactly when the GFS hinted at it in the first place. In other words, it could be delayed until the following week. We’ll just have to wait and see what future runs show and whether some consistency begins to show up in the models.

    • CHeden

      Note, the latest GFS has removed the CoL’s I was writing about.
      Not unexpected. Let’s see if the GFS does another flip-flop (like it sometimes does)….otherwise it’s basically a dry forecast for the foreseeable future.

    • Rainmaker (San Jose)

      no insane heatwave 8-9 days? whew. A lot of folks were talking about something hot during the last week of september

    • Are CoL’s common this time of year? I think you have alluded that they are not a rare event.

      • CHeden

        CoL’s are more numerous in both Spring and Fall when dips/undulations in the wind patterns are most amplified…and thus prone to cutting off.

    • alanstorm

      Here’s the fire-season dousing gift the aforementioned new new PW trough brings, mostly Tues-Wed.
      2.0″ near the Oregon border should do the trick
      https://uploads.disquscdn.com/images/c266c2cbb53f63cf3e7c8adb7c4b3d6cbdad7b49d3b9ba85962bcbaae6ee95fa.png

      • Pfirman

        So CF must mean cold front, but what is PW in this context. I don’t think it means precipitable water.

        I am sure missing a sticky post that defines all the damn anagrams….(.DA).

  • Jason Jackson Willamette

    My dear brother, who lives on St. Thomas, USVI, who survived Hurricane Irma on 9/6, and miraculously, didn’t have any major damage to his house (his boat is gone though) is now about to experience another major hurricane tomorrow and Weds. Maria. One silver lining in the damage Irma did was knock down most of the mature trees on the island, and basically strip the foliage from all the trees. So hopefully, nothing will fall on his house.

    There is a video link on this page of a fly over showing some of the damaged areas … http://viconsortium.com/featured/watch-an-aerial-view-of-hurricane-irmas-devastation-on-st-thomas/

    And then there is rapidly intensifying Maria, headed that way. Your prayers are requested –

    https://uploads.disquscdn.com/images/8361f2b779253bd01620dfd5a650883465f568d5c0b138f0ae190417c7a4384e.png

    • annette johnson

      Thanks for sharing the video. The destruction is far beyond what I imagined. Huge steel beams were even bent. Glad your brother is ok, prayer request heard.
      Talk about adding insult to injury with Maria looming. I suppose those rebuilding will wait until she passes before getting back to work. Keep us posted.

      • Pfirman

        Indeed. How does one even begin to deal with all the trash, which will become airborne again with this next storm. Gut and heart wrenching experience and video.

    • jstrahl

      Best wishes to him and loved ones and everyone in the islands.

    • Sokafriend

      Where are people sheltering?

  • rob b-Truckee/East Bay

    I believe the Reno area was under a fire weather watch this AM-looks like there’s a couple of fires burning in the greater Reno area now. Charlie you seeing any of the action?

    http://www.kolotv.com/content/misc/Brush-fire-burning-south-of-Boomtown-445440413.html

    • Jim (Watsonville)

      Looks like the one near Boomtown is the “Cone Fire”

      http://alerttahoe.seismo.unr.edu/firecams.html

    • rob b-Truckee/East Bay

      The Alert Tahoe network looks like to be picking up both fires
      http://alerttahoe.seismo.unr.edu/firecams.html

    • Charlie B

      I am in South Reno. Just went outside and I couldn’t see or smell anything. That is, I couldn’t see or smell smoke. I did walk through the cloud of someone who was vaping and almost gagged….

      • rob b-Truckee/East Bay

        Millennials now taking over South Reno too?

        looks like the one the fire they’re worried about is behind 4th street, kind of behind the warehouse area in West Reno.
        2nd fire is in timber, across from Verdi near the boarder.

        • Charlie B

          They just ordered evacuations on Woodchuck Drive in West Reno. Very hilly area with lots of fuel (and rattlesnakes.) This area burns every few years. In 2011 (November of a very dry year) a fire started about a mile away from this one and ended up taking out 50 houses including some in my present neighborhood. I wasn’t living there at the time. (We live on a creek that is very densely vegetated and we installed big rainbirds to wet everything in the back but will be useless if/when water pressure is lost….)
          And yes, vaping is everywhere. Did you know that the batteries in those things can literally explode? I have a case where a guy had one in his back pocket and the thing went off like a roman candle. It was caught on a casino surveillance video. He is just walking along and “BOOM!” the thing goes off and blew his pants clean off. He wasn’t hurt seriously, but the video would make me and him a youtube star if I had the guts to post it…(I would probably get in trouble if I did, so I won’t.

          • Hate to break it to you but that was likely an 18650 cell blowing. They are ubiquitous, laptops, Tesla Roadster has 6k of em, flashlights, etc. The key is to use protected batteries or protected devices that keep the batteries from being abused – there are vapers that use what I think are called mechanical mods which are just straight battery-to-heating-element, and the amateur electrical engineer in me says that is likely what made this happen. Those hoverboard fires had a similar origin, 18650 cells, mostly from really shoddy construction and corners cut during manufacture.
            Is this relevant on a weather blog? You bet…while keeping flames from the environment and a direct forest fire, I’ll bet a paycheck that if one of these cells going off hasn’t already caused a wildfire, it will soon – someone leaving a vape fully charged on a cars dashboard in the sun = possibly 30k acres of forest on fire.

          • Charlie B

            Yup. They are manufactured in China. I also heard that they can go off when they are in contact with other metal objects, such as coins. Life used to be uncomplicated.

          • matthew

            Ok, so stick with the good old fashioned bong and bic lighter. Got it.

          • Amy Cohen

            That’s the same area where I witnessed spontaneous combustion starting a fire over a decade ago. I’m sure my 911 call is recorded somewhere. I was frantically running up and down the trail trying to get a decent cell connection. I think I’m still using the same phone, how scary is that!

            2011, I had a friend living in the Ridgeview/Alpine Creek area and I remember seeing the devastation. It’s extremely heart-breaking seeing homes burned down.

            And yes, there are many rattlesnakes in the area. I had a Redbone Hound that was bitten, but that’s a story for another time. I was a complete emotional spaz and had no idea how to handle the situation. Running down the trail carrying my dog, tripping, falling down, crying, … Vet saved her. One year before she passed, she saved me from a Mt. Lion attack in the Galena area.

          • Pfirman

            Dang. I think you have a couple stories for another time, at the very least.

          • Tuolumne

            I prefer to vape natural water vapor outdoors during and after a rain by taking a few deep breaths. Costs nothing and no bad health effects.

  • Great Winter of 2017 (SMC)

    NHC is underestimating Maria, it should have been Cat 4 in last advisory and frankly it could be a Cat 5 based on satellite imagery. Prayers go out Jason’s brother who might take Maria at its peak intensity https://uploads.disquscdn.com/images/7ca780a04de4ffe3f8b377dc1caf49bad322b733506aec0aa64e13a393d0a628.jpg https://uploads.disquscdn.com/images/c454d0c50de728d2aff742229870e5b0c0649cc077cbb77672ad990a596e7075.jpg

  • Hollow Scene (Riverside)

    Ok this question may have no real answer, or speculative at best. Does anyone think this hurricane season could represent a change in teleconnections that could affect our winter? Or are there no real correlations between the two?

    • 82/83 El Nino baby (San Jose)

      I wondered the same. If a hurricane is the WPAC can completely change how the wave train breaks downwind, I would think the strongest low pressure systems on earth, even when in the Atlantic, would have a global effect. Now we wait for the experts to weigh in.

      • Hollow Scene (Riverside)

        I also couldn’t help but notice the Atlantic hurricane drought somewhat paralleled our CA drought. I think the last major hurricane to make landfall was Wilma in 2005.

        • jstrahl

          And we know how 2005-6 turned out in California!

          • Cap’n

            Was that a good year?

          • jstrahl

            Quite good, about 175% of normal rainfall in central Berkeley, heavy rain into mid April.

    • jstrahl

      Both are aspects of changes which are global in nature.

  • Nate
  • Thirstier Nick (Santa Maria)

    Winds have cranked up the last few hours and so are the dew points.

  • Windy, cool and cloudy. No complaints here.

  • Chris

    Maria at Cat 5! 160 mph gust to 200.
    Eek!

    • Jim (Watsonville)

      Really feel for those folks in the path…

    • Oh gawd!

    • RandomTreeInSB

      My god, it’s 2005 all over again.

      • SacWx

        Interesting you mention that – I believe the CA ski resorts got pretty good snow in the winter of 2005-2006, and it also came after a pretty good year in 2004-2005. I heard about this “active Atlantic” analog on another site but not sure it has much meteorological basis.

    • SacWx

      My father lives in Naples, FL and he took the eye of Irma as it came ashore. Fortunately it weakened as it made landfall and his property was spared. Bad news is he just got power and some streets have been flooded with raw sewage and debris due to the treatment pumps being inoperable without electricity. Some parts of the keys from what I understand will have to completely rebuild. I’m not sure that part of FL could take another storm this year (and that’s also clearly true for SE Texas).

      • Chris

        My cousins just bought a house in Miami along with a 4 month old daughter.
        They “evacuated” to Naples to be with his inlaws….. just to find himself taking the dogs out for a pee between eye walls!

      • jstrahl

        My brother’s widow lives in the Orlando suburbs, right by her mom, and five siblings. She’s been there since Jan ’99, the rest have been there since the mid ’70s, they’ve never seen anything like Irma.

  • Thunder98

    Feels like Spirng with the winds. Is a dry cold front coming?

    • Pfirman

      I believe the term Cheden used was ‘moisture starved’.

  • Cap’n

    Castle Peak hidden above 80 this afternoon. Enjoying the cool temps in between heat waves. I’ve been burning wood as my only source of heat 9 of the last 11 winters and I can say that if the temperature forecast holds the next week I will far surpass anything I’ve ever had to burn in September. That probably means nothing but it’s an observation. Luckily the cord maiden gave thorough TLC to the wood these past few months.

    https://uploads.disquscdn.com/images/88f452cd40b9fb2273e5ea80f265e716088960ce068f0d0904e5c6c62a5ecd5c.jpg

    • Pfirman

      Hoping you are no longer ‘between heat waves’ and suspect you are not. On the other hand, you have the glove, scratch that, you would burn less wood with one last hurrah heat shot.

      • Cap’n

        I think all of us are just between heat waves when it’s not actually hot.

        • Pfirman

          Down here we call that night time, or at least we used to.

    • matthew

      I wore long pants today for the first time since May. I am not ready for winter yet.

      • Cap’n

        I am, but don’t fret, looks like 70s again next week.

  • DelMarSD

    After lots of deliberation, I’ve decide to move to Virginia Beach, Virginia. I’ve decided this for a couple of reasons, and have been planning this for a while. Of course, weather was taken into account. San Diego is great, but the weather is pretty boring. I want excitement! The beach is awesome in Del Mar, but I will have beachfront property in VA. I miss the continental climate (though southern VA is much more mild than locations further north along the eastern seaboard). The humid summer nights. The wild spring thunderstorms. Of course, weather isn’t the only reason I’m moving (political reasons, a great job opening, cheaper, wife’s family is in the area, etc.) I just want to say how great all of you have been, and what a great experience it was for me to contribute and be part of this great weather blog. I’ve learned so much. This is truly a wonderful group of individuals. Any suggestions of weather blogs in the area? It seems I’ll have a lot of choices, as there seems to be a bias towards the east coast on many weather-focused sites. While my physical location will change, my fascination with weather and climate never will. I will probably check back here occasionally, and will still definitely display an interest in So Cal weather. And of course I hope (and believe) CA gets a huge amount of rain and snow this winter!

    • Tuolumne

      Best of luck, and enjoy all the rain, convection, and lightning!

      • DelMarSD

        Thanks.

    • Cap’n

      Happy trails and keep in touch! An occasional picture and/or update would be great. Good luck to you.

    • Great Winter of 2017 (SMC)

      Wow your gonna get some wild weather there and also have fun and enjoy the cheaper cost of living! When are you moving? And a little sad to mention that we’ve had several WW people move this year. Good luck to you

    • Wolfpack

      Congrats and best of luck. I grew up in Thousand Oaks and made the move to Raleigh almost 10 years ago. I follow this blog daily because California will always be home. Safe travels and a smooth transition. It’s definitely a change of pace compared to the California lifestyle and the weather never disappoints.

    • SacWx

      I used to live in DC and I really like americanwx.com for east coast weather. A ton of knowledgeable mets on that site and most of the east coast regional forums are quite active. I actually still read through the forum for Hurricanes and major east coast snowstorms. Has nothing on west coast weather though.

      I really enjoyed living in the DC area and found the weather to be pretty dynamic year round. I also preferred the culture out there to most of California. However, what CA lacks in those areas it more than makes up for in natural scenery/interesting micro-climates so I’ve learned to appreciate both places.

    • Dan weather maniac (ORINDA)

      Best of luck to you! I was just in NYC last week and can relate to the warm muggy nights!

    • jstrahl

      Best of luck, enjoy the coastal Virginia weather.

    • Thunderstorm

      Talking the tropics from Mike Buresh meteorologist out of Jacksonville Florida. At times what he says might effect you in Virginia. Has a blog site up most days. Not just good at his job probably one of the best.

    • Jim Yerkes

      Reference weather blogs in the area Dave Tollers of WxRisk. He is on Facebook is out of Richmond VA. Just go to FB and type in WxRisk. He has quite a following. I have been in Noral for 3 years but have followed him several years before when I lived in St. Louis Mo. Being from Philly I,always check on his FB page during east coast snowstorms and of course hurricanes. He knows his stuff but judging by some of his FB postings can be arrogant at times. Hope this helps. JY

    • Darin

      I’m a California native and I lived in VB. I never really knew the difference between Autumn and Fall till then. There’s at least four seasons there. 😉 If snow is forecasted, the whole place shuts down. It is a military town and it’s the South and it still has a very rural feel. Brace yourself because it is nothing like San Diego (been there, done that). The last – and by far most important thing – is the beach is to the east. It sounds silly but if you’re getting on the *64 and your brain is not engaged, you’ll become very familiar with Newton road (which is the opposite way from the beach).

      It wasn’t my style but it definitely has charm. Don’t be a stranger to WW.

    • Bombillo1

      Well this is a shock. Naturally we are going to miss you. Where are we going to get those great North County reports now? I have an interest in an avocado tree in La Jolla, how am I to know of its hydro-logical state? The photos, the water temps in my favorite California ocean setting? I have deliberated on this move for about 15 minutes now and have decided that it is not a good idea. Please re-consider.

    • Grew up in this part of VA…attended Old Dominion then moved out west after college. Loved living with 4 distinct seasons though never fond of the summers. Best wishes to you. Love the drive up to Williamsburg at this time of year–how nice!

    • weathergeek100

      Oh no! How sad. You’re the north county reporter for WW! I grew up in north county (Vista specifically) so I was always looking forward your postings! As many here know- San Diego is unique. Winter is the driest along the CA coast….until a crazy cutoff low hits when I really enjoy getting those reports of once-in-a-blue moon phenomenal rainfall totals! Summer is the warmest and muggiest along the coast due to close proximity to the monsoon and far proximity from the cold CA current. I loved reading your reports when dewpoints hit 70 and water temps reach the mid 70s, and when that rare summer thunderstorm hits!

      Enjoy VA beach. Definitely more interesting than San Diego. Weather is a big part of peoples lives back east because unlike us, it affects them on a daily basis. Unless there’s a drought, there won’t be a dull moment in VA! Thunderstorms, nor’easters, you name it! Unlike us though, no unique microclimates really. Probably 5 degree difference (maybe more sometimes) between coastal and inland temps and that’s over long distances. Enjoy and we’ll miss you. Don’t be a stranger! Report back!

    • Nathan

      Good luck!

    • Sokafriend

      Be happy!

    • 805 Weather (Camarillo)

      Ahhh man. I wish you the best out there!

  • Cap’n

    Radar looks great over Washington and moving into Oregon, a nice proper fall system. Should this about take of the fires up there, assuming it is widespread enough?

  • RandomTreeInSB

    Eye of Category 5 Hurricane Maria now right over Dominica, population 73 thousand… https://uploads.disquscdn.com/images/f816abc22310ab7528b0f1e00da6abc6f25740cb369275c37f4d91b613c03acc.gif

    • Dan the Weatherman

      I didn’t realize that it strengthened to a Cat 5 already! I just verified that it was a Cat 5 from visiting NHC’s website. Boy that thing intensified rapidly!

      • Tuolumne

        Happened today.

        • Dan the Weatherman

          I heard earlier today that it was a Cat 4.

      • Bombillo1

        Dominica’s lucky day…

      • Great Winter of 2017 (SMC)

        Winds likely dropped to 140 MPH after going over 5 k mountains according to someone with good TC info and knowledge on twitter

  • tomocean

    Wow! What a great weather day. I had a day off and climbed a peak near Ebbets Pass.
    Lots of beautiful cloud cover on the way this morning. You could see the line where the front was. https://uploads.disquscdn.com/images/2e1a01222d378c5645b55c49244fbcc8ddaa5fd94b6194c2d3c6dc662033b129.jpg
    The wind up high around 10k feet was insane. Forecast was for hurricane force over the ridges and having been through a few, I can attest that they were. https://uploads.disquscdn.com/images/bacb9a9ed22877f17752cf9de217017c945e5046749f72689127ec0a1dfa646e.jpg
    The weather turned even more dramatic on the way home. https://uploads.disquscdn.com/images/b819f0702d133f5173d5399ecc68d69af0a8b612f383e28220ce99339156a4bc.jpg
    To cap it off, there was a dusting of snow at Sierra at Tahoe! https://uploads.disquscdn.com/images/f49449132c2721fcb42b08b4e8410f55479694b4c2b667eebc3e227c8299870f.jpg

    • Dan weather maniac (ORINDA)

      Love to Mother Nature!

    • Guitar_grrrl

      Gorgeous photos!

    • Jason Jackson Willamette

      Only on this blog to we get treated to such great stories from, and about, nature.

  • Fairweathercactus

    The frost season is coming in fast. First time since mid July Big Bear hit 32 for a low.

    • Dan the Weatherman

      It is certainly beginning to feel like an early October pattern here in Socal.

  • Eddie Garcia
    • Unbiased Observer

      I’m backpacking this weekend around Lake Edison (Fresno County), could be interesting!

      • Tuolumne

        That reminds me of a story from nearby Florence Lake. Back during the 1975-77 drought the lake was way down. Backpackers were parking near the lowered lake surface then catching the boat to the end of the lake to save a few miles of hiking.

        Well, there was an unusual summer front (not sure if this was ’76 or ’77) and the lake level came up 10 or 20 feet afterwards. The person I talked to had ridden in a boat over submerged cars caught in the rising waters. Bummer for folks coming back from their backpacking trips!

        • 805 Weather (Camarillo)

          They still down there lol?

          • Tuolumne

            Probably removed during a subsequent drought, but who knows?

      • Nathan

        should be beautiful

  • Alice Paul (LA)

    Perhaps I’m the only one awake in LA to report a small 3.6 earthquake. It was just off the 405, south of Getty Center Drive.

    • Dan the Weatherman

      I didn’t feel it here in Orange, as I am too far away to feel a 3.6 from West L.A.

  • 805 Weather (Camarillo)
    • CHeden

      A thing of beauty.

  • inclinejj

    Didn’t get a chance to mention this yesterday. Heavy drizzle, enough to get the streets wet and use wiper blades. The drizzle was actually much heavier in South San Francisco than Pacifica. Didn’t clear up until Almost 3:30. When I took my dog out for a walk at 6 it was cool and the air had the smell of rain.

  • Thunder98

    I can see my breath this morning

  • CHeden

    51F calm and mostly clear this morning in Cottonwood. ANNND, beginning last night I can see Shasta again! At long last, a new airmass is finally in place and we can breathe easier.

  • Cap’n
  • TheNothing

    Puerto Rico is going to take a direct hit from a Cat 5 hurricane tomorrow, I can only imagine the aftermath left in Maria’s wake.

  • CHeden

    Commensurate with our air mass changeover, we need to look what’s out in the Pacific to understand the causation of the emerging western troughiness.
    1st image is the current 500mb setup. What we see is a dominant high pressure dome out ~-150W, with a low spinning underneath in a developing Rex Block position. On the NW flank of the high, a closed low is anchored south of the tip of the Aleutians, with a developing trough/LP now digging over much of western NA…i.e. a developing Omega Block. The setup is rather unusual, and in the past I’ve referred to these type of setups as a Hybrid Block…so I’ll stay with that until corrected.
    One of the key characteristics of a block is they tend to hang around for a while, and this one will be with us in one form another for much of the week.
    By Friday (2nd image), the Hybrid Block is relatively unchanged except the HP ridge and adjacent lows are just beginning to “roll over”.
    By Sunday (3rd image), the block is continuing to roll over/flatten but is still intact..with notably the west coast low opening up into a deep trough.
    By next Mon/Tues (4th image), the west coast trough is finally starting to drift SE with all of California coming under a dry NE flow which is when the strongest heat/Santa Ana’s should occur.
    By Wednesday (5th image), HP ridging off the coast remains located over the coast all the way north of BC and the Northwest Territories. By this time, NorCal will be seeing some increasing onshore flow with SoCal still getting NE winds. Of note is the remote possibility of some Pacific energy undercutting the western high should the ridge continue to push even further north…and is certainly something to look for.
    After that, well not much point in going into a lot of detail since as we know the evolution/breakdown of blocks are notorious for defying the pundits and doing whatever they damnwell please….but a lot of possibilities nonetheless to keep us amused (hopefully).
    https://uploads.disquscdn.com/images/1d16d10dcc685663af741d72e887847b62b8036a44766a14f0b576aef6b267d0.gif https://uploads.disquscdn.com/images/410a032e16faf2609b8de5d8e895c7ffeeee646c94d6385ca9e4db3ee5e65912.gif https://uploads.disquscdn.com/images/63e94979d5d3d0b28c77aded1dc8554922f660a017b51dd06cfb24e176ecf41a.gif https://uploads.disquscdn.com/images/0f1fbc165fe8be9f0920d62538658edddd630d8c5ebc24d7394276b840385fc3.gif https://uploads.disquscdn.com/images/31451aa8473f5d6b103d131b6cd20a81f54a067d75b2253d4f073306eb0c56e0.gif

    • 805 Weather (Camarillo)

      I find it extremely interesting this trough is elongating itself very similarly to the way last year’s BC troughs were swinging in. It even elongates it general area in the same way as last year extending from NE to SW… To note this would be that same time of year we started seeing such a thing. A difference from last year was the abundance of extratropical low pressure system that kept digging SE below Hawaii creating a good path way for subtropical moisture to shoot NE towards the elongated trough. Also if this were to be similar to last year (I’m just comparing for fun) we would have to begin seeing those lows forming under Hawaii again creating the NPAC Rex block pattern that was so common last year. Interesting times possibly ahead indeed.

      • CHeden

        Kudos for the additional thoughts.
        Yes, not too much south of Hawaii. And as you astutely mention, a key source of last year’s moisture feed is missing.
        The low to the north, as part of the recurring Rex Block has been pretty consistent, though.
        Lastly, check out how the NPac H.P. elongates NE-SW over the top of the trough in about 2-3 days. Looks like it’s setting up a ENE flow that extends from the High’s eastern flank off our west coast all the way to SE Asia. https://uploads.disquscdn.com/images/0a9480061ff5e8ab1abf6b95f6259d4a0acdf6c6bfac8e895800300453836655.gif

        • 805 Weather (Camarillo)

          I’m going to look into La Niña years & dive into some finer details later today if I get the chance.

  • 805 Weather (Camarillo)

    I understand this may be off topic, but it does give us an idea of what we could have been seeing with the Oroville spillway failure IF it had occurred… This video shouldn’t be passed up, & was filmed in Laos. https://twitter.com/wasilewskitomek/status/909698446252216322

    • TheNothing

      I think I would’ve picked something faster than that Caterpillar Grader to get the hell out of Dodge.

      • rob b-Truckee/East Bay

        I was thinking the same thing, seemed a bit odd he was trying to back it up to get away.

        Surely shows the sheer power of water and how quickly it can rise and overtake everything around it.

      • Hollow Scene (Riverside)

        Maybe he was trying to save the equipment or something, but it still was a little funny

        • TheNothing

          Actually after watching a second time I noticed he jumped out and ran leaving the tractor to block the road preventing the other cars and trucks from leaving.

          • Charlie B

            Obviously, a North Korean political hit job.

      • 805 Weather (Camarillo)

        Thinking the same thing, plus he blocked those two other cars from proceeding. Imagine how quickly your mind is moving in something like that.

      • Nathan

        why on earth would they not immediately go UP?!

  • Thunderstorm

    Good read on – Talking the tropics – this morning. Maria to stay farther west especially if it slows.

  • CHeden

    So, now I that I’ve apparently bored everyone to tears talking about blocks/etc.,
    check out what might happen in about 10 days as a result/part of how this setup evolves in the LR (10 day and beyond).
    A potent easterly wave is forecast to start overrunning Az next Wed./Thurs. spreading westward to SE California by Friday before spreading north over most of the southern half of the state. Not sure if this is a true monsoonal flow, though, as I think the driving energy will come from the blocking flow rather than monsoonal flow. But, either way, juicy air along with good dynamics would overrun SoCal and hang around for better part of a week. Here’s the precip totals starting next Friday then by the following Wednesday…pretty impressive in SoCal for this time of year.
    https://uploads.disquscdn.com/images/b12f2b89d77c502909c7a10305ab3d1668e28e0666929db2eac69b19569ebf0e.gif https://uploads.disquscdn.com/images/f573a7e4b4ab3f2488845526a1e52aa1ab9b8990b49291b67c758b49d42d4f52.gif

    • Fairweathercactus

      Drizzle on the first slide and monsoonal moisture west of the mountains that will never take place on the second. The CA dry hole looks to be back this season.

    • molbiol

      Sorry but the 12Z shows no such scenario and the majority of the 06Z ensembles favor an open trough. The CMC has shown this scenario a couple of times but also has no ensemble support or consistency. The ideal setup would be similar to Oct 18-19 2010 (shown below; 2nd image) where a widespread outbreak hit Socal. For now though I must agree with cactus on this one

      https://uploads.disquscdn.com/images/9c8bb8016b560f1bc81504948defef09cf1b050db7ce95803af4387b1c0bf909.jpg

      https://uploads.disquscdn.com/images/2b85de5cc08159247035e10126e0e31d64bbe981c9091ddb3b046c28140c92eb.jpg

      • CHeden

        Thanks. I just noticed that. Keep in mind though, the GFS also has shown something “similar” in recent runs….but as you said with no consistency, so there is still a lot of uncertainty with 2 of the 3 main models (I don’t know what the EC is showing). IMHO, the whole scenario is hinging on how a huge block(s) evolves…hence the big swings in possible solutions.
        I’m far from making a call for wetness, but at the same token I’m not ready to write it off, either. Will know more once some moisture starts working into Arizona to gauge how far west it will progress.

        • molbiol

          00Z EC does have a CoL in the “sweet spot” off Baja coast by early next week. Not sure its believable though due its bias toward these patterns which more often than not fail to occur

    • Yup. This is good treatment for keratoconjunctivitis :))))

  • 805 Weather (Camarillo)

    Classic east-based Niña developing quickly… https://twitter.com/mjventrice/status/910190528335138816

    • 805 Weather (Camarillo)

      Paul Roundy was noting this morning the similarities in SSTA’s during the onset of the Niña of 09/96. & for comparison he posted some graphics. https://uploads.disquscdn.com/images/90096051568548e057fddd82e26125a7c907af7f17fccb9de7c9d75298b9d350.jpg https://uploads.disquscdn.com/images/8026162f10388d0a996d7709a76bacdda1f241b2a34eb791ce9c616a2893f790.jpg

      • 1996-97 There was a huge A/R that year that flooded Yosemite Valley. Then the tap got shut off. The early wet / late dry Nina thingy.

        • 805 Weather (Camarillo)

          Yep, well documented as well!

          • Dan the Weatherman

            I remember the 1996-97 year well. It was quite wet here in Socal from the end of October until the end of January, then the spigot shut off almost as suddenly as it did in January 2013. As usual an early ending rainy season caused unseasonable heat in the spring, and the spring of 1997 had some very hot weather in March and May.

          • thlnk3r

            Well there are other teleconnections to factor in for this upcoming season. But 96-97 was very dry in Socal. Less than 50% rainfall 🙁

    • Looks like 2015-16 finally gave up. LOL

    • Dan the Weatherman

      No wonder why the Atlantic hurricane season has ramped up late this summer. Developing La Nina years often lead to more favorable conditions for a more active Atlantic season due to reduced westerly wind shear over that region.

      • Thunderstorm

        Yep probably will set record this year. Migratory birds already showing up around the SF bay. Gona get cold early this year!

  • tomocean

    The rabid anti-global warming deniers are all over this story. It looks to me like models were slightly off from reality, but that the trend line is still up and to the right. Maybe that will give us more time to take action. Hahaha! Right.

    http://www.theaustralian.com.au/news/world/the-times/experts-admit-global-warming-predictions-wrong/news-story/fa5d90b23d16eb08e7d0d6b14d1bbf0c

    • The link kept popping into “subscribe mode”.

    • jstrahl

      Three hottest years on record, in descending order:2016, 2015, 2014, the 2nd and 3rd may get displaced down by one notch due to 2017.

      • Charlie B

        My father in law is a rabid Dodger fan. Therefore, his favorite saying is “Wait ’till next year.”

        • jstrahl

          Wow, that goes all the way back to the Brooklyn days. 🙂

          • Charlie B

            It does. We pick him up from the airport this evening after a month in England and will be presenting him with a autographed Kershaw jersey. He has received a lot of gifts and honors over the years but this one will be his most treasured.

          • jstrahl

            Lucky guy!

    • Jeff

      Looks like that link leads to a paywall. Here is another:

      https://www.nature.com/news/limiting-global-warming-to-1-5-c-may-still-be-possible-1.22627

      Looks like you need access to read the original article:

      http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo3031.html?foxtrotcallback=true

      The basic findings seem to be that the IPCC 2013 estimates for the amount of global carbon that would lead to a 1.5C change were off by a factor of 3

      I agree that we really should not be putting too much stock in the precise details that long term computer models predict as most details are likely to be wrong when we look back 10-20 years (too many variables)

      However, that certainly does not change the long term trends

      The fact that the new findings put the Paris goals for 2030 and beyond into a more reachable scenario should allow for more concrete goals and policies to be put into place.

    • My takeaway was the oceans have been sucking up a lot of heat as they always do but not releasing it into the atmosphere. I guess if one could wave a wand and reduce CO2 to under 300ppm overnight and keep it there for 200 years, air temperatures would still be anomalously warm for decades if not longer.

  • Wolfpack

    Mexico City just rocked by a 7.4.

    • Nate

      USGS revised to 7.1. Unfortunately pretty close (~130km) to Mexico City, but looks to be somewhat deep (50km). Regardless, bad situation.

      • Nate

        Wow, just realized that this is the same day as the deadly 1985 quake. Eerie.

        • alanstorm

          Totally bazaar.
          Sept 19, 1985, 8.0
          Sept 19, 2017, 7.1

          The more the ring of fire gets these major quakes, the more the risk goes up for L.A. & S.F.

          • 82/83 El Nino baby (San Jose)

            Is this true? I ask because in the last 20 years, the entire ring of fire has had huge earthquakes (Japan, Chili, New Zealand, Alaska, etc), yet the faults along the continental west coast have been quiet.

          • alanstorm

            For the vulnerable Bay Area, 6.8 in 1868 on the Hayward Fault & 7.8 in 1906 on the San Andreas just south of SF were the last big ones.
            Anything near 7.0 on the Hayward now would be devastation…..
            And look at all the biggies in SoCal in the late 1800’s.
            Besides Landers, they’re WAY overdue

          • Pfirman

            So what was this one? Not big enough?

            https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake

          • alanstorm

            I don’t think so because of the distance & a 6.9 is no 7.8
            If it had occurred in Hayward or South San Francisco, different story.

          • Nate

            Fortunately, no. Earthquakes on the other side of the world do not increase the chances of a CA quake. I wouldn’t exactly argue that the West has been quiet either–since 1997, there have been 12 quakes 6.0+ on or near the west coast. In California, there have been quite a few (Ferndale quakes, Hector Mine, San Simeon, El Mayor-Cupacah, and Napa to name a couple).

    • Many on the immediate coast were feeling warm onshore breeze. I guess the heat ridge said microclimates be damned.

    • Nathan

      In addition to the record heat, did SF/Peninsula also incur record heights as well? That might explain total disappearance of marine influence. The layer was just squished and shunted to the west.

      • inclinejj

        It was 106 plus in Pacifica with a couple local reports at 108. So, Yes!

      • Great Winter of 2017 (SMC)

        108 one day 107 the next here on Friday and Saturday of Labor Day Weekend

    • Pfirman

      I wish I had a dollar for every time that article said ‘Swain said’.

  • 82/83 El Nino baby (San Jose)

    Interesting wave pool action on a river from the Mexico earthquake:

    https://twitter.com/CarlosVinicioAR/status/910218738628157440

    • It’s extremely obvious from the footage coming out of Mexico City that their earthquake early warning system saved quite a few lives today. Some folks actually had time to leave the buildings they were inside of when the sirens sounded and shoot footage of subsequent collapses from a relatively safe spot outside…which is both terrifying and a tremendous success at the same time.

      As it stands, California has no such system, though it’s finally in the works and should be partially implemented next year (and fully implemented in 2-3 years).

      • celo

        It is insane we do not have a system like this yet. Especially for our urban centers. Ridiculous!

      • Nate

        We do have the system, and it does work (I can vouch for it after seeing it in action during a quake at the Berkeley Seismo Lab), but it’s not quite ready for public release yet. Beta users, including public agencies, such as BART, have been using it since 2012.

        • My understanding is that a fairly bare-bones version exists, but there was a desire to have more hardware/instrumentation in place so that warnings could be more specific (arrival time, estimated intensity, and geotargeting) and therefore useful, as well as the logistical issue of how to disseminate the warnings publicly.

          • Nate

            Yes, exactly. Only about 40% of the planned sensors are in place, so there are still some “blind zones” in the state. The warnings are fairly accurate with regards to magnitude and location at the moment, but the actual algorithm (ElarmS) is still being tested. It’s supposed to be rolled out next year, but seeing as there are issues with funding, it could be longer.

        • I’ve listened to BART radio channels and heard them call out warnings and actually used it to get outside. The time between the warning and the minor quake was very small, was an odd experience, I suppose since it was a minor localized event I would have less warning than if it was bigger and further away. Being so close to Hayward and other faults is sometimes unnerving – I don’t listen to their frequencies often…though I might tune in if $hit starts to hit the fan in slow motion, like quake storm of increasing amplitude.

          • EQ early warning won’t help much for a Hayward quake, unfortunately, since its epicenter would be so close to population centers. But for the San Andreas “Big One”–a 7.5+ southeast of Los Angeles, it could provide upward of 50-60 seconds of warning.

    • molbiol

      The biggest hurdle right now is that current cell phone technology does not have the data bandwidth to handle sending out warnings to 35 million people simultaneously. Nevertheless, standard television and radio alerts along with civil defense sirens (similar to the sirens that go off during tornado warnings across the midwest) would be a nice temporary fix until cell phone technology ‘catches up’. Its very frustrating that such a system is just now being implemented in the US.

      • Indeed. See the below video for a case study of the siren approach. The cell phone notification issue is nearly resolved, though, based on extreme prioritization and geotargeting. In other words: If all other traffic gets delayed, and you can limit the notification to people who would most benefit from receiving it, then it’s do-able with today’s technology. The trick will be writing a clever enough algorithm to get that bit right.

        • celo

          It is amazing, In the center of the technological world we do not have in place a system that is connected to our vast seismic network.

        • molbiol

          A more ‘localized’ warning system to people most at risk of experiencing strong shaking would cut down on strain to cell networks especially if ‘surrounding’ traffic is blocked as you said. Creating such a program is the challenge

  • molbiol

    One area that REALLY needs an early warning system is the Pacific Northwest as most people on this blog know:

    http://discovermagazine.com/2012/extreme-earth/01-big-one-earthquake-could-devastate-pacific-northwest

  • Thunderstorm

    Is this correct Fontana just had 4.2 ? Daily Mail.com has video of the Mexico quake shows the city bouncing around.

  • Great Winter of 2017 (SMC)

    Such a MONSTER of a hurricane, 165 MPH sustained winds and gusts to 200! Beautiful and stunning on satellite, but a sad situation for those in PR and USVI
    http://weather.cod.edu/data/goes16/meso2/13/meso2_13_20170919222658.jpg https://uploads.disquscdn.com/images/0fc3c63687fa081338b1bf7a48da93aebc1ceb2e0564243b6055caa141ea7c1d.jpg

  • alanstorm

    Horrifying footage of buildings collapsing after today’s Mexico City quake.
    Hope people got out in time!
    https://mobile.twitter.com/MikeElChingon/status/910261796400898048?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Etweet

  • Nate
    • Nate

      One thing to note here is the period of the shaking–Mexico City’s sediments have a resonance similar to that of mid-sized buildings (~2.5 seconds). I bet we’ll see a similar damage pattern to 1985 with this quake–mid sized (around 15 stories) buildings sustain the most damage, while shorter and taller ones escape unscathed.

    • Nathan

      ….never going inside any buildings in Mexico…

  • Great Winter of 2017 (SMC)
  • Shane Ritter

    Seeing people say this fall is analogous to 96/97, or 05/06 with big hurricane season. Those where great winters here in the Sierra, big snowpack, and floods both years. Even the winter 12-13′ started off amazing. So who knows! Still got the fingers crossed!

    • rob b-Truckee/East Bay

      12-13 did start off with great snow in Dec…but then basically cutoff after that. After that it seemed like Spring came in Feb and we didn’t see any real action after.

    • AlTahoe

      The early start to winter has me concerned. Tahoe is only 7″ below the maximum height currently. The lake has never been this high going into a winter before. Not sure what they are going to do with the water if we have an early wet start. Reno better get the sandbags ready.

      • 805 Weather (Camarillo)

        That’s really interesting, I didn’t know this would be a first on record for the lake to be that high headed into the season…

      • Shane Ritter

        It could be a curse or a blessing. If we have a 14-15′ style winter, we will be thanking the heavens we have that water. If we have any kind of winter over 125% it could be problem. Don’t forget, stampede is still over 200k and Boca over 35k. The entire storage system is still at like 85%. I have never seen it so full. I remember in July of 15′ as a fly fisherman, I would have straight up murdered people for an extra 15k acft in stampede!

        • Cap’n

          I drive over it once a week and have been surprised to see only one gate open when the lake is still so high. It brings to me the next question I have and have always wondered: Does Pyramid have a limit as well? I always picture it as being so big that it’s practically limitless which would make me wonder why they haven’t drained Tahoe a bit more. Over here at Donner the draining has been in full force since Labor Day.

      • SacWx

        Is that at all due to the storms this summer or is it purely due to last years winter?

  • Great Winter of 2017 (SMC)

    Just doesn’t get much more intense than Maria in the Atlantic, 175 MPH sustained winds and latest dropsonde shows surface winds of 193 MPH, truly an incredible Hurricane https://uploads.disquscdn.com/images/20319229d4e8c4d987ad4af592cdba365828e2399e6c67802db1ae759bd4e347.jpg

    • thebigweasel

      It’s going to traverse the length of PR, isn’t it? Those poor people…

      • At the moment the eye is forecast to pass south of San Juan on a SE to NE track. It’s still too close

        • CHeden

          That puts San Juan on the NE quadrant of the eye wall.

      • 805 Weather (Camarillo)

        Yes, & Maria is worse than Irma with intensification still occurring as it hits those warmer waters. This is honestly tough to watch.

        • Great Winter of 2017 (SMC)

          It may approach 190-200 MPH if it keeps RI

          • 805 Weather (Camarillo)

            My latest comment above should put into perspective what they’ll be dealing with.

        • Thirstier Nick (Santa Maria)

          I sure hope it misses the East Coast.

  • 805 Weather (Camarillo)