textproduct: San Joaquin Valley

KEY MESSAGES

1. Rain is spreading south across the Valley tonight with heavy snow in the Sierra Nevada. Scattered thunderstorms are possible Sunday afternoon.

2. Winter Storm Warning remains in effect through 11 PM Sunday for the Sierra Nevada above 7,000 feet.

3. Wind Advisory for Mojave Slopes through Sunday night.

DISCUSSION

The upper low continues to spin off the coast of Northern California late this evening. A cold front and associated band of showers with embedded thunderstorms are working south across central California. The showers and storms are reaching the Fresno and Hanford areas. Locally heavy rainfall is occurring with some of these cells. This poses a low risk for the burn scars, especially the French which has been experiencing rain for the past several hours and is most sensitive. Rates so far have been around a tenth of an inch per hour or less, however, so at the moment holding off on any flood hazards. The rain will continue progressing south overnight, likely reaching Bakersfield around 3 AM PDT. Heavy snow in the Sierras will continue overnight with rates exceeding 3 inches per hour at times. The upper low will slowly propagate eastward Sunday to northern CA. The steadiest rain will end early in the morning. Additional scattered showers and storms will develop in the afternoon within the cyclonic flow of the upper low. Somewhat steep mid level lapse rates around 7 C/km and a moist boundary layer should allow 200-400 J/kg of CAPE to develop during peak heating. This activity and moist upslope flow will continue the snow in the Sierras into the evening before tapering off as the upper low weakens and shears apart later today.

Troughing will remain in place until late Tuesday when it ejects east to the Rockies and Plains. Temperatures will continue running a bit below normal until that time. Another trough will pass through the Pacific Northwest and portions of northern California late week. Most of the impacts should remain north of the area. Temperatures will continue to warm late week with highs returning to the mid 70s to lower 80s. Confidence in the extended is considered high given the quieter pattern.

AVIATION

VFR conditions expected for the most part through the period. MVFR conditions are possible at times in the heavier showers overnight. Scattered showers are expected through the day with thunderstorm chances increasing this afternoon. Maintained the PROB30 for TS for all TAF sites, except BFL.

AIR QUALITY ISSUES

None.

CERTAINTY

The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is high.

Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES

Wind Advisory until 11 PM PDT Sunday for CAZ338. Winter Storm Warning until 11 PM PDT Sunday for CAZ323-326>328- 330-331.