NorCal deep freeze on Tuesday; rain returns on Wednesday: winter has finally arrived in California

Filed in Uncategorized by on January 16, 2012 202 Comments

Well, it does certainly appear that the remarkably quiescent and dry weather pattern that has persisted nearly throughout California since November is finally coming to an end. After more than two months of extremely dry conditions during what is normally the height of the rainy season, nearly the entire state has accumulated some truly impressive precipitation deficits. Most of Northern California is experiencing hyrdological drought according to NOAA’s Palmer Drought Severity Index, with a good portion of the Sierra Nevada squarely in the “severe drought” category. Fortunately, though, these metrics are based primarily on short to medium-term soil moisture, which (as those who have lived in this state for more that a few years already know) can change quite quickly under the right circumstances. And it starting to appear that conditions may be right for some very significant precipitation over the next 10 days.

(NOAA/NWS)

First things first, though: a very cold Arctic airmass has invaded the Pacific Coast of North America over the past few days, bringing snow all the way down to sea level in Washington, Oregon, and even briefly on the beaches of the far north coast of California. The entire state of Washington, and much of Oregon, are expected to receive heavy and possibly record-setting lowland snowfall over the next 3-4 days, with accumulations exceeding 12 inches possible all the way down to sea level near Seattle. While California is unlikely to see any extraordinarily low snow levels this week (outside of the possibility of a few more flurries along the far North Coast early Tuesday morning), a long-duration (and possibly record-setting) deep freeze is already underway across much of NorCal this evening. Temperatures by 11 PM had already dropped into the 22-27 degree range across large parts of the Sacramento Valley and were already below freezing across much of the Bay Area. With dewpoints mostly in the low 10s, record low temperatures are likely across large portions of NorCal on Tuesday as surface temperatures drop into the low to mid 20s in most locations and even as low as 12-17 degrees in the coldest valleys, even near sea level. In short, tomorrow morning will be very cold by NorCal standards, and there will probably be some agricultural damage and perhaps even some burst pipes as a result.

These cold temperature, though, will not last long. By Wednesday, warm and very moist air will initially override and eventually displace the cold and dry Arctic airmass over California as a strong zonal jet–yes, finally, a strong zonal jet!–noses into the far northern part of the state. Rain will begin slowly over far NorCal on Wednesday and spread southward through Thursday, reaching the Monterey Bay Area by late in the day. PWs over 1.5 inches are associated with these incoming systems, and there will be a moderate low-level jet acting to squeeze out some fairly high precipitation rates over the Coast Ranges and the Sierra Nevada. This sort of precipitation will be highly beneficial, since rain rates will not be high enough to cause any flooding problems but accumulations will be rather significant, perhaps on the order of 2-4 inches in the higher elevations, with 1-2 inches elsewhere. A similar storm is expected to arrive by Friday and drop a similar amount of precipitation across NorCal. The first storm probably won’t make too much headway into Southern California, perhaps bringing some light rain, but the second system will probably bring at least some precip to the entire state.

Probably of greater interest is the possible evolution of the pattern days 7-10. The extended forecast models–and the GFS in particular–are showing early indications of what could be a very significant precipitation event on Day 8. It appears that a large and deep cyclone off of the Washington and B.C. coasts may set up a long and deep band of subtropical moisture convergence somewhere along the Pacific Coast. With the presence of a very strong zonal jet (and also a low-level jet enhancement near the coast), this is a setup that has the potential to produce heavy precipitation where the moisture plume hits the coast. The 00z GFS focuses this plume on Central California, bringing very heavy 48-hour precip totals to the Bay Area next Tuesday. This is still over a week out, and very much subject to change, but it ‘s worth keeping an eye on considering the soil-saturating rains expected over the next 7 days over the northern 2/3 of the state.

(NOAA/NCEP)

In any case, one statement can be made with very high certainty: winter is, at last, on our doorstep. Stay tuned.

© 2011 WEATHER WEST

  • coldspot

    Wow! A winter storm watch for us tomorrow night, no way! Medford NOAA predicting 9-12″ of snow by Monday. Is it the 1st of April ? And this is a joke? Well I certainly hope it happens I’ll let you all know how it pans out. Sounds unsettled all week up here.

  • redlands

    Still dont have a good feeling bout the coming storms — the forecast doesnt seem too confident either

  • alan

    Got an inch of snow out of yesterdays system, didn’t expect anything more than mountain fog so i’ll take it!

    NWS calling for “several inches” of snow monday/monday night, hope it pans out….

  • Dan the Weatherman

    It rained just enough here in Orange to get the streets a bit wet, but nothing measurable in my gauge. This had better change soon as I have had only 2 storms with measurable rain since mid December as this winter has been one big disappointment so far.

  • redlands

    Well – my station in Redlands, Ca wont go dry for the month of February — we received a whopping 0.01 of rain today 2-12-12 — still under 3.00 for the 2011-12 rain season —- Like Dan said above — been a real disappointing season –

  • Ken K.

    Picked up .03 so far at the house. .01 yesterday and a huge .02 today. Tomorrow looks a little more promising, maybe a Thunderstorm in the afternoon, still no big rain producer. Take what we can get.

    • redlands

      Ken- your hogging all the rain down in Granite Hills — Can you share an 0.01 up in Redlands, Ca —- So i could be at 0.02 for the month !!!! How much do u have for the 2011-12 rain season ?? I have 2.94 of rain for 2011-12 season

  • coldspot

    Dismal is all I can say. Winter storm watch was downgraded To a winter advisory and they should have dropped that as well. Only got 1/4 inch of snow at the house. And a disappointing .09 of rain. The hope might might lay with a storm for this upcoming weekend, but I’m not holding my breath.

    • sc100

      Sorry to hear about the flop. At least the Sierra got some decent snow. Up to a foot in some spots. Here in the Sacramento area people picked up .25 to .50 inches.

  • Nicholas

    This storm is flopping out nicely. I think the only area that got moderate/heavy rain was around Oakland.

    • Dan the Weatherman

      Once again, just enough has fallen here in Orange so far just to barely get the ground wet.

  • alan

    Hey guys no complaining on this one ’till the morning, the storm hasn’t even come through our area yet :) , NWS @ 131pm still holding to there quarter to 3/4″ rain and 4″ to 8″ snow above 5k, i don’t see that, but maybe a few inches of snow….

  • redlands

    When is the storm starting ????? no rain in Redlands

    • alan

      later this evening, have you felt the winds pick up? They have here in Rancho Cuc.

  • Dan the Weatherman

    The big question is: are we ever going to get a significant storm to come through for us this winter or early spring season, or are these puny little storms all we are going to get much like as in 2001-2002 or 2006-2007?

    • alan

      Exactly Dan. Not a single significant storm here this season. Even in a bad year we would have had even just one storm that dumped 24″+.

      All of the past five winters (sorry that’s as far as my personal record keeping for this location goes) have given us at least 6 feet of snow by now (sorry last year was just two feet of snow BUT an extra four feet of RAIN so that years gets a pass) and two of the years had back to back snow storms in early Dec that dumped 5′ to 7′ in just a few days.

      That’s what I expect, around here we don’t call it a storm unless it’s at LEAST 12″ of snow, and we haven’t even had more than 5″ in one day……

      …..Ok, rant over, did i mention it is snowing heavily right now? :D Redlands, you had to have gotten some of this, it was dumping rain all along the 210 and had some hail in rancho c.

      • redlands

        Alan – We only got 0.01 of rain today round 5pm — tired of these flop storms —- So far 0.01 for 2/12 and 0.01 for today 2/13/12 for the monthly total of 0.02 — for the 2011-12 rain season only 2.95 —

        • sc100

          And unfortunately it doesn’t look like it’s going to get better anytime soon.

        • alan

          These areas are just 5 miles or so north of you Redlands, it was quite a downpour

          DEVORE 0.67
          CAL ST SAN BERNARDINO 0.30

          • redlands

            i wish we could of gotten 0.30 or 0.67 like Devore

  • alan

    picked up 5″ snow, mostly grauple type snow, sadly this is tied with the strongest storm of the season, 5″ is the most we’ve gotten at one time…..

  • Nicholas

    I got the worst of it yesterday with an amazing 0.00. This might be the February where I go 0.00

    • alan

      you won’t, but it’ll probably be under 1″

      Wed. is looking good for you Redlands!

      Your have excellent record keeping Redlands – you’ve recorded 2.95″ to date, so far is this almost the driest year? Top 5 at least….

      • Dan the Weatherman

        Another whopping trace fell here in Orange yesterday, as this area continues to get shafted just as much as Nicholas’ neighborhood. Come on, Mother Nature, bring us something more substantial, please! I’m getting tired of this excessive dryness!

        • Dan the Weatherman

          The problem is that these storm systems are taking an inside slider track with northwesterly flow over the area. Parts of L.A. and Orange County just don’t get much in this flow pattern due to downsloping from the mountains to the N and NW. San Diego County, on the other hand, benefits more because the NW flow is coming in from off the ocean carrying more moisture with it to squeeze out more shower activity.

          • alan

            I’d like to see baja / northern mexicos rain totals for the season and how they stack up to their average. I would have said they are above average, but we’ve now had just as many inside sliders that never hit mexico as outside sliders that went straight into mexico…

      • redlands

        Alan — The driest I’ve recorded was the 2001-02 rain season when i only got 2.78 of rain — This season is currently the 2nd driest — 2011-12 with 2.95 — 3rd place is 2006-07 with 4.30 4th place is 1998-99 with 5.02 — 5th place is 1999-00 with 6.13. The rate were going only getting killer storms – i mean flop storms producing 0.01 — we have a good chance to stay at the 2nd driest rain season —

        • redlands

          I looked at the forecast for the San Bernardino Valley — looks cool — they predict 35-43 tonight and highs on Wed at 47-56 — I dont think were gonna get down to 35 — – lowest i think we will get is 39-40 — The rain amounts — dont think we will get much — thinking 0.10 tops — hopefully am wrong

        • alan

          Wow, yeah this is about as bad of a start (and middle) to winter as it gets huh! I think we’ll do better than 4.30″ in Redlands, but maybe not 6.13″, so i would expect a top 5 for you, well right at 5 i would say….

  • Ken K.

    I feel fortunate, we picked up .54 yesterday into this morning, at the house (Granite Hills) It was raining pretty good this morning around 4 AM. This puts us over 6 inches, I have not had time to get the exact total for the season. I hope you all get some good rain and snow tomorrow. Forecast is for snow down to 2500 ft by tomorrow night. Alan this storm could be your be your biggest this year if it pans out. Redlands you are over do.

    • alan

      I hope so, and it certainly feels like it, clouds this morning are low and thick, fog sticking to the mountain from 3500′ to 6000′, slow going, and the IE is shrouded in dark ominous clouds, a nice start to the day and a setup we haven’t yet seen this year. And with such cold temps, -28C @ 500mb, snow levels are expected to quickly drop to 3000′ and lower this evening which will bump up my snow:water ratio quite well @ 6200′….

  • PacificStorm

    Picked up a coating of hail, sleet, and snow earlier along with a decent amount of lightning strikes and thunder.

  • Nicholas

    Man is it bright outside. Not sure if anyone has ever noticed when you get just enough rain to wet the ground and grass and the sun comes out right after. That is what just took place and everything has quite the glare. I think I just got about 0.01

  • Tom in San Diego

    Ken, looks like SD drew the long stick this year.

    Latest email from home says we got another half inch in Imperial Beach.
    a8!,’/ and muggy in over here (Taiwan) yesterday. They are having a cool r(:ny yri\ter.

    MARCOMSAT6C61452CH15USB/150914ZFEB12

  • Nicholas

    Getting the most heavy rain of the season so far at the moment. Also had a gust front move through as well.

  • Nicholas

    Wow what a surprise I just got about 2 min worth of hail.

  • alan

    Mountains getting hammered! Finally!

    I was impressed to see temps @ 43F in highland/san berdoo @ 2:30pm. After heading up it quickly dropped to 39 and @ just above 2000′ snow was starting to mix in! Only 2nd time @ that elevation in the past 4 years, and by 3000′ it was all snow. Sittin’ @ 27F here @ 6200′ now with a good 6″ snow from over the past 4 hours, high winds are leaving drifts upwards of 24″ and it’s not letting up at all yet :D

  • Nicholas

    Not sure how much rain fell but its been very heavy today with the streets flooding. Well look at my bucket when I get back.

    • Dan the Weatherman

      Finally, we got some rain in Orange that had some staying power! It rained steadily for a good portion of the afternoon and I know it’s measurable this time around and more than a trace. I will post a total later on when this storm is over.

  • coldspot

    Well we did not get squat up here from that “storm”. Sounds like you so calers got it all. Well I’m glad for you folks you’ve been dry for so long. Sounds like a cold but not very wet weekend coming up. Light snow down to 2500 feet for Saturday.

  • Nicholas

    I didn’t take this picture but it is right next to my house here in Whittier and there was a great double rainbow today. I have noticed that you see them a lot in late winter and early spring.

    http://a7.sphotos.ak.fbcdn.net/hphotos-ak-ash4/s720x720/404215_10150670074392254_736742253_11600967_765814103_n.jpg

  • redlands

    Weather Update : Redlands, Ca — Hi 50 – Low 41 for 2/15/12 —- Rain for 2/15/12 — 0.43 — High Rain-Rate of 2.40 — We got hail — Was reported on the News. This amount of rain was one of the most we gotten for this season — Nov-20-2011 got 0.57 Oct-5-2011 0.47 July-31-2011 got 0.33 — today we got 0.43 of rain —– For the month of February we got 0.45 — for the 2011-2012 only 3.38 — still the 2nd driest year !!!!! I noticed the snow fairly low — bout 3,000 on the near-by hills .

    • Dan the Weatherman

      .27″ fell here in Orange with today’s storm, the first measurable rain here since the storms in the 3rd week of January. Didn’t have any hail here, though. The heaviest rain here so far for this season occurred back in early October when just over an inch fell here.

  • Nicholas

    0.60 here in my rain bucket. Not sure how much hail screws with the rain total but it was a good amount of it in the morning and a bit more in the afternoon.

  • alan

    12″ or so of snow, pretty much snowed nonstop from 10am yesterday till 7am this morning, 8″ falling before nightfall yesterday. 60mph+ gusts all day/night. I had “snow dunes” in my driveway that at one area was waist deep, the other end of the driveway was just 2″. Very interesting storm and the power never went out! Low of 21F while snowing, my record for cold with snow is 17F while snowing…my record low high is 24F, yesterdays high was 27F

    We’re at about 40″ snow for the season, we need another 100″ to make our average :D i think we may get another 40″ which would be two decent storms before the end of march, but man we might not even get that….

  • redlands

    When is the next storm coming ???? Hopefully fairly soon

  • PacificStorm

    Next weekend has potential of a pretty good arctic blast… in fact, the 12z ECMWF almost gave me a heart attack lol. http://oi43.tinypic.com/2uhr3bt.jpg

  • Nicholas

    That looks amazing but the devil is in the details and the fact is that the sun angle has changed enough to where any air mass moving this way would be modified.

  • sc100

    Here’s a mid-February update for percent-of-normal precip since July 1 along the North American west coast from Anchorage to San Diego.

    Anchorage 118%
    Valdez 119%
    Juneau 115%
    Seattle 81%
    Portland 86%
    Eureka 73%
    Sacramento 42%
    San Francisco 42%
    Paso Robles 54%
    Santa Barbara 63%
    Los Angeles 54%
    Long Beach 56%
    Oceanside 61%
    San Diego 87%

    As you can see, the San Francisco-Sacramento-Lake Tahoe corridor has been hit the hardest this winter. Most of the rest of California is not doing much better though.

  • Dan the Weatherman

    Something is keeping the eastern Pacific ridge much more persistent than normal this fall and winter season. I know we are in La Nina and that La Nina can lead to below average precipitation overall, but even in most La Nina winters, this ridge gives way or retrogrades for a while to let some storms in from time to time. Anytime the pattern has attempted to change this year, the high has been more than eager to bounce back extremely quickly, not allowing any wet weather pattern to last for any length of time. I am wondering if there is some persistent anomalous convection going on somewhere that is not letting up, such as in the Indian Ocean, besides that of the La Nina pattern that is teleconnecting to the ridge pattern over the eastern Pacific.

  • Nicholas

    Southwest California area forecast discussion
    National Weather Service Los Angeles/Oxnard California
    335 PM PST sun Feb 19 2012

    Looking a bit further out…extended models do not indicate any
    decent chance of significant rainfall through the end of the month.

    • Dan the Weatherman

      This winter is sure starting to remind me of either 2001-02 or 2006-07. I just can’t get over the fact this pattern cannot seem to change!

      • Dan the Weatherman

        Like I said above, something is relentlessly holding this eastern Pacific ridge of death in place this year and not even allowing it to shift for any decent length of time and I am very eager to find out what factor(s) are contributing to this.

    • alan

      Yeah no surprise there no more storms were expected in feb, 10 more days in feb, that’s a normal stretch between storms even in a wet winter.

      Long range GFS has been pretty consistent at giving us a monster cold storm in the 1st week of March, all eyes on that and it’s lookin’ more likely to happen then not. If it comes to fruition that’ll be our crowning glory for the winter :D lol

      • redlands

        alan — where do u access this info —- would be nice to get cold temps and snow in redlands,ca

  • Ken K.

    Models this evening are hinting at some possible rain Monday to Wednesday next week. Hinting at the trough will be further west. We shall see?

    • Ken K.

      Looks dry again. Oh well, guess we will have to wait until the first week of March for Alan’s storm.