BASIC PATTERN:
Large Scale Pattern -
- Overall, the longwave pattern continues mostly dry and hot. Some showers and TSTMS are indicated about 10-14 August.
- The number of days over 100 degrees in Fallbrook, Escondido, and interior San Diego County will tend above normal in Aug due to recurrent upper high pressure.
- Precipitation Trend Aug 3-31. Precipitation Dates for N and Central California: Scattered thunderstorm (TSTM) about 10-12 Aug. Dry lightning risk Aug 2-4 and Aug 9-12, then again in early to mid Sep. The sea surface temperature anomaly maps have continued to show a robust El Nino pattern along the Peru-Ecuador coast and along the equator westward to 160W. The warm SSTA pattern normally associated with El Nino is expected to continue expanding west toward the Dateline during Aug and Sep.
- Precipitation trends in S and W Mexico Aug 3-31: Tropical cyclone-type rains: Hot and scattered TSTMS during Aug in NW Mexico.
- Precipitation In California for Aug 3-31,the Sierras have near normal rainfall from Tahoe south through the central Sierras in Aug per latest CFSv2 guidance.
- However, for precipitation in the longer range, Sept..near normal rain amounts. Oct.. hot and very dry through California and our state's mountain areas.
- In the fall, we transition from a mostly dry autumn (October 2023) to a wetter trend in late Nov for NORCAL and N-central California, followed by a wet, typical El Nino type of Dec 2023. This is in response to an increasing El Nino pattern, this late Nov and Dec.
FORECASTS FOR CALIFORNIA
Forecast for Northern and Central California:
NORCAL Precipitation Trend: Aug 8-12 (NE areas)
NORCAL WARM/HOT SPELLS: Aug 4-8, 14-20, 23-28,Sep 1-5
NORCAL COOL SPELLS: Aug 9-12, 21-22 and 30-31
Forecast for Central California
Central Calif Precipitation: Dry across the region
Central Calif WARM/HOT SPELLS: Aug 4-9, 14-21, 24-29,Sep 1-6
Central Calif COOL SPELLS: Aug 10-12, 22-23 and 30-31
Forecast for S California
SOCAL RAINS: Aug 8-12 shwr E,Aug 30-Sep 3.
SOCAL WARM TO HOT SPELLS: Aug 3-9,13-22,24-30, Sep 1-6
SOCAL COOL SPELLS: Aug 11-12, 23,31
Forecast for Central Sierra Nevada:
Central Sierra Nevada Precipitation - Main dates of TSTMS are... Aug 8-11, Aug 31-Sep 4
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The listings of dates normally included for hot and cold spells, and precipitation are approximate. They are based on our CFSDaily and CFSDailyAI products; and present expected trends in precipitation and temperature (FoxCFSDailyAI) to 5km. Our system gives some consideration to terrain and coastal influence. We consider the CFSv2 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 Aug 3-31, 2023:
Highlights: Below normal rainfall from monsoonal influences in most areas but near normal rainfall (showers) through the Sierras. Tropical cyclone influences remain mostly south in Baja up to mid Aug, but may increase around the end of Aug.
Looking Ahead – Longer Range Outlook Sep 1-30, 2023
Western Mexico - including most of Baja California: near normal rainfall for the period approximately late Aug through Sep.
S California Coast through mountains: Near normal temperatures, with near normal rainfall, consisting of mountain thunderstorms (TSTMS).
S California Deserts through central and east San Bernardino Co: Seasonably hot with near normal rainfall consisting of desert TSTMS N and Central California- Sep 1-30. High pressure and hot weather will tend to alternate with troughing, minimally showery conditions in the Sierras in Sep and cooler, dry and breezy conditions. A good descriptive expression to aid fire readiness over Sep 1-30: ìhot-dry-breezyî with some hot NE-E wind events possible.
(Terms and Definitions Used In This Weather Outlook)
Figures: Alan Fox
Text: Zane Stephens, Alan Fox, Fox Weather, LLC,
Copyright © 2023 Fox Weather, LLC. Used by permission.