BASIC PATTERN:
Large Scale Pattern –
- The current dry pattern for California is stable. Sea surface temperature related influences (IVTinit™) are consistent in focusing the rain developments mainly west of N and Central California.
- Precipitation trend: Mar 3-4 (NCAL), 9-11 Mar(NCAL-Sierras), 13-14, 22, 25, and 27 Mar. These are generally small events, with snow showers in the Sierras. NW California coastal ranges and Siskiyou’s.
- March: Near normal temperatures in N California, and a turn to warmer than normal in S California. Mar is currently forecasted wetter than normal in coastal Oregon, near or slightly above normal in NW California, and drier than normal in Bay Area south through Monterey Co. Input of moisture from clouds or showers into Central and SOCAL agricultural areas will be spotty/questionable at times through mid-Mar, with higher chance for rains in late Mar.
- Below normal sea surface temperatures are suggested by the latest guidance from the North American Multi-Model Ensemble (NMME) for the period Mar – May 2022. This will tend to support risk of frost near the normal end of frost season in Mar and Apr in N and Central California coastal valleys, including Mendocino and Sonoma Co’s, Salinas Valley, and San Luis Obispo Co coastal valleys.
- Medium-range forecast models performed poorly during this extremely dry late winter period. The stationary IVTinit pattern (related to sea surface temperature anomalies, has kept troughing in the central North Pacific, and high pressure close enough to the California coast to block storms from arriving, or else cause persistent weakness in approaching systems.
FORECASTS FOR CALIFORNIA
Precipitation Trend: The main dates of precipitation are: Mar 3-4, 9-11 Mar(NCAL-Sierras), 14-17 Mar, and 22-23, 25, 27 Mar.
Forecast for Northern and Central California:
NORCAL Rains: Mar 3-4, 9-11, 14-17, and 22-23, 25, 27
CENTRAL CALIF Rains: Mar 3 and 9 (light rain N areas), 15-17, 23
WARM SPELLS: Mar 1-2, 12-13, 20-21 and 27-29
COLD SPELLS: Mar 8-11, 14-18 and 22-24
FRONTS WITH RAINS: Mar 8, 14 and 22
FROST AND FREEZE: Mar 7, 12-13, 17-18, and 24
Forecast for S California:
SOCAL RAINS: Mar 10 (light rain N areas), 15-17 and 23-24
SOCAL WARM SPELLS: Mar 2-3, 12-14, 27-29
SOCAL COOL OR COLD SPELLS: Mar 10-11, 15-17, and 18-20
FROST PERIODS: Mar 5-8, 18-20
FRONTS WITH RAINS: Mar 10, 15 and 23
Sierra Nevada:
Dates of mountain rains and snows are: Mar 9-11, 15-17 and 22-23
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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 March 3-28, 2022
Highlights: After the current cold trend associated with cold frontal passages and airmasses from NW Canada, the CFSv2 model shows a return to near or a little above normal temperatures for SE California deserts, but no clear trend in precipitation for SOCAL deserts in March. Best chances for freezes in Mar are in the dry cool airmasses behind cold fronts, after dry downslope winds diminish or subside. The CFSv2 model is suggesting a slow 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 29 – May 15, 2022... N and Central California: NORCAL and Central California: Near or a little below normal temperatures for Mar 2022. Slightly above normal temperatures for Apr 2022. Near normal rainfall in the Delta and Northern California. Above normal temperatures are possible by mid-May with some highs in mid-90s for a few days possible around 15th.
For SOCAL Mar 29 – May 15, 2022 mountains westward to coast: Progressive trend towards above normal temperature for Apr. Above normal temperature for late Apr to mid-May. Drier than normal in Mar, but near normal rainfall for April (a month of usually meager rainfall). There is potential to turn hot and dry in mid-May, with foothill and coastal valley highs (avocado areas) peaking to u90s.
Additional Comments:
CFSv2 monthly guidance suggests troughs coming through California and Sierra Nevada to Great Basin at times in Mar, although we are emerging from frost season. Again, the best chance of frost/freeze will be following dry cold frontal passages and after dry, downslope winds subside.
The CFSv2 suggests a possible early exit from frost season. However, the dry airmasses and N flow regimes continue at least some residual risk of frost into early spring. With the NMME climate model showing colder than normal sea surface near the California coast in Mar and Apr, there continues some risk of frost at least in central and N California coastal valleys in Mar and Apr.
In summary, despite the possible uptick of rains in late March, a drier than normal rainy season, overall, is likely, with some seriously low reservoir levels at the beginning of the long dry hot season. Watch for some 100+ hot spells early in the summer season for May and June while cool fogs hug the immediate coast/beach.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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