Recent rain welcome, but not nearly enough: more dry weather on tap

Filed in Uncategorized by on November 24, 2013 41 Comments

Recent Weather Summary

The weather system that affected the entire state of California last week ended up being somewhat more impressive than initially anticipated. Despite the overall lack of strong dynamic forcing, some cold air aloft and a locally sharp frontal boundary ended up producing some heavy convective precipitation over a fairly wide swath of Northern California. Later in the week, the same low pressure area brought scattered thunderstorms to Southern California which even resulted in a couple of highly-localized instances of flash flooding. Almost the entire state received a decent soaking rain from this system, though the spatial distribution of precipitation was not what might typically be associated with a late-November system: the southern deserts received almost as much as the San Francisco Bay Area!

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Locally very strong offshore winds developed in the wake of the departing low across a large portion of Northern California, resulting in some serious wind damage in a few locations and actually fanning a number of new wildfires in Napa, Lake, and Mendocino counties. Despite the significant rainfall experienced only 24-48 hours earlier, Red Flag Warnings were issued for parts of the Bay Area and several thousand acres eventually burned. Having Red Flag conditions–let alone multi-thousand acre fires–is pretty extraordinary in the Bay Area this time of year, let alone immediately following a soaking rain event. This fire activity is a testament to the effect the incredible dryness of calendar year 2013–coupled with the longer-term dry period spanning multiple water years–is having on the regional environment.


Did recent rainfall make a dent in the long-running deficit?

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So, the big questions remains: did this week’s precipitation help to alleviate California’s enormous water deficit? Well, in a word: no. While any precipitation is certainly better than no precipitation, this is normally a rather wet time of year across most of the state. This week’s precipitation event was very locally heavy but generally a light-to-moderate event at best. 



The entire state remains well behind average precipitation, even for the month of November. Calendar year 2013 remains on track to be the driest on record for California, with some regions in Central California set to exceed previous records by a very wide margin. The most recent Drought Monitor update depicts a large expansion of “extreme drought” conditions in California, which now cover more than a quarter of the state.


The medium term outlook: more of the same.

The million dollar question right now is when this extremely persistent dry spell will come to a more meaningful end than merely a day or two of modest precipitation. The answer: not within the foreseeable future. While for a while it appeared that a new system could drop some substantial precipitation over much of California around Thanksgiving, this system is now expected to drop southward well offshore and weaken with most or all precipitation missing the state to the west and south. Rain may come tantalizingly close to the coastline later this week, but the majority will fall into the Pacific Ocean and not into our major hydrological basins. Southern California stands the best chance at seeing some light showers out of this, but it will almost certainly bring lighter precipitation than the last system.



In the longer range, there are some vague signs of a slight shift in the longwave pattern as the mean East Pacific ridge retrogrades ever-so-slightly to the west and (perhaps) weakens slightly. This still isn’t a very favorable pattern for significant California precipitation, but it may at least open the door for a marginally more active pattern. One thing to keep an eye on for early December is the possibility of an Arctic outbreak over the Western U.S. Recent runs of the GFS and ECMWF have been depicting a high-amplitude high-latitude blocking pattern with very cold air pooling downstream over western Canada and spilling out into the Pacific Northwest and Northern Rockies. While California is probably too far south and west to receive any really cold air in this sort of pattern, the extended model ensembles suggest the possibility of further retrogression such that some cold air could eventually invade from the north and east. This is still a very dry pattern, but it’s certainly more interesting than what we’ve had as of late. Stay tuned!

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  • redlands

    Would be nice to get some real cold temps — along with some snow

  • Dan the Weatherman

    Like I have said before, our main winter storm track in which low pressure systems come from the Gulf of Alaska southeastward over water into CA has really been blocked over the last couple of years. Many of our storms have been forced up and over the NE Pacific ridge (that refuses to break down) into western Canada down into CA, bringing more in the way of cold air and less moisture due to an over land trajectory and to make matters worse, also a lack of subtropical moisture from the SW. With this last storm, we did manage to finally have a subtropical connection for a change.

  • Charlie Hohn

    Hi! I’m poster ‘Inyo’ from before. Not sure I like the new comment system… not that I care if you all know my ‘real’ name but I think it is creepy how websites are forcing everyone to share personal info to comment. Same as the Google Plus-Youtube thing, soon there will be no way to separate out your Internet accounts. Ick.

    Anyhow, yeah, while cold blasts are interesting, I’m not sure if it’s a good thing to see in California. The seem to coincide with very dry years. Meanwhile, Vermont has had a very vigorous cold blast – it was 4 degrees this morning! We’ve also got a couple inches of snow, though it seems like the approaching Nor’Easter, which comes at least in part from the storm that rained on CA and the deserts recently, is going to be a mix of rain, snow, sleet, etc.

    Edit: Hmm, it looks like I didn’t *have* to link my accounts and just wasn’t able to figure it out. Oh well. I’ll probably keep this one just out of laziness.

    • I’m not super thrilled about the real name/total integration aspect of it, either, but this new system is (by far!) the best one around in terms of functionality. If you want to, it’s pretty easy to keep the existing account but change the display name and privacy settings…

      • Dan the Weatherman

        One thing that I really like about Disqus is that you can edit a comment after it is posted. It seemed like when I posted a long comment here before, I either left something out or didn’t phrase something the way I really wanted, and I couldn’t go back and change it.

        • Charlie Hohn

          Well, sometimes I just don’t like certain types of change… but I am in general resistant to the merging of every single thing on the Internet (Google and YouTube, every comment thread on the Internet, etc)… I know they say it keeps people honest so they don’t act nasty in one place and not in another, but you know, I don’t act nasty on the Internet anyway (at least not anymore… I used to like to get into dumb arguments, but it’s pointless). I just think it is weird and kind of overbearing. And, everyone likes to curate our content for us without our control. I don’t want the ‘newest content’ or what Facebook thinks are ‘top stories’, I want the comments in the order they were posted. But, on the plus side, now you all get to see a silly image of me pretending to be a bear so I guess there is that.
          OK, Internet Rant over. I have to remind myself I am complaining about posting on a free message board. And if it’s easier for Daniel to use, that’s a big plus.

          Anyway, back to weather. I excitedly checked the models this morning to see if there were any updates on when this cold rain would turn back to snow in Vermont, and I was very sad to see that cutoff low no longer forecast to hit SoCal. Then I saw this in the LA forecast discussion: ” WELL THE GREAT THANKSGIVING RAIN SCARE OF 2013 IS OFFICIALLY DONE. ” I really hope they were being sarcastic.

          • Dan the Weatherman

            I hope they were just being sarcastic in that case. We desperately need rain and it is very hard to get meaningful rain down here in a -PDO, +AMO, ENSO neutral regime like we are in right now, so we need to cash in on every opportunity for rain in a season like this.

    • Dan the Weatherman

      I set up a Disqus account a while back using the same handle (Dan the Weatherman) and the only information I had to provide was an email address, password, username and a handle (screen name). Since I used the same email address for my Weather West account and for Disqus, I didn’t have to provide any additional information to merge the accounts together. I am glad that people aren’t forced to use their real names here. However, I don’t think I would like the idea of not being able to keep your internet accounts separate, especially if you want to blog about different topics.

      I agree with you about cold outbreaks in CA in that they often are associated with dry winters. Last winter and 2006-07 are prime examples of this.

  • snow755

    354 AM PST Mon Nov 25 2013

    By Sunday afternoon/evening, a
    storm over the Pacific NW will enhance N to NE winds across NorCal
    and is forecast to drop southward into our region early next week.
    Have increased probability for precipitation on Monday & Tuesday
    as the storm tracks southward over our CWA. JBB

    that topic above sure wont fit will if it rains come next Monday or tusday

    make that Thursday wish I will give us are 1st ch of rain

    then followed by cold air

    then other storm comeing right on his heels and it looks like a other one after that this on starts after next Thursday not this Thursday

    I have been noted this from the start of the 06z 12z 18z 00z and now the 06z from today

    • There is definitely a trend towards a highly amplified pattern that could bring cold to very cold weather and probably at least some precipitation out beyond day 7. We’ll close out November extraordinarily dry, but perhaps December is looking a little more promising. Current solutions suggest the potential for a pretty significant snow event for the Seattle area.

  • Nicholas Gumina

    Cold brothers unite! We need several big time cold snaps this year in the golden state.

  • Nicholas Gumina

    Looks like the Euro has gone the way of the GFS and showing a lot less rain for the next system.

    • Dan the Weatherman

      I cannot believe that the forecast for my area for Thursday night went from rain, heavy at times to no rain at all in a matter of 2 days. This is absolutely infuriating, despite this being a cutoff low and the fact that I know that cutoffs can do this to us! We desperately need every storm we can get.

      • Nicholas Gumina

        Same here. The most annoying thing is that there is a strong tropical tap of moisture to the south. In an average or an above average year I am sure that moisture tap would have got caught up in the system.

        • Severe Wx

          So far this whole Fall has been a disappointment…and as Daniel implied the clock is ticking…

  • Significant rainfall next week still looks pretty questionable as well. Still looks cold, but there may be very little moisture around. That puts us into December…

    • Still looks like a very cold pattern next week, but only scattered light precipitation looks likely right now (albeit with snow levels likely under 2000 feet). Current GFS/ECMWF ensembles suggest little rain for the first two weeks in December, although there are indications that the MJO may become more active next week, which could help to initiate a pattern change eventually.

  • Nicholas Gumina

    I would like to say have a happy thanksgiving to everyone on Weather West !

  • redlands

    Yes Happy Turkey Day !!!

  • Dan the Weatherman

    Happy Thanksgiving, everyone!

  • snow755

    today 06z is wetter for next weeks low snow event looks like the 12z gfs is following it still needs more hrs

  • Flunking_retirement

    How nice.

  • redlands

    How low is the snow level gonna be ?? I read 3-4000 — Hopefully it will go lower. Did everyone enjoy their Thanksgiving Meal

  • David Thomas


    438 AM PST Fri Nov 29 2013

    it somewhere over the Pacific Northwest by late Tuesday. ECMWF
    a wetter solution at this time while GFS keeps precip quite light.
    GEM is the odd model out this cycle producing an inside slider
    scenario and taking the low to the east of the cwa for a dry
    solution over NORCAL. Wetter solutions have dominated over the
    last couple of days so going at least climo on POP chances seems

    sac is moveing a way from the gfs and going with the wetter ecw with this storm wish is good

  • Nicholas Gumina

    I just saw something that I didn’t think could take place. I saw a large rainbow this morning looking almost dew north. As soon as I went to get a picture of it it went away. I thought you could only see them looking East or West.

  • Newest 12Z ECMWF shows some impressively cold conditions for next weekend across the entire western half of North America, including California. Will have an update within a day or two once it becomes clearer whether any of this will be associated with precip/very low snow levels…

  • Nicholas Gumina

    What is disturbing is the GFS has trended slightly warmer. We need this to be as cold as can be. What I would like to see is a second blast of cold air once the first one moves through.

  • Dan the Weatherman

    It actually rained this morning here in Orange, enough to create puddles in my patio. It was certainly nice to see some rain, especially considering that the NWS had reduced the chances to almost zero over the last few days. There was a chance of sprinkles or possibly an isolated shower, but the rain was heavier and more widespread than forecast. There may be a couple more showers today and I will post a total when the rain ends.

  • Flunking_retirement

    Well, it kinda rained today. Sprinkled 3 or 4 times now. Got to add upto something. I will NOT be joining the mall madess today.

    -Tom in San Diego

  • redlands

    Redlands, Ca Weather Update for November-29-2013 We received 0.03 of rain — guess its better than nothing

    • Dan the Weatherman

      .18″ fell here in Orange today, mostly earlier this morning.

  • Some more administrative news: expect some big changes in the site interface at some point during the next two weeks. Don’t worry–the content will remain unchanged (and all the old stuff will still be there, hopefully even more accessible). Site downtime should be minimal to nonexistent during this process, though it might take a few days to work out the kinks in the new interface once it’s up and running. If you have feedback, just let me know here in the comments section–there’s a good chance it’ll be integrated into the new site layout.

    In the meantime, I’ll have a new post either late today or tomorrow regarding the highly uncertain (but almost certainly very cold!) impending pattern change.

    • snow755

      man highs in OR and WA will only make it two the lower 30s for highs with snow levels down too sea level in all areas

    • Will wait until tomorrow to post, since model solutions are still remarkably divergent. Cold weather is extremely likely this week, and there’s a chance of very cold conditions across most of California. Precipitation currently looks very light, though that could change somewhat if the flow pattern has marginally more over-water trajectory and the potential instability of the very cold air aloft is realized in the form of convective showers. Very low snow levels are possible at some point this week, though again precipitation is expected to be very light or even nonexistent in many areas. Hopefully there is better agreement by tomorrow…

  • snow755

    am starting to noted that the the 12z from sat the 18z from sat the 00z from sat the 06z from today are showing a pattern at chages at 204hrs too wet weather come the week of the 10th so some in two watch has we get closer but I would not get my hops up has the last few times it showed this it drop it at the last sac so we this need too see how this gos this time around

    • snow755

      12z gfs still showing the pattern chages come 204hrs it all so been showing a vary wet storm come thusday of the following week and lasting in two the weekend with other low droping S but am not jumping the gune on this yet has the gfs could drop this at the last sac so its a wait and see game right now on how this will go

      • snow755

        the 12z was a vary good run it has two vary wet storms and then rain or showers the rest of the time this all starts the week of the 10th

  • snow755

    we will have too watch this set up vary close has if this comes in at the right time with all the cold air still trap in the foothills and valley we could be looking at vary low snow levels at the start of the storm be for the winds mixs things out with are storm the folllowing week so some in too watch

  • 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…

  • how effective would cloud seeding be for this season of the year? It’s still manageable for the crops right?