Large Scale Summary
- The longwave pattern has changed to support troughing near the California coast. The storms are primarily warm ones with tendency for Atmospheric River
(AR) conditions to develop. Troughing and focus of rains focus near 25-40N 150W-130W. The zone of heaviest rains at 25N/150W to 38N/133W occurs at
21-22 Dec. - For Central and Southern California, the trend is towards more precipitation. From the (12/15th) Fox Weather LLCís AI application: CANVAZ_B maps for Dec 21-Jan 10: Wet periods, are: Dec 22 Central Calif, Dec 26-27 moderate rains southcentral to southern California. On Dec 29 Atmospheric River AR (heavy rain) conditions occur Mendocino Co coast north to Oregon border. Heaviest rains are 2 inches per day for coast to coastal hills Mendocino/Humboldt Coís to Oregon border on 29 Dec. Storm on 29 brings widespread rains to S California on 30th thence into Arizona. A dry break occurs 1-8 Jan, followed by more widespread rain for SOCAL and Central California. Other rains occur 9 Jan Central California and Central coast to most of S California on 10 Jan, according to the FoxCFSDailyAI_CANVAZ_B model.
Near Term Forecast
NORCAL
- PRECIPITATION DATES: Dec 15-20,22,26, 27-28.
- COLD/FREEZES/WINDS: Dec 25
- MILD/DRY PERIODS: Dec 31-Jan 1. Jan 3-8
- MOUNTAIN SNOWS: Dec 21-22, 26, 27-28.
CENTRAL CALIFORNIA
- PRECIPITATION DATES: Dec 20, 22,26, 27, 28-29 rains. Dry 1-8 Jan, rain 9-10.
- COLD/FREEZES/WINDS: Dec 25, 26
- MILD/DRY: Jan 1-9
- Central Sierra SNOWS: Dec 22-23, 26-27
SOUTHERN CALIFORNIA
- PRECIPITATION DATES: Dec 23,26, Jan 10-11.
- COLD/FREEZES DRY WINDS: Dec 26-28
- WARM/DRY PERIODS: Dec 31 Jan 1-6, 3-6 (possible Santa Ana winds)
- MOUNTAIN SNOWS: Dec 26, Jan 10-12.
SOUTHERN CALIFORNIA DESERTS
- PRECIPITATION DATES Dec 26
- COLD, WINDS: Dec 25
- MOUNTAIN SNOW: Dec 25-26
Medium Term Outlook: Jan 10-31 2026.
NORCAL
- PRECIPITATION DATES: Jan 10-11, 13-16
- MOUNTAIN SNOWS: Jan 10-11, 13-16
CENTRAL CALIFORNIA
- PRECIPITATION DATES: Jan 10-11, 14-15
- MOUNTAIN SNOWS: Jan 10-11, 14-15.
SOUTHERN CALIFORNIA
- PRECIPITATION DATES: Jan 10, 14-15
- MOUNTAIN SNOWS: Jan 10, 14-15
- SOUTHERN CALIFORNIA DESERTS
- PRECIPITATION DATES: Jan 10, 15
- MOUNTAIN SNOWS: Jan 10, 15
Figures and Text: Alan Fox, Fox Weather, LLC
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