California’s very dry winter to continue through the first half of Jaunary

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One of the defining characteristics of California’s Mediterranean climate are its well-defined wet and dry seasons–corresponding to meteorological winter and summer, respectively. One can almost always expect a bone-dry summer outside of occasional summer thunderstorms in the higher mountains, and increasingly heavy winter rains and mountain snows beginning some time during the late fall or very early winter.

The observed weather in 2011, however, didn’t follow these time-honored expectations. The rainy season in Northern California lasted until early July, and fresh snow on the ground greeted July 4th revelers in the Sierra Nevada. The wet season seemed to be getting off to a respectable start, with a fairly strong system bringing significant rain and wind in mid-October. After a few more minor precipitation events in early November, though, the proverbial spigot shut off abruptly in Northern California. In Southern California, an unusual series of “outside slider”-type systems brought some significant (and in some cases anomalously heavy) rainfall to coastal areas through November. By the beginning of December, however, even the outside sliders tapered off, and December 2011 turned out to be one of the driest Decembers on record for almost the entire state. In fact, most of the state (with the singular exception of the far northwestern corner) received essentially no precipiation at all–and what little did fall was hydrologically insignificant.

(National Weather Service/NOAA)

The question, of course, is how long this present very prolonged dry spell will continue. The answer, in short, is that it will last at least another 1-2 weeks. There are not, at present, any compelling indications of a major longwave pattern shift in the near future. In fact, it appears that the persistent East Pacific ridge will strengthen in the coming days, bringing balmy conditions to much of California with continued dry and stable weather. The MJO–which in most winters is a fairly significant indicator of impending westerly jet incursions–appears to be rather unimportant this year in forcing pattern changes (which is not extremely surprising given prevailing La Nina conditions).

Day 12 GFS, 500 mb heights

(NCEP)

The only interesting feature in the extended forecast models at the moment is some early indication of a potential retrogression of the ultra-persistent block over the Pacific. If this actually does occur, it could shift the mean trough axis towards the West Coast, though because flow would be highly meridional and northerly over California conditions could become dramatically colder and unsettled but ultimately result in little precipitation due to the cold continental origins of the source airmass. In any case, this possible development is still far in the future–and extremely dry patterns such as the present one are notoriously persistent. For now, we can only hope that the pattern in early 2012 becomes more promising than the one that closed out 2011…

© 2011 WEATHER WEST

130 thoughts on “California’s very dry winter to continue through the first half of Jaunary”

  1. A cold 17 degrees this am would be nice to see the snow start falling. Sac NOAA says snow levels for No cal next week at 3000 to 3500. I’m right at 2900′ but the lee side of the Marble Mountains always drops the level lower for me with increased precip amounts. I hope the models due follow up for next week.

  2. Well looks like socal should have at least one shot @ real precip between the 21st & 25th, been rather consistent with the on-slot of systems, at least from point conception north…. wow i just realized i’m talking 10 to 15 days out still…..ah well, we shall see….

  8. It looks as if the long awaited pattern change will begin next week as rain prospects increase for Norcal (with much needed snowfall in the Sierras) and Socal getting into the act by next weekend and the following week as storms start to move in from the Gulf of Alaska. A cutoff low may bring some light rain in Socal this Sunday and may linger into early Monday as a second system drops in as an inside slider keeping the marine layer moisture deeper west of the mountains. The weather is certainly beginning to look much more interesting than it has for about the last month in Socal and for about the last month and a half for Norcal.

  10. This in particular has been an encouraging sign the last several days. Things are looking good. From NWS Sac this morning:

    ONE THING THAT HAS BEEN VERY CONSISTENT OVER THE PAST SEVERAL DAYS IS THE MODELING OF A LONG PRECIPITABLE WATER PLUME PROGGED TO EXTEND TO THE COAST BY THE END OF THE WEEK. PW VALUES WITH THIS PLUME REMAINS PROGGED AT NEARLY AN INCH AND A HALF SO SOME OF THE SHORTWAVES MOVING THROUGH NORCAL WILL HAVE A GOOD MOISTURE TAP AND COULD BE FAIRLY GOOD PRECIP PRODUCERS.

  11. 70% chance now, but wait a sec. Weather Channel says “no rain” (!) wha- ?, but NWS says “yes rain”. We’ll know by this time tomorrow, but my guess is weather channel is using the GFS which has a dry scenario.

  12. Weather and Weatherstar (local weather channel forecast on cable local on 8) says just sprinkles tomorrow with the 18z GFS and NAM showing the moisture mostly just hugging the upper elevations. IT should be interesting to see what takes place if anything.

    Also with such dry air in place anything think we could have some microburst of the rain gets heavy enough?

  13. Warm and breezy tonight a first in A long time. Probably will struggle to get below freezing tonight. 20 percent chance of snow showers tomorrow. Tuesday things start to ramp up here with strong winds and lots of precip per NOAA Medford Or. Oh yeah go 49ers!!!

  16. interesting turn tonight. NWS S.D. forecast 90% chance of showers Sunday Evening here(S.D. Valleys), with saturation from the surface to 700MB for San Diego County, less to the north. With a better chance for all of So. Cal Next Saturday. Time will tell.

  18. We did feel a couple drops after mass this morning, but with the the ceiling still (Im guesstimating) 5 to 6K, that tells me no rain yet, but NWS is still going with 70% now for to night.

  19. Over here in Whittier it looks more like a monsoon event with a low sun angle and a much lower temp. High and mid level clouds with dark basses but only a few drops hitting the ground.

  20. Wow we actually had a few light snow flurries in the last hour. What a change from the last two months. Yesterday splitting wood in a T shirt and today bundled up in insulated coveralls and sweatshirt and still cold. Sounds like very heavy rain coming our way starting weds with storm force winds on the coast.

    • Do you live close to the Oregon border? I know some places up there average over 100 inches of rain a year. Do you live in one of those areas? I’m always fascinated by the microclimates that exist here in this part of the country.

      • Up here in the Butte county foothills… SW facing slopes here make for great orographics. The average here used to be 110″… looks like these upcoming systems will have great orographics so this location could pick up several inches per storm (right now I’m expecting 2 – 3″ from the first storm Wed/Thu… 4 – 6″ from the second Fri-Sun storm… and it looks like it could also snow come Sunday as the cold air behind the low moves overhead).

        • Yeah, some of the rain your area gets can be unreal. I like looking at rainfall totals from there when big storms come in and be amazed at the totals. How close do you live to Strawberry Valley? That’s pretty well known down here on local newstations as an area that gets a ton of rain. Also, I have an uncle who lives in Berry Creek, which I think is in your general direction.

          • Strawberry Valley is around 30 miles to my southeast… the city I’m in is Magalia… right above Paradise. And yep Berry Creek is maybe 15 miles to my south. Will post rainfall totals from Wed – Sun either later Sunday or Monday… may have to dump the gauge a few times it looks like.

      • Yep about 20 miles south of the border in Siskiyou county. Actually in the Scott Valley outside of Fort Jones up against the lee side of the Marble Mountains. Yes, we do have a very different microcline from the rest of the valley. Usually 2 to 3 times the amount of snow or rain from the rest of the valley. Rain averages around 25 inches per year.

  22. Well – Redlands, Ca at my station wont go dry for the month of January — We have 0.02 of rain as of 842pm — Got a long way to go to catch up — hope more is to come — Anyone else get any rain

  24. we are picking up showers over the last couple of hours here at the house9Granite Hills),activity is picking up now. Looking good for next weekend, 1st heavy rain event for us in the southland as the system moves south. nice to see the rain falling.

  27. NOLF at IB didn’t report anything, but there’s about an 8th of an inch in the can this morning. Brown Field up on Otay Mesa got a little more .14

  28. Got down to 11 this am and still is only at 31 degrees. Winter storm watch in effect per Medford NOAA for most of their fca for Tuesday thru ?. Sounds like this pattern could last a while.

  30. Only .04″ fell here in Orange yesterday with this last storm. I’m certainly looking forward to bigger storms and hopefully the ones forecast this weekend materialize.

  31. Models keep trending with less rain for So Cal. More rain for No Cal. I guess they need it more but things are looking a bit grim again for So Cal.

  32. Looks like a potentially record-setting hard freeze for much of the Sacramento Valley tonight. That sort of snuck up by surprise–temps are already in the mid 20s and plummeting with dewpoints 5 to 15 F. Much of the Bay Area is already below freezing this evening, and there are more snow showers along the far north coast. Major and potentially record-setting sea-level snow event for Washington and perhaps parts of Oregon, including Seattle where over a foot may fall. Unfortunately…just cold temps for most of CA out of this one. The good news is that rain is definitely on the way for the entire state…I will try to get a late-night update out tonight. Stay tuned!

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