30-Day Weather Outlook for October 18, 2024, to November 18, 2024

Oct 16, 2024

BASIC PATTERN:

Large Scale Pattern

The focus of upper troughs shifts to the Pacific Northwest then Great Basin, then dives SSE into Arizona while trying to settle on a predominant pattern.
For forestry and mid-Fall Fire Season 2024 in NORCAL and Sierras. Bottom line is: recurring very warm and breezy periods with rapid shifts to cold and sparsely showery, with snow in the mountain areas (Sierras, Rockies, and even into N Arizona. Precipitation consists of mostly small amounts for SOCAL and Arizona rain amounts, then rapidly shifts to heavier showers as fronts gain strength briefly.
Central California appears to continue with general below normal rain amounts, but stay tuned for some changes and rapid pattern shifts, which are currently not obvious from the CFSv2 monthly forecasts for Nov and Dec.
After mid Dec, we head into a period of above normal rainfall (and mountain snows). This is welcome newsÖif it actually happens as predicted.
Southcentral and S California appear to have below average rainfall late Oct (20-31) and in early Nov. There is a normally occurring seasonal pattern shift that occurs in mid Nov, and this could end up being a nice ëwake-up-callí: winter is coming, and we could actually see one or two wet months during early to mid winter - late Dec - Jan-early Feb.
Other than some showers for Central and S California in mid to late Nov, predicted rain amounts appear to continue well below average through most of Dec. The main rains of winter are currently not expected to develop until the Dec holiday period, and Jan 2025.

Forecast for Northern California
NORCAL Precipitation: Oct 17, 22-23, 25, 27, Nov 9-14 and 17-19,
NORCAL Warm/Dry Periods: Oct 20-21, 28-30, Nov 3-7 and 15-16.
NORCAL Cold or Frost Periods: Oct 17, 22-27, Nov 9-14 and 17-20.
North Sierra Precipitation: Oct 18-19, 22-24, 27, Nov 10-14 and 18-19
Central Sierra Precipitation: Oct 18-20, 23-25, Nov 12-14 and 19.

Forecast for Central California
CENTRAL CALIFORNIA Precipitation: Oct 19-20, 23-25, Nov 12-14 and 18-19.
CENTRAL CALIFORNIA WARM DRY PERIODS: Oct 21-22, 27-31, Nov 2-8 and 16-17.
Central California Cold Periods: Oct 19-20, 23-26, Nov 11-15 and 18-20.

Forecast for Southern California
SOCAL SUMMARY: Significant change from our forecast issued last week. It gets cold with gusty winds, and periods of showers, with snow in the Mountains on 18-19, 22-25, followed by a possible Santa Ana and rapid,
windy warmup period at the end of Oct. More showers are possible in ?? Nov, but with the main period of rains occurring in mid Nov.
SOCAL PRECIPITATION: Oct 20-22, 27-31, Nov 4-9, 15-17 and 20-22
SOCAL WARM PERIODS: Temecula-Riverside-Escondido foothills near 90 in Santa Ana periods (briefly).Overall, temperatures remain above average.
SOCAL MILD or Cold PERIODS: Oct 19, 23-24, Nov 1-2, 11-13 and 18.

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The listings of dates normally included for hot and cold spells, and precipitation are approximate. They are based on GFS and our CFSDaily and CFSDailyAI products; and present expected trends in precipitation and temperature (FoxCFSDailyAI) to 5km. Our AI system gives some consideration to terrain and coastal influence. Although we consider the CFSv2 one of the better ways to represent basic weather in the sub-monthly time scale, performance of the CFSDaily. CFSv2 daily products during storm seasons has been especially inconsistent and difficult to apply to the useful criterion needed by cropland agriculture, and viticulture beyond the 15ñday GFS.

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Southern California Deserts Outlook
Above average temperatures, and below average rainfall for the period. However, it appears that there are some cold and showery/rainy events in S and Central California mountains/Sierras and in the state of Arizona.

Looking Farther Ahead
Precipitation is below average for Nov and Dec. Mid Nov turns briefly above average for precipitation in NORCAL and north-central Sierras for a few days. Dec returns to subnormal rainfall in NORCAL from Bay Area north. Heavy rains and mountain snows in the ORWA region (Oregon, Washington), mainly coast and Cascades, due to atmospheric Rivers in Jan-Feb. Some of the above average rainfall reaches into NORCAL and Central California in Jan 2025, but then dry and warmer weather returns Feb 2025.

(Terms and Definitions Used In This Weather Outlook)