Major Arctic outbreak across the Western United States; rare Central Valley snowfall possible

Filed in Uncategorized by on December 1, 2013 104 Comments

12/5/2013 Update regarding low elevation snow potential

The ongoing Arctic outbreak across the western United States is still on track to allow for exceptionally low snow levels in California later Friday into Saturday across all of Northern California. Precipitation will begin on the North Coast during the daytime and spread southeastward towards the Bay Area by evening as a weak low pressure area slides down the Pacific Coast. This system, though barely visible on satellite imagery this evening, is currently producing snow along the Washington and Oregon coastlines.

NAM depiction of very cold weekend storm system. (NCEP/NOAA)

NAM depiction of very cold weekend storm system. (NCEP/NOAA)

Snow levels may be near sea level initially on the North Coast, and while accumulations along the immediate coastline are unlikely, flakes could fall on the beaches near Eureka and Arcata. The system will be moving into a very dry continental polar airmass over California when it makes its approach on the Central Valley, and dewpoint depressions will be very steep. This will allow for strong evaporational cooling as the atmospheric column moistens at the onset of precipitation, likely bringing snow or a rain/snow mix all the way down to the Sacramento Valley and San Joaquin valley floors (under 500 feet). Above 500 feet or so in this region, accumulating snowfall is likely overnight Friday into Saturday morning. Accumulating snowfall is also possible on Saturday morning at even lower elevations in the far eastern Sacramento and San Joaquin Valley, where an inch or two could fall down to 200 feet or so. In the Bay Area, conditions will not be quite as favorable as in the Central Valley, but while precipitation will probably start out as rain under 2000 feet snow levels will drop quickly on the back end of the precipitation band associated with the cold front, possibly bringing some snow accumulations down to 1000 feet and a brief rain/snow mix to even lower elevations. In addition, frontal lifting may be strong enough to generate some weak convective activity near the frontal boundary, which could produce an isolated thunderstorm or grapuel/hail down to sea level just about anywhere. There is some uncertainty regarding how long showers will linger behind the front. If any persist into the late afternoon or evening, they will likely fall as snow.

This system has the potential to produce snow in parts of Northern California that very rarely see it. While I certainly don’t expect widespread images of iconic Northern California landmarks buried in the white stuff, many Northern Californians may be in for a pleasant surprise when they wake up on Saturday morning. Stay tuned, and post any photos of unusual snowfall to Weather West’s Facebook page!

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12/3/2013 Update regarding potential for very low snow levels this weekend

A small low pressure system is now expected to develop near the Washington state coastline on Thursday and swing southward down the Pacific coast into Northern California on Friday. This system would be fairly unremarkable, bringing only light to moderate precipitation, if not for the very cold airmass in which it will be situated. The trajectory of this system suggests that there won’t be strong enough southerly winds to scour out the existing cold air, and that the easterly flow on the north side of the system may be able to wrap some even colder air over Oregon into the circulation. While it’s too early to know exactly how this event will unfold, current model solutions suggest that snow levels Friday into Saturday may drop below 1000 feet across much of Northern California. It’s not entirely out of the question that some snow could even fall closer to sea level, especially in the Central Valley. Certainly a system to keep a close watch on over the next few days!

NAM projection for very cold California storm system on Friday. (NCEP)

NAM projection for very cold California storm system on Friday. (NCEP)

 

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Recent weather summary

Unusually dry and stable conditions continued through the end of November across most of California. November precipitation was well below average, especially in the northern part of the state where precipitation was limited to essentially one modest storm event around the middle of the month. Warm conditions are currently being experienced as mild offshore flow and persistent geopotential height ridging allow for a weak storm track across the Eastern Pacific.

compday.9GTvjmuEGMcompday.eWoJcPW9WA

Above: geopotential height anomaly for calendar year 2013 (left) and Nov. 2013 (right) 

I had an extensive discussion on the meteorological characteristics of the current year-long California dry spell in an earlier blog post. A quick check of recent data suggests that the same spatial pattern of anomalously strong geopotential height ridging in the Gulf of Alaska continued through the month of November and will proabably continue for at least a while still. In fact, over the past 30 days the amplitude of the pattern appears to have further increased, with a very high amplitude ridge extending well north over Alaska. This highly-amplified north-south oriented flow pattern will be a major factor in the upcoming Arctic outbreak over the western half of the United States.

 
Dramatic change in the short term: much colder conditions, though little precip

The aforementioned high-amplitude ridging in the Gulf of Alaska and the associated “blocked” flow over the Pacific Ocean has led to an accumulation of very cold air on its downstream side over western Canada. As the entire pattern shifts slightly westward (retrogresses) this week, this modified Arctic airmass will be able to spill southward and even slightly westward over the West Coast and intermountain states.

GFS depiction of high-amplitude flow over the Gulf of Alaska blocking ridge (NCEP)

GFS depiction of high-amplitude flow over the Gulf of Alaska blocking ridge. (NCEP)

The initial push of very cold, modified Arctic air will be associated with a sharp cold frontal boundary that will sweep south from the Seattle area tonight to the San Diego area by Wednesday. This front is rather impressive dynamically but very moisture-starved, so precipitation associated with it will be quite light south of the Oregon border. While scattered showers are possible for a brief time this week in most parts of California, only very light accumulations are expected and some places may see no precipitation at all. Noteworthy, however, will be the rapidly falling snow levels that will be associated with any precipitation that does occur–by Wednesday morning, snow levels should fall to 1500 feet or below in the north and 3000 feet or below in the south. Snow levels will really plummet on Thursday, but all precipitation will have exited the region by then.

NAM depiction of sharp, well-defined cold front entering California from the north. (NCEP)

NAM depiction of sharp, well-defined cold front entering California from the north. (NCEP)

By Thursday, an exceptionally cold airmass will be in place across nearly the entire Western United States. Projected temperature anomalies are very impressive for early December, and could potentially be record-breaking. Sub-freezing daytime highs are possible in Washington and Oregon, including Seattle and Portland. Long-duration hard freezes are expected across a large portion of California, with daytime highs struggling to reach 50 degrees even near the coast. While it’s still a bit early to tell how low overnight minima may go late this week, it’s entirely possible that some colder valley locations near sea level will fall below 20 degrees. Overall, this airmass appears to be as dry as one might expect for a cold continental source region, though it’s possible that very weak disturbances in the flow could being a few snow showers to unusual locations along the West Coast next weekend. In any case, this appears to be a pretty long-duration cold event, as the GFS/ECMWF ensembles keep a very cold and dry pattern entrenched for the next 8-9 days at least.

Is there any hope for rain?

We’ve now entered December, and the rainy season in California should be in full swing. As most of us have become acutely aware by this point, the prevailing pattern has been exceptionally stable and dry. While the impending cold snap represents a large change in the sensible weather, the overall large-scale pattern that’s allowing it to happen is actually not very different from the one that has been so persistent for nearly the past 12 months.

GFS ensemble MJO forecast. Note the eastward propagation of the MJO signal. (NOAA/CPC)

GFS ensemble MJO forecast. Note the eastward propagation of the MJO signal. (NOAA/CPC)

Typically, a blocking ridge as strong as the one projected for this week is eventually undercut by strong westerly flow as the flow pattern becomes increasingly unstable, which either collapses the blocking pattern or allows a low-latitude storm track to develop (which would be favorable for California precipitation). There are early indications that this could occur in 9-12 days as the blocking pattern finally breaks down, though uncertainty regarding this potential evolution is enormous. One argument in favor of California finally seeing some meaningful storm activity by mid-December is increasing activity of the Madden-Julian Oscillation in the West Pacific. This mode of intra-annual tropical atmospheric variability is strongly associated with California rainfall events when its active phase shifts eastward, as is currently being suggested by dynamical model forecasts. For now, we’ll just have to wait and see if this comes to fruition: this persistent ridging has thus far been seemingly impervious to previous attempts to knock it down, so it’s possible the models are being too aggressive with its demise. We’ll know more in a week.

© 2013 WEATHER WEST

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  • …and then there’s the 00z GFS, which throws a rather startlingly cold storm into the mix next weekend. Seems extremely unlikely, but it could be an interesting week. Stay tuned!

    • Avery Smith

      00Z GFS is pretty amazing at the end for NorCal, with a perfect combination of Pacific moisture and bitterly cold continental air…never seen a setup like that…RBL and RDD would get hammered with snow! 100 or so miles south with that track and SMF gets crushed too!

      • If that track panned out exactly as depicted, snow would be possible for the entire Central Valley and probably the Bay Area as well. Clearly, that’s a pretty extreme long shot, since this system didn’t even exist in the last model run. Still…continental polar airmasses can throw some surprises at us, and the 1990 event this is being compared to did in fact bring some light snowfall to sea level in a few CA locations. Certainly worth following this week…

        • Avery Smith

          Yes, very amazing—I didn’t look past the resolution change…you are right…big time long shot, but fun to see how it will play out. In any case, I think some type of overrunning event is likely for the NorCal valleys in 7-9 days.

          • Just for fun, I checked the snow diagnostics for the 00Z GFS. Next weekend looks, ah, pretty interesting in NorCal. The ECMWF is showing another system of similar interest, though is not nearly as gung-ho as the GFS. However, temperatures in the long range ECMWF are extremely low for CA–about as cold as I’ve ever seen. This could get interesting…

          • And the new 00Z GFS this evening is once again interesting. Not quite as spectacular as last evening’s, but enough to raise eyebrows regarding the potential for very low snow levels this weekend.

  • redlands

    Are those predictions of temps for Southern California ??? For me to consider it impressive highs would have to below 45 —- like 35 -40 for highs lows of 15-20 — don’t think that’s gonna happen for the valleys of Southern Calif. Its happened in Redlands, Ca — when we had the orange groves — almost all the oranges are gone replaced with houses and black-top. Those temps maybe in the Mountains

    • It’s possible that temperatures could actually rival those during the 1990 cold wave. But there’s a lot of uncertainty at the moment, so the most conservative forecast is “widespread subfreezing lows for multiple days.”

  • redlands

    Yes December 1990 in Redlands, Ca was an impressive year – temp wise — Was the coldest minimum average ive recorded for the month of December. We had 11 overnight lows with temps 32 and below — lowest being 21 — There was two impressive temps — hi 46 – low 26 on dec-21-1990 hi 50 – low 21 dec-22-1990. I don’t think we will ever get the daytime maxs of 34 and lows of 18-20 degrees — with most of the oranges groves gone

  • Pingback: Daily Digest: John Laird talks BDCP to NorCal, restoring Hetch Hetchy, precipitation watch, and more » MAVEN'S NOTEBOOK | MAVEN'S NOTEBOOK()

  • redlands

    Reading the local forecast for the San Bernardino/Riverside Valleys — it appears that we wont be hitting Dec 1990 temps . I suppose things could change to colder

  • Cliff Collipriest

    Just found your blog and the information you post is great. Very informative. The cold snap coming won’t be fun for those of us on the Central Coast, or anywhere I would think. Your comments regarding a possible shift in the MJO were a reason to be hopeful for the water starved Central Coast. I hope it pans out. WE NEED RAIN!

  • Models continue to converge on a system slated for Friday night and early Saturday, which will bring precipitation in a very cold airmass. Snow levels will probably be very low, perhaps exceptionally low. Redding has an excellent chance at seeing accumulating snowfall, and there’s a chance of snow falling below 1000 feet if things work out just right. Stay tuned…

    • Avery Smith

      Redding, Red Bluff, Chico, and Auburn all have a good shot IMO. The GFS and the Euro seem to both be on board. What do you think for folks in the Napa valley as well as for further south in the Sacramento valley?

      • Avery Smith

        18Z NAM shows RDD getting 3-5″.

      • Well, I’d say it’s not impossible. This setup–where a weak circulation in an already cold airmass wraps even colder modified Arctic air in from the north and east–is just about the only one I can envision where snow could fall at 500 feet or lower across a large part of NorCal.

        • Avery Smith

          This will be very interesting!

    • sc100

      I’d say this is the best chance of seeing valley snow since 2009. Pretty rare for us to have this much moisture entrained in an arctic outbreak that’s coming down.

    • snow755

      winter storm watch is now up for above 1000ft

      CAZ016-041230-
      CENTRAL SACRAMENTO VALLEY-
      INCLUDING THE CITIES OF…CHICO…OROVILLE…
      MARYSVILLE/YUBA CITY
      334 PM PST TUE DEC 3 2013

      FRIDAY…MOSTLY CLOUDY WITH A CHANCE OF RAIN AND SNOW. HIGHS
      37 TO 43.
      .FRIDAY NIGHT…RAIN AND SNOW LIKELY. LOWS AROUND 32.
      .SATURDAY…PARTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN SHOWERS.
      HIGHS AROUND 43.

      CAZ017-041230-
      SOUTHERN SACRAMENTO VALLEY-
      INCLUDING THE CITIES OF…SACRAMENTO
      334 PM PST TUE DEC 3 2013

      FRIDAY…MOSTLY CLOUDY WITH A CHANCE OF RAIN. HIGHS 41 TO 47.
      .FRIDAY NIGHT…RAIN LIKELY. LOWS AROUND 34.
      .SATURDAY…MOSTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN AND SNOW
      SHOWERS. HIGHS AROUND 43

      CAZ019-041230-
      NORTHERN SAN JOAQUIN VALLEY-
      INCLUDING THE CITIES OF…STOCKTON…MODESTO
      334 PM PST TUE DEC 3 2013

      FRIDAY…MOSTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN. HIGHS 43 TO
      50.
      .FRIDAY NIGHT…RAIN LIKELY. LOWS AROUND 36.
      .SATURDAY…MOSTLY CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS.
      snow showers have now been added for the valley
      HIGHS 40 TO 47.

      • sc100

        Wow, highs of 37-43 around Marysville!

        • snow755

          Friday highs will need too be watch the valley could end up getting a lot of snow if the high tempers don’t go two high

  • Will do a mini-update within this blog post after 00z models tonight given low snow potential this weekend.

  • redlands

    Is this low snow level — below 1000 for Southern California ???

    • Probably not quite that low south of the Grapevine–though still could get under 2000 feet.

  • redlands

    Is 1500 ft possible ???

    • Perhaps…though that will depend strongly on the trajectory of the low.

  • 06z NAM suggestive of a pretty widespread snow event in NorCal on day 3 followed by an extremely cold airmass. Wow.

  • Betty KC

    The Weather Channel is forecasting rain with a 50-80% chance for Dec.11, 12 and 13 (in Napa). I’ve seen this many times before and would always fizzle out. Does it look like this might have some potential? I don’t want to get my hopes up… well the 11th already fizzled out, but 12 & 13 still at 70-80%. I need to stop looking.

    • The current pattern is a very tricky one, and the numerical models we typically use for forecasts have been very inconsistent lately. There recently appeared to be a trend towards wetter weather in California as the huge and persistent blocking ridge was undercut by the Westerlies, but now it appears that conditions may remain pretty dry through at least the first part of next week. It’s possible the rain finally starts to return after December 11th, but I wouldn’t count on it. There will be a small amount of rain/snow on Friday this week, though…

  • Best estimate now is for accumulating snow down to 200-500 feet in and around the Central Valley and 500-1000 feet in the Bay Area and further northward. Frozen precip could definitely fall lower than that, though accumulations are unlikely. This means there is a good chance of some snow accumulation in Redding, Red Bluff, Chico, Marysville, Fresno, and Bakersfield; at least some flakes are possible in Sacramento, Davis, and Stockton. If precip lingers longer than expected on Saturday, there would be a chance of snow showers under 500 feet nearly everywhere.

    For SoCal, snow levels will not be quite as low–more in the 2000-2500 foot range, though could be locally lower in heavy showers. Some substantial accumulations could occur at relatively low elevations about the snow line, and here again: if showers linger longer than expected, then snow levels will drop under 2000 feet.

    Saturday night and Sunday will see an exceptionally cold airmass overspread California, with very low temperatures expected. Stay tuned!

    • Avery Smith

      00Z NAM is very aggressive with snow levels…and it is starting to get into the time period where it is pretty good with details…what do you think?

      • The NAM is definitely showing some extremely cold conditions associated with this system. My primary concern regarding lowland snow potential is the timing of the precip–the NAM suggests relatively little in the way of post-frontal activity. If there are few/no post-frontal showers, it will be hard to get more than a local rain/snow mix at sea level (with no accumulations). If the front lingers a bit longer, though, or post-frontal showers are more numerous than currently depicted, there could be some widespread reports of snow near sea level. We’ll just have to see…and hope for some enhanced post-frontal activity!

      • And the 00Z GFS, while not quite as cold, does have slightly more lingering precip behind the front.

  • Dan the Weatherman

    I still can’t believe how inactive the weather here in my area of Socal has been essentially since early October. Aside from just a couple of breezy days, there have not been any moderate to strong Santa Ana wind episodes since the one in early October, which is highly unusual to say the least. It is much colder here in Orange tonight with temperatures in the upper 40s right now, but as the cold front came through here last night, there was no rain and hardly anything in the way of wind, either aside from being a bit breezy.

    • Dan the Weatherman

      Coldest night of the season here in Orange – 46.9 degrees as of 9 pm.

  • This airmass really is pretty impressive. It’s already below freezing tonight here near San Francisco Bay! The airmass gets even colder after the Friday system passes through–there will almost certainly be some record lows set in NorCal over the next few days. I still think that the most likely scenario for Fri/Sat is widespread snow (with accumulations) above 500-1000 feet throughout NorCal and a (non-accumulating) rain/snow mix down essentially to sea level in most other areas. I’d say there’s about a 20% of more widespread snow accumulations near sea level, especially in the Central Valley. Saturday night looks like one of the coldest nights we’ve had up here in a long time–much colder even than tonight.

    • Avery Smith

      I think evaporational cooling could play a big role in this storm….if the system can overcome the dry air in place a lot of locales will start out as snow….similar to an overrunning event.

      • It’s possible–it certainly is dry out there now. I think it will also depend on how warm it gets before the cloud shield arrives on Friday. If there’s no sunshine on Friday, it’ll be hard to crack 40 in a lot of spots…

      • Once again, the 06Z NAM is impressive (the timing is more favorable). In fact, the current depiction would bring accumulating snowfall to all of the San Joaquin Valley on Saturday and would increase the chance of snow showers elsewhere.

    • Dan the Weatherman

      With dew points in the teens and 20s in most of the Bay Area, there is definitely the potential for these temperatures to drop even further, given there are many hours before sunrise.

  • redlands

    Weather Update for Redlands, Ca — Dec-4-2013 Presently its 43.6 — 72% Partly Cloudy at 1157pm High for today 58.4 low 39.8 on my Vantage Vue – fan aspirated — Vantage Pro Hi 60.2 Low 39.9 No rain Wind Gust of 10 mph. Not really impressed with this cold snap — Record for Lowest Maximum at my station for Dec-4 is 50 which happened in Dec-4-1992. Record Lowest Maximum for Dec-5th is 52 which happened in Dec-5-2004. My records go back to Dec of 1981. Interesting fact for Redlands, Ca — records by the Redlands Daily Facts — records back to 1920. Dec-12 – 1932 Lowest Maximum of 34 — that’s what I call a cold snap — having a high of only 34 in Redlands, Ca . Last time Redlands, Ca really had a good snowfall was January of 1979 — theres been a few times with snow flurries or a very thin layer of snow few years ago – but nothing like January 1979 — however 1949 takes first place concerning snowfall — 3 days where it snowed

  • Things continue to come together for a very low snow event Friday night into Saturday and an extremely cold night Saturday night. Snow is possible on the floor of the Sacramento Valley and San Joaquin Valleys, and could even accumulate away from the Delta. Snow could fall at least briefly on the North Coast at the onset of precip tomorrow, and could possibly fall below 1000 feet in the Bay Area. Above 1000 feet, significant accumulations are possible throughout NorCal. Snow levels in Socal will drop under 3000 feet, perhaps to 2000 feet or a little lower Saturday evening. Overnight temperatures Saturday night will probably be record-breaking nearly statewide, with lows in NorCal perhaps exceeding previous daily record lows by 5-10 degrees. Even coastal areas in the north could experience a hard freeze. This is all especially impressive given it’s still early December. I’ll probably have a new blog post later today given the rare and high-impact weather expected this weekend…

  • Dan the Weatherman

    It’s going to be another cold night tonight. It is already down to 51.4 degrees outside my window here in Orange and it isn’t even 6:00 pm yet!

  • redlands

    Its 40.9 at 11.11pm in Redlands, Ca dec-5-2013 — Got 0.01 of rain !!! So the month of December wont go rainless.

    • Sunchaser

      Itl’s about 41.7 @ 12:10 AM here in Glendale on 12/6/13 —- no rain here but hoping for some friday night/saturday…..Hope it pans out !!!!

  • sc100

    I saw NWS has issued a winter storm warning down to 1,000 feet east of Sacramento and also for the northern Sacramento valley. I’ll never forget waking up exactly four years ago today and seeing a winter storm warning issued for Sacramento. Absolutely blew my socks off. I think that’s the only time that’s ever happened. I actually saved the NWS graphic from that day and have posted it below.

  • sc100

    I saw NWS has issued a winter storm warning down to 1,000 feet east of Sacramento and also for the northern Sacramento valley. I’ll never forget waking up exactly four years ago today and seeing a winter storm warning issued for Sacramento. Absolutely blew my socks off. I think that’s the only time that’s ever happened. I actually saved the NWS graphic from that day and have posted it below.

    • Charlie Hohn

      Did Sacramento get snow then? i remember the davis snow in 2002, a few photos here: http://daviswiki.org/snow

      • sc100

        The far eastern part of the city did but downtown didn’t really get it, unlike in 2002. However, I don’t think any accumulations occurred in the county except in the far eastern part. The last time Sacramento actually saw an accumulating snow was in 1976.

        Also, I was in Davis for the 2002 snow and it was a pretty impressive snow at times! The pavement was just a little too warm for it to stick to it, though.

        • Dan the Weatherman

          What month in 2002 did this lowland snow occur? The 2001-02 season in Socal was one of the driest and most boring seasons I have ever seen. There weren’t any memorable cold outbreaks down here like there have been in our more recent bone-dry years like 2006-07 and 2012-13, and this year so far.

          • sc100

            It happened in late January. That was just a moderately below average year for us.

  • sc100

    Also, NWS Sac had a great discussion last night comparing the current low snow event to 2002 and 2009:

    “The question remains if the valley will see any snow and the
    chances seem higher than 50/50. The new NAM Bufkit this evening
    indicated all rain for SAC/SMF…but this is tenuous based on the
    saturation of the air mass and rapid rise of the dewpoint by the
    time it precipitates Fri evening. Given modified arctic air has
    been in place for a couple of days now in the valley with very low
    dewpoints…the case can be made that evaporative cooling will
    lower the WBZ below freezing at the onset of precitation causing
    at least a mix if not all snow in parts of the valley. For the srn
    sites…latent heat could raise the WBZ above freezing until FROPA
    early Sat morning when the precip could be in the form of all
    snow. This parallels 2009. One thing we have seen in the past as
    well as outlying areas are more susceptible to the frozen precip
    likely the result of the urban heat island. This has happened in
    many events…i.e. 2002 when the surrounding area saw snow and the
    immediate downtown area saw all rain or at times a mix but no
    accumulation. In this case…the models will struggle and the 2002
    and 2009 scenarios will play out.”

  • Avery Smith

    Redding reporting snow! Hoping Red Bluff and Chico are next!

    • Looks like the rain/snow line is currently moving into Chico. Temperatures/dew points in the S. Sac. Valley are much more marginal, though. Any mixed precip south of about Willows will have to wait until the back edge of the frontal band moves through. Snow levels are currently around 2000-2500 feet in the Bay Area and will remain roughly there for a while before dropping to around 1000 feet on the back edge of the precip band late tonight. The San Joaquin Valley could still see some snow near sea level, though accumulations will most likely be limited to places ~500 feet or higher.

  • Snow currently falling in Ukiah and some of the higher North Bay Valleys above 500 feet! Almost certainly snowing in Chico at the moment with surface temperatures ~34.

    • And apparently Highway 101 and Interstate 5 are closing due to heavy snowfall in Ukiah and Redding, respectively.

    • Snow in Red Bluff and Oroville.

  • redlands

    No rain or snow in Redlands, Ca as of 915pm — temp is currently 46.7 — clouds above

  • snow755

    snow is falling here in sonora CA and here on greenley rd i live right on the top of greenley rd at 100 greenley so far i pick up a light dusting road are clear for now but wont stay that way for long

  • redlands

    How high is Sonora Ca

  • snow755

    Snow is sticking too ever thing now I now have a dusting roads have gone down hill

  • sc100

    Snow getting close to the Sacramento County line right now. Eastern suburbs should see some snow. It’ll be interesting to see how far west the snow goes!

  • Snow now falling down to 500 feet in E. Sac. suburbs. Also, looking at North Coast radar and satellite imagery, there may be more shower activity associated with the low center than previously expected. These scattered showers would fall as snow…

  • Snow now falling down to 500 feet in E. Sac. suburbs. Also, looking at North Coast radar and satellite imagery, there may be more shower activity associated with the low center than previously expected. These scattered showers would fall as snow…

  • Redding has apparently received nearly half a foot of snow this evening, which may be among the all-time record snowfalls in that location (it certainly beats the previous December record). Snow levels rapidly falling behind the cold front, and hi-res mesoscale models depict widely scattered showers for the rest of the night into Sat. AM from the Bay Area into the Central Valley. These will fall mostly as snow. Still waiting to see if the Fresno area gets snow later tonight, and it is certainly still possible.

  • Flunking_retirement

    46 in San Diego this morning, with 80% chance throughout, that’s the highest we’ve seen since late October. While we southern So Cal-er’s naturally take high PoP’s like that with a spoonful of salt, at this moment it does look promising from the northwest.

  • snow755

    I have picked up 5″ of snow

  • redlands

    So far this artic blast has been a flop in the Redlands, Ca area — as of now no record temps — only 0.03 of rain — no snowfall or high winds . I know some areas up in Northern Calif have received low-level snow — nada down where I live

    • Sunchaser

      As of 3:00 PM — 0.07 of rain — here in the South East part of Glendale with a temp of 51….definitely a flop as well….and looking forward doesn’t look good either…..

    • It was certainly an interesting storm up here, but in the scheme of things brought very little moisture. We didn’t even reach normal precip for the WEEK, and it does look pretty dry going forward. It really is starting to look like a dry December will close out our driest calendar year on record…

  • Flunking_retirement

    Just got a nice shower, Id guess maybe an 8th to a 5th an inch. That makes the second decent rainfall this year so far for SD
    .

  • Dan the Weatherman

    It is definitely colder here in Orange tonight in the wake of today’s storm. It is 40.6 degrees as of 2:15 am (early 12-8-2013)

    • Kamau40

      Dan,

      Looking at the latest long range climate computer models is looking bone dry from now right thru at least the first 3 weeks of Jan. We are indeed off to a very bad start to the new water year. Yikes!!

      • I’m not too sure how much we can say about January at this point (the CFS has only modest skill around here at this time of year), but I’m certainly not very optimistic about the rest of December, and I see no especially promising signs for January. It seems that the recent MJO activity is not affecting the flow pattern in the typical way, which means we may miss our next best opportunity for more precip.

        • Dan the Weatherman

          It seems like nothing can break this persistent NE Pacific / Gulf of AK ridge pattern down for some strange reason. Something is constantly reinforcing this ridge over and over again barely letting any variability in the pattern to occur except for a cold outbreak like this. We just can’t seem to get storms to come in from off the Pacific as they often do during a more normal winter weather pattern.

          • Kamau40

            That is what makes me worried about yet another bone dry winter. I know we have a long ways to go, but the fact that we are not seeing any hints of storms down the road, which we should be at this time, is making me very nervous. The Eastern Pacific ridge is just locked in rocked solid. Remember, the later we get in the rainy season, which is very short, the more difficult it will be to make it up.

          • Dan the Weatherman

            This reminds me of the weather pattern that dominated much of last winter. I don’t know if I ever have seen a ridge pattern as resilient as the one we are currently experiencing. We have had many drier years in the past, but at least the pattern would change for awhile due to some shorter term feature such as a favorable MJO and bring a stormier pattern for a week or two before turning drier again. With this current pattern, a change is very short, only allowing a small storm or two to hit the area, and the ridge bounces back again in no time flat. It is as if there is some other forcing mechanism at work that is constantly perpetuating this recent cold and dry pattern.

  • Very impressive cold today and tonight in NorCal. Highs are struggling to make it out of the 30s in parts of the Central Valley, and mid-afternoon temperatures are generally in the low 40s in the Bay Area. Tonight will be extremely cold, with widespread lows in the low 20s near sea level. Some areas will drop into the teens, and even the immediately coastline will drop below freezing (these will be record-breaking daily low temperatures). Overnight lows will remain very cold for several more days while daytime highs moderate. The next 7-10 look exceptionally dry once again for mid-December. Will have a full update after 12-11 when the November precipitation rankings are released–I expect the year-to-date will remain the driest ever here.

  • snow755

    Sonora has pick up .23″ with the snow that fell. Why twain hart CA has pick up .27″. So the snow is meting a way now but vary slow. I wounder. What .23″ and .27″ would mean in snow fall Any snow re ports from twain hart?

    • Flunking_retirement

      Figure 10 to one for snow. .27 = roughly 2 3/4 inches.

      • snow755

        Thanks!

  • redlands

    Thats not good no rain up till Jan-2014

  • Dan the Weatherman

    .18″ fell here in Orange yesterday. It was a rather cool day today after I recorded the lowest temperature of the season this morning of 39.2 degrees. It is currently 41 right now as of 1:25 am. Some strong Santa Ana winds are forecast for later tonight and especially tomorrow (Monday), but it is still fairly calm here.

  • sc100

    Man, things look absolutely horrible from here on out.

  • Pretty hard freeze here in Palo Alto last night with a low of 22 (!). Anyway, nothing coming down the pipe for the foreseeable future. Will do an update on the drought by the end of this week…

  • Flunking_retirement

    Cold night for San Diego anyway, 45 this morning. Its up to 60 now getting a chilly santa ana – winds are southeast 15 to 20 sustained, gusting to 25. high clouds coming in look to be about 20 to 25k visibility 10 mi plus in light haze.

  • Flunking_retirement

    Morning watch at NWS San Diego gets the creativity gold star this morning for a 300 word essay saying “its going to be chilly and windy for the next 5 days”.

  • After checking the stats, it would be very hard for 2013 not to be the driest calendar year on record in California. In some regions like the Central Coast and Bay Area, we would have to receive 10-30% of our average ANNUAL precipitation between now and the end of the month just to break even with the previous driest year. And there’s no significant rain in the forecast for at least the next 7-10 days, and very possibly beyond.

    • sc100

      As far as how Sacramento is faring, we have 6.11 inches for 2013, just 0.56 inches below the record of 6.67 inches in 1976. Looks like we have a good chance of breaking the record. We’ve actually only had 6 days of precipitation this rain year. Two days in September, two in November and two so far this month. Mind numbing.

      • Dan the Weatherman

        Boy that total is dry for your area! That is even dry by Socal standards.

        • Charlie Hohn

          I feel like calendar year rainfall measurements are mostly meaningless, but this is a big deal. In a bad way. 🙁

          • Certainly the interpretation of calendar year vs water-year metrics in a cool-season dominated region like California requires caution. In this instance, the calendar year is important because it spans the second half of the previous water year and the first half of the new one, and both of these periods have been truly exceptionally dry. The only reason why last year wasn’t worse from a water year perspective was because of the exceptionally heavy but fleeting rains in late November, which didn’t have the same water storage benefits of a more distributed precip event.

            1976-1977 was an extremely dry water year, though the calendar years of 1976 or 1977 weren’t nearly as extreme. Here, we’re actually in a similar situation, but this time the extraordinarily dry “water year halves” occurred in the consequent halves of different water years rather than in the same water year spanning calendar years.

            In any case, we’re already developing pretty incredible precip anomalies for the 2013-2014 water year. If the rest of December is as dry as current forecasts suggest, we’ll be in very bad shape heading into calendar year 2014.

          • In fact, the current 12 and 24-month periods are now the driest since 1977 (up until the end of November). Since the present December is shaping up to be even more anomalous, we’re on track to surpass that pretty soon.

          • Dan the Weatherman

            Do you think the winter months (January – March) are going to be as anomalously dry as this fall, or do you think we will finally see a shift in the pattern to bring some bigger storms into the area?

  • After a week of record lows and low elevation snowfall, there now appears to be a pretty good chance of record highs across parts of California next week!! Even more impressive is that these huge swings in temperature will still not be associated with any precipitation. Expect a full blog update tomorrow…

    • Kamau40

      I’m looking out as far as I can see and it is bone, bone dry.

  • Pingback: The extraordinary California dry spell continues: 2013 will probably be the driest year on record | California Weather Blog()

  • New blog post!