BASIC PATTERN:
Large Scale Pattern –
- Last week of Jan: extremely dry for all of California. Warmer than normal conditions continue, with subtropical upper high pressure recurring in California during this final week.
- February: Three rainy periods are suggested for Feb: One around the 1-6, another about the 12-16, and another within about the 24-28 Feb. The rainy periods in Feb appear sufficient to produce near normal monthly totals of rain and snow in the Sierras and mountains of northern California. Southern California appears to remain warmer and drier than normal.
- March: March is colder than normal, but also wet. This suggests mostly minor but frequent frost/freeze events. Colder and wetter than normal in NW California coastal mountains. Colder than normal with seasonable precipitation amounts for N Sierra Nevada. Drier than normal is indicated for central and S California. Somewhat dry in most of California, but with chance for a little above normal precipitation in far N California coastal mountains N Mendocino Co north, and in northern Sierras, and Siskiyou’s. Above normal frost risk in NW California (Mendocino/Sonoma/Napa Co’s and near or above normal frost risk S Sacramento Valley and Central California. March 2022 appears dry in SOCAL.
- January’s rainfall and snowfall were extremely low for a normally robust winter month. At the other extreme, we saw a wildfire in the Big Sur coastal mountains around 21 Jan, and conditions in Northern California and Sierra west slope were becoming conducive for wildfire activity, due to recurrent dry Santa Ana-type winds and almost one month of dry weather.
- Recurrent fronts, some with rains, from the North Pacific will tend to support about normal frost/freeze events for the late winter: Feb and early Mar, including SOCAL citrus and avocado regions. There will be plenty of input of moisture from weakening troughs that landfall into N and Central California. Cold airmasses will tend to be marine type rather than continental arctic, originating in the Yukon.
FORECASTS FOR CALIFORNIA
Precipitation Trend: The main dates of precipitation are: Feb 1-2, 3-6, 12-16, and 24-28.
Forecast for Northern and Central California:
NORCAL Rains: Feb 1-2, 3-6, 12-16, and 24-28.
CENTRAL CALIF Rains: Feb 2, 4-6, 13-16 and 27-28.
WARM SPELLS: Jan 28-31, Feb 9-11 and 19-23.
COLD SPELLS: Feb 1-6, 12-17 and 24-28.
FRONTS WITH RAINS: Feb 1, 3-4, 12, 24 and 28.
FROST AND FREEZE: Feb 7-10 and 17-20.
Forecast for S California:
SOCAL RAINS: Feb 3-5, 14-16 and 28.
SOCAL WARM SPELLS: Jan 28-Feb 1, 8-12, and 19-23.
SOCAL COOL OR COLD SPELLS: Feb 13-16 and 28.
FROST PERIODS: Feb 6, 15-16 and 22-24.
FRONTS WITH RAINS: Feb 4-5, 14, and 28.
Sierra Nevada:
Dates of mountain rains and snows: Feb 2-6, 13-16 and 25-28.
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The listing of dates normally included for hot and cold spells, and precipitation are based on our CFSDaily and CFSDailyAI forecast products, and present expected trends in precipitation and temperature (CFSDailyAI) to 4km. Our system gives some consideration of terrain and coastal influence. We consider the CFSv2 as one of the better ways to represent basic weather down in the sub-monthly time scale beyond the 15 day GFS or monthly maps from CFSv2 or NMME.
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Southern California Deserts Outlook for Jan 28-Feb 28, 2022:
Highlights: The CFSv2 model shows a return to near or a little above normal temperatures for SOCAL in Feb, and warmer/drier than normal for Mar. Best chances for freezes in Feb and Mar are in the dry cool airmasses behind cold fronts, after dry downslope winds diminish or subside. The CFSv2 model is suggesting a trend towards warmer than normal days in Mar. If this occurs, then frosts may become less frequent than normal. We note that NORCAL is colder than normal per CFSv2 in Mar, while SOCAL is warmer than normal per CFSv2 guidance.
Looking Ahead – Long Range Outlook
Mar 1 – Apr 30, 2022 - N and Central California.
Summary – N and Central California: We list here the trends from the North American MultiModel Ensemble (NMME) with regard to an overall statement on the frost season.
NORCAL and Central California: Below normal temperatures for both Feb and Mar 2022. Slightly below normal temperatures for Apr 2022. NMME results for April 2022 show near normal rain in the Delta and Northern California, and near normal temperature for Apr.
Mar 1 – Apr 30, 2022 - For SOCAL mountains westward to coast:
Results from NMME for SOCAL Feb-Apr: Warmer than normal. Drier than normal Feb and Mar, but near normal rainfall for April (a month of usually meager rainfall).
From CFSv2 monthly guidance: Feb will have near normal nighttime lows for S California, San Luis Obispo Co and south, and continued cool with some frosts/freezes. There is support for a continuation in frost/freeze frequency through most of Feb a few dry cold fronts maintaining cold dry airmasses into SOCAL coastal valleys. The frost risk in Feb, and again in early March includes counties of Ventura, interior Orange, Riverside, and interior San Diego as well. The southern deserts have decreased frost risk in latter Feb and Mar.
CFSv2 monthly guidance suggests troughs coming into California and the Sierra Nevada to Great Basin at times during Feb and again in Mar. There is a possible up-tick in rains during latter part of Feb and in Mar for California. Opportunity exists for frost and freeze in the prime cool-season food-crop areas of the southern deserts and western Arizona during non-windy periods. Again, the best chance of frost/freeze will be following dry cold frontal passages and after dry downslope winds subside.
In summary, after the robust storms during Dec, and a possible up-tick of rains a few times in Feb and in early to mid March (NORCAL), it nonetheless appears that we are more likely to have a drier than normal season overall, with some seriously low reservoir levels at the beginning of the long dry hot season in May-June.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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