Enhanced El Niño storm track has finally emerged; Active pattern likely throughout California next 2-3 months

Filed in Uncategorized by on January 17, 2016 5,902 Comments

Notable “parade of storms” continues over Eastern Pacific; heavy rainfall & some flooding across Northern California

In my last blog post, I discussed an imminent “parade of storms” that was slated to begin during the first week of the new year.

California is presently a 50/50 patchwork of above and below average precip for the season. (WRCC)

California is presently a 50/50 patchwork of above and below average precip for the season. (WRCC)

Over the past two weeks, a series of strong and moist storm systems have brought wet and occasionally hazardous weather conditions to different parts of the state. Two major low-latitude storm systems affected Southern California during the first week of January, bringing widespread heavy precipitation and flooding of varying severity. The most remarkable part of these early January systems, though, may have been the intense convective activity associated with them. Widespread thunderstorms–some of them severe–brought significant flash flooding, damaging winds, and even a couple of tornadoes. These two storms–characterized by ample atmospheric moisture, unusually high atmospheric instability, and excellent jet stream-level forcing–were highly reminiscent of the more memorable Southern California storm events during the 1982-1983 and 1997-1998 El Niño events.

Since that time, Southern California has dried out considerably as the Pacific storm track shifted northward. But it hasn’t shifted nearly as far north as during recent drought winters–the Pacific firehose has instead been aimed squarely upon the northern half (and especially the northern third) of California in recent days. Impressive double-digit rainfall totals have already been observed, and still there is much more to come in the coming days.

The GFS ensemble shows high confidence in heavy precipitation as far south as Monterey County over the coming 7 days. (NCEP via tropicaltidbits.com)

The GFS ensemble shows high confidence in heavy precipitation as far south as Monterey County over the coming 7 days. (NCEP via tropicaltidbits.com)

In fact, several major North Coast rivers are currently approaching or exceeding flood stage, and sections of the Sacramento River may exceed flood stage as well over the next few days (in any case, the weirs will certainly be overflowing). Meanwhile, snow accumulations in the Sierra Nevada have been equally impressive, and are the best in years (110% of average to date, a number I expect to rise further this week). Right now, all of this water in Northern California is very good news. Enough precipitation is falling to generate significant runoff without greatly exceeding the capacity of river systems to manage the influx (most flooding to date has been relatively minor in NorCal). Conditions have been cool enough for this precipitation to fall as snow at the higher elevations, meaning that California’s critically important “snow reservoir” is starting to fill. There’s still a lot of empty space in Northern California’s man-made reservoirs and natural groundwater aquifers, but at the moment things are moving in the right direction from a drought relief perspective.

A classic El Nino pattern has emerged over the northeastern Pacific. Note the absence of persistent ridging over California/the West Coast. (NCEP via ESRL)

 

Strengthening and “straightening” Pacific jet stream, characteristic of strong El Niño events, now in place

I’ve discussed on numerous occasions that the main mechanism by which El Niño affects California winter precipitation is by enhancing the subtropical jet stream over the far Eastern Pacific. As the jet strengthens and shifts southward, it effectively “straightens” out in the vicinity of California–reducing the amplitude of its typical northward bend that can often cause storms to veer northward into the Pacific Northwest or weaken before reaching California. This past autumn, an enhanced Pacific jet stream did indeed develop, but it was located well to the north of the Golden State (and brought record-breaking rains & floods to Seattle and Portland). Since the fall, though, this El Niño-strengthened jet has shifted gradually southward. The enhanced Pacific storm track is now consistently soaking Northern California, and bringing more transient soakings to Southern California. For reasons relating to the intrinsic seasonal cycle of the Pacific jet stream, I would expect unusually wet conditions to continue to expand southward along the California coast in the coming weeks. In fact, a quick glance at how upper-atmospheric conditions have changed since the autumn shows a striking transition towards a classic El Niño pattern over and west of California, with a roaring subtropical jet and a large negative geopotential height anomaly over the northeastern Pacific (yet more confirmation that the Ridiculously Resilient Ridge is outta here).

Animation showing shift from autumn to January pattern. Note the pronounced El Nino-related strengthening of the subtropical jet. (NCEP via ESRL)

Animation showing shift from autumn to January pattern. Note the pronounced El Nino-related strengthening of the subtropical jet. (NCEP via ESRL)

 

Yes, the southern third of California has thus far experienced below-average rainfall so far this season. But…

There continues to be much consternation regarding the fact that parts of Southern California remain well below-average precipitation-wise for the season to date. It is certainly understandable, after consecutive years of abysmal rain seasons, that drought-related anxieties are running high. And it’s interesting to note that one of the relatively driest spots in all of California so far this water year is Los Angeles County–which comprises a considerable fraction of the state’s population. But nearly all of California has fared better than Los Angeles County so far this season–and prospects for significant Southern California precipitation remain high in the coming weeks. It’s important to remember than California’s rainy season is relatively short and sharp (particularly in the south), and that the vast majority of precipitation falls over the course of a handful of heavy precipitation events (like, for example, the early January storms). Even during California’s wettest winters, most winter days are dry in Southern California–and multi-week dry spells occur virtually every winter. It’s also true that many of Southern California’s wettest seasons were primarily the result of only 1-2 very wet months. Thus, there is plenty of time for Southern California to catch up–and exceed–average precipitation this winter.

 

Pacific jet extension likely over next 1-2 weeks; enhanced precip should expand southward by end of January

A lot more rain is in the forecast for Northern California over the coming 7-10 days (perhaps more than 10 or even 15 inches in orographically favored parts of the North State, and more than 6 inches in the coastal mountains as far south as the Bay Area). Then, during the final week of January, there is an emerging model ensemble consensus that an burst of jet stream energy from the West Pacific will propagate eastward across the entire basin, forcing the Pacific storm track southward from Northern California and bringing enhanced precipitation to the entire state. Such an active jet pattern makes pinpointing the details nearly impossible more than a few days in advance, but there are early signals of a situation potentially similar to the one we experienced in early January.

The CFS suggests that a very active pattern will develop across all of California by late January. (NCEp via tropicaltidbits.com)

The CFS suggests that a very active pattern will develop across all of California by late January. (NCEP via tropicaltidbits.com)

Flood concerns will grow across Northern California as soils are now completely saturated from days of heavy rainfall. With a substantial snowpack, any warm “Pineapple Express”-type storms could pose a risk of snowmelt-related flooding. If storms can remain relatively well spaced-out, it’s entirely possible major flooding may be avoided, and that the upcoming very wet period will be almost exclusively beneficial in a drought-stricken state. But California is no stranger to getting too much of a good thing, and the potential for that to occur is rapidly increasing as watersheds finally reach saturation capacity for the first time in several years.

 

Powerful El Niño still in place; maximum Southern California impacts likely still to come 

Very high ocean temperature anomalies persist in the equatorial Pacific Ocean. (NOAA Coral Reef Watch)

Very high ocean temperature anomalies persist in the equatorial Pacific Ocean. (NOAA Coral Reef Watch)

Interestingly enough, our record/near-record strength El Niño event is not going away without a fight. In fact, one of the strongest westerly wind bursts on record–apparently exceeding most of those during the infamous 82-83/97-98 events–occurred just last week. While Nino 3.4 sea surface temperatures have likely reached their peak, very warm equatorial ocean temperatures may persist even longer than initially expected and will certainly continue for the rest of winter and likely most/all of spring. Further, El Niño’s impacts in California tend to lag peak ocean temperatures by a month or two. Thus, the rest of January through March (and perhaps even April or May) will be prime time for increasingly prominent El Niño effects–including a greatly enhanced subtropical jet stream and periods of enhanced storminess and heavy precipitation throughout California (yes, this includes Southern California). Stay tuned!

 

© 2016 WEATHER WEST

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  • DML

    Winter storm Frona on December 17, 2008 was a blast here in the high desert.

  • jptimmons

    Woohoo! My girlfriend just woke me up from a nap yelling the magic word, “snow!” WeatherUnderground bumped up the predicted snow amounts today in Burney to 1-3 inches, we’ve had a little bit of everything today; clear skies, hail, snow and rain.

    • Scap

      Did you get any snow last night? How is the snow cover around the surrounding area? I’m thinking of visiting my grandparents and snow shoeing in that area.

      • Crank Tango

        Nothing on the ground below 5k feet in Burney metro area. I sometimes go up hatchet mountain (bunch grass Rd) if we don’t get any in Burney. Whereabouts are you staying? Eskimo hill near old station is a good bet too.

        • Ventura Highway

          Burney metro area, I like that, heh

        • Scap

          Cassel. The square log cabin on hat creek is my grandparents. Kind of by where they stock the fish just past the corner a bit.

          • Crank Tango

            I just went up to Eskimo Hill and there was plenty of snow–a good crust a couple feet deep and some fresh powdery snow on top and it was snowing hard when we left.
            If you take 89 from cassel you will see snow from old station on pretty much.

    • Crank Tango

      Ha! Fingers crossed.

  • hermit crab

    So the forecast discussion says the much-awaited SW flow has moved to below Santa Barbara county. Wondered how certain that is. NW flow in Carpinteria, btw, is prohibited.

    • AN50

      Yup, these outside sliders are no bueno for the south coast. Although you guys in carp look like you are on the higher precip side. Keep yer fingers crossed.

      • hermit crab

        I’m so used to being on the lower side, this year 🙂 will see what happens!

  • Animal Style

    Daytona Beach, Florida has 7.05″ inches of rain this January! Their Jan average is 2.74″. That is 257% of normal!

  • Boiio

    At least the models agree on something! Excuse me while I bang my head against a wall…

    • IDK (Santa Barbara)

      Eww a ridge. The Euro one is further north so maybe the jet can undercut it?

      • GR

        Ridges are inevitable. The question is the stability.

      • SlashTurn (Santa Barbara)

        I see this as a positive. It may be a true precursor to a full blown westerly breakthrough later on.

      • WanderingTattler

        Just checked the jet stream – no longer split and barreling over the length of CA.

    • Nathan

      On the plus side, can probably finally go diving next weekend.

  • 310weatherguy

    This storm better give what its been indicating at..

  • Animal Style

    WU is increasing my rain total again!

  • Fairweathercactus

    WU just put up the strong thunderstorm icon up with the red bolt of lightning and 1.02 for tomorrow.

  • TruckeeLover

    Really interesting cloud formation over San Luis Obispo right now!

  • SoCalWXwatcher

    Latest rain forecast from NWS Oxnard. This will be the first storm with decent totals South of Point Conception since those storms we got at the beginning of the month:

    https://twitter.com/nwslosangeles/status/693586001852108800

    • SoCalWXwatcher

      And it looks increasingly likely that LA could tie or exceed it’s January 1998 total from the last big El Niño season.

    • weathergeek100

      A solid inch for downtown LA? That’s great news:)

  • Bandini

    The snow that just started falling is great quality; light, fluffy, cold and accumulating quickly. Potential great day in the mountain tomorrow.

    I went and took some shots of the Yuba and the Truckee today. Even after the deluge yesterday, the snow pack still looks great, especially from Big Bend to Soda Springs, and Truckee still has plenty. Winter Weather Advisory hoisted for tomorrow. Ye ole Tonopah Low?

    • maddogokp

      Just started snowing in the Shire.

      • Bandini

        Tomorrow might be great. I held off today, figured all that rain yesterday covered by a few inches of snow could get ugly. Did you shred Sugie?

        • maddogokp

          No, blacked out at Sugie. So I gave Donner Ski Ranch a try. I was not expecting much, but was really pleased. 6″ of fresh made for some great turns on the backside all afternoon. Thinking Squaw tomorrow, I don’t think they opened Granite or Silverado today. BTW great river pics, lots of water around town.

          • Bandini

            I’ve been pleasantly surprised with the Ranch this year. 7 days up there so far, and all powder days. I’m sure normal days just cruising groomers there would get boring quick, but I got vouchers for those days at the big resorts.

    • Rams (HMB/Truckee)

      Great pics and the water is awesome….so great to see the pack still in place and so much more water moving! Thanks for sharing

    • weathergeek100

      Wow. That easily looks a foot deep at least. I’d imagine with such a rainstorm you guys got yesterday, a much bigger chunk would’ve been taken out. This is good news that there’s still plenty of snow up there.

    • TahoeCard

      Homewood was fantastic today. 10″ of fast riding powder. Impressed with how well the pack absorbed rain.

      • Pfirman

        Sweet words, ‘the pack absorbed rain’.

  • Boots

    Out at Lake Casitas today. It was the proverbial calm before the storm. In the summer of ’98 I used to tie my boat off to those trees at the top of the picture. Lake Casitas has fared better than its neighbor to the north Lake Cachuma due to the fact that it’s a deeper lake with less surface are. Hopefully we can make a dent in it tomorrow. Fingers crossed

    • AN50

      The heaviest precip is forecast to hit you guys down there, as the surface low is predicted to drop further south. Not a biggie for us, but VTC, LA and OC should get good rain outta this one and maybe a twister or two.

      • Boots

        Hoping for 2+ inches and some dynamic storm cells!

      • SlashTurn (Santa Barbara)

        No love for the 18z NAM and the better dynamics for SB county?

        • SlashTurn (Santa Barbara)

          LP south facing slopes will be productive

    • Ventura Highway

      Any bass biting ?

      • Boots

        Very slow on the Bass, but I heard some trout were biting probably left overs from a plant a couple weeks ago. Gotta love those Lassen zombie trout. They’ll bite on anything you throw at ’em.

        • Ventura Highway

          Bass will be biting soon !

        • Admode (Susanville)

          Ever fished Eagle Lake?

          • Archeron

            YES!!! Used to go there every year camping with family! That lake is not looking so hot now, due to the idiots that were draining it =/

          • Admode (Susanville)

            I wouldn’t call them zombie fish that will bite anything in that lake.

    • John Curtis

      Thanks for the photos. I haven’t been over to the lake in a while. Wow it is low!!

    • Wet Line(San Diego)

      Nice pictures, still looks way to dry out there. I hope you get a good soaking to start filling those lakes and to green up the vegetation.

    • hermit crab

      Thought Cachuma would get some help tomorrow but now I am not sure. I will have to go to Casitas and fill buckets

      • AN50

        Yep we’re gonna miss the big stuff tomorrow then its two weeks of dry, dry, dry.

        • hermit crab

          And yet we need it more than most. I still think a curse is a possible explanation 😉

  • craig matthews(Big Sur)

    Enjoy the storm Socal. Looks like its shaping up to be a dandy for you guys

    • DelMarSD

      It’s looking quite dandy indeed.

    • WanderingTattler

      Thanks – looking forward to Daniel’s explanation of it.

    • So excited!

    • hermit crab

      Will Carp get:
      0-.09
      .10-.19
      .20-.29
      .29-.49
      .50-.74
      .75-1.00
      Over 1.00 inches

      Betting open now
      ?

      • Fairweathercactus

        Cactus bets 0.50-0.74

      • matt (truckee)

        Over 1″. Go big or go home!

      • TruckeeLover

        I’ll take the over 1 large…for sures!

      • Tyler Price (Van Nuys)

        1.13 inches!! Lol! ?

      • weathergeek100

        Over 1″!!!

      • Microbursts

        You heard it here first … Carp gets 1.25 inches !! Thanks to a strong finish !!

    • Wyomg

      very excited here in san diego

  • weathergeek100

    All rainfall totals significantly increased across SD country and throughout. Exception is LA where it’s actually slightly lower.
    https://scontent-sjc2-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/12642814_1146334932045168_8506021926715170918_n.png?oh=e3c8815a4716cfb2237b663a09583eda&oe=572EADCB

    • DelMarSD

      Looking great!

  • PrimeMover

    NWS Reno mentioned a ‘hybrid Tonopah low’. Living in the Owens Valley (Bishop) i have seen a few of these over years not often but a few and a ‘Tonopah low’ can lay some serious snow down in the valley.

    What does’ hybrid Tonopah low ‘mean and I’m curious why NWS Las Vegas didn’t mention it in there forecast. We sure could use it over here. We’ve been seriously Rain Shadowed this winter.
    Current storm 0.03″

    • Pfirman

      In plants and animals, hybrid means vigor. In weather, it probably means you’re screwed out of whatever you were looking for, but I would not plan a picnic.

  • 805 Weather (Camarillo)

    NEW UPDATE FROM DANIEL 🙂 http://weatherwest.com/archives/3822

  • Sumster

    What is with theseveral CPI guys? They post the same chart over and over, it never seems to come true. I guess a broken clock is right twice a day. Maybe Patzart is on their team 🙂

  • Sumster

    Oops…CPC….not CPI

  • Jeff

    Ha Ha Ha Ha, nice prediction re: Active pattern through March/April
    The only thing active in SoCal is the forever lasting drought.
    SoCal is over as a destination, without water in the lakes, reservoirs, etc!