BASIC PATTERN:
Large Scale Pattern –
- The westerlies continue are farther south now, but the onshore-moving systems are tending to be weaker than normal. Despite some moist airmasses coming east-northeastward from the Pacific and subtropical areas, there will continue significant interruptions to the wetter pattern during Dec. We expect recurrence of a cool and wet pattern in early to mid Dec for N and Central California, and another wet period around the December holiday period.
- We note that the sea surface temperature anomalies from the NOAA/NESDIS Coral Reef Watch Program is showing redevelopment of limited El Nino conditions focusing near the Mexico coast, i.e. east of 130W and affecting southern and western Mexico in Dec. If this trend continues, it may result in deep cold troughs at times in California and possible turn to dry conditions with freezes coast of N and Central California in Jan.
- It is dry until about 21st, then rain with higher snow levels Nov 22. Rains appear to resume about 26-30th with some lowering of snow levels in the Sierras about 12-14 Nov then a bit intermittently wet and cold 16th onward. For most of the remainder of Nov, FoxCFSDailyAI continues to show a fairly consistent wet trend in the Sierras from Sierra County south to Mariposa County.
- For Jan 2023, we return to a tendency for below normal precipitation in nearly all of California, Sierras, and drier airmasses than normal coast and SOCAL, and above normal freeze risk (cold temperatures) in central coast and S California. Cold windy conditions with freezes coastal valleys alternate with showery rain episodes. These rain episodes alternate with periods of hard freezes with very dry, breezy cold events with unusually dry airmasses.
- SOCAL precipitation trend for the first period of 30 days: 12/1-5, 12/9-15, 12/20-25.
- In Feb 2023, from NMME and CFSv2 models, there is a tendency for us to return to mostly below normal precipitation, except for possibly some rains and Sierra snows during 12-19 Feb, and 27 Feb – 2 Mar.
- March 2023 looks currently (from NMME Model) colder than normal, and near to below normal precipitation (showery rains and snows for the Sierras, but dry and windy at the coast).
FORECASTS FOR CALIFORNIA
Forecast for Northern and Central California:
Norcal RAINS: 12/1-5, 12/9-15, 12/23-26, 12/29-1/1/2023.
Norcal WARM SPELLS: Dec 7-8 and 18-21.
Norcal COOL SPELLS: Nov 29-Dec 5, 9-16, 23-26 and 29-Jan 1.
Norcal FROSTS: Dec 5-9, 15-20, 26-29 and Jan 2-4.
Central Calif RAIN: Dec 1-5, 10-15, 23-26, 29-Jan 1.
Central Calif WARM SPELLS: Dec 8-9 and 18-21.
Central Calif COOL SPELLS: Dec 1-6, 10-16, 23-27 and 29-Jan 1.
Central Calif FROSTS: Dec 5-8, 16-19, 27-29 and Jan 2-3.
Forecast for Southern California:
SOCAL RAINS: 12/2-5, 12/9-15, 12/23-26, 31.
SOCAL WARM SPELLS: Dec 7-9, 18-21 and 28-29.
SOCAL COOL OR COLD SPELLS: Dec 1-5, 9-16, 23-27 and 31-Jan 2.
SOCAL FROST: Dec 6-8, 16-17, 27-28 and Jan 1-2.
Forecast for Central Sierra Nevada:
Central Sierra Nevada Precipitation: Dates of rain: Dec 1-6, 11-15, 23-27 and 30-Jan 2.
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The listings of dates normally included for hot and cold spells, and precipitation are very approximate. They are based on our CFSDaily and CFSDailyAI products; and present expected trends in precipitation and temperature (CFSDailyAI) to 4km. Our system gives some consideration to 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 December 1 - January 1, 2023
Highlights: In 1-5 Dec, and possibly several wet cold fronts between 23 and 31 Dec, we see a chance for resumption of a more normal development of occasional cold fronts frosts, and upper lows with showers and rains in the SOCAL Deserts.
Looking Ahead – Long Range Outlook - January 1 - February 15, 2023
NORCAL and Central California coastal valleys, and Central Valley: In the graphical version of this forecast, the CFSv2 model solutions are posted for your review. In general, NMME has been appearing a little drier than the CFSv2 for California as a whole. Near to above normal temperatures will alternate with cold frontal passages and cold events. There is a chance for intermittent wet periods during the first 15 days of Dec, and again for 18th through the Dec holidays. Near normal precipitation in Jan 2023 from the CFSv2 (wetter than normal in Siskiyou Mountains and Cascades in California, with plenty of snow), but a little drier than normal per the NMME, in west portions of N and Central California.
For SOCAL mountains westward to coast: January 2023 currently appears seasonably cold with above normal risk of frost and freeze. Rainfall in the eastern deserts may actually go above normal in Jan 2023, while snowfall amounts in mountains are near or a little above normal. Although cutoff lows may develop on occasion to bring rains to Southern California, the supply of water will be heavily dependent on strategic planning of water storage in Northern California and Sierras with the expected rains in NORCAL, and snows in Sierras and Siskiyou’s.. We greatly appreciate the snowpack. It is a valuable resource to use wisely. We expect to return to abnormally dry conditions in SOCAL and at the central coast in mid-Jan onward, and Feb, with recurrent frosts/freezes. The NMME Model at this time shows a dry and cold March for California. Notwithstanding, the challenge is to intelligently use whatever snow water equivalent (SWE) we have. The season for Atmospheric Rivers to beneficially add to lakes and rivers is Dec-Feb. We have seen good rains and snowpack in Nov from a couple of storms. If December also includes low snow levels in the Sierras, then that could help us as we struggle with a dry spring to maintain normal monthly precipitation water equivalent. The dry and unusually cold (frost-freeze events) in Feb and Mar for Central California will impact the challenge for water storage in all of California, including SOCAL from this winter’s rain season.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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