textproduct: San Joaquin Valley

KEY MESSAGES

1. A brief warmup will occur Tuesday with dry conditions across the region.

2. Another low pressure system approaches the area on Wednesday, bringing wind and lower temperatures.

3. An elevated fire weather risk takes place over the mountains on Friday and Saturday due to increased northeasterly winds and lowering humidity.

4. A warming trend occurs this weekend into early next week with continued dry conditions.

DISCUSSION

A mainly dry pattern will occur for the next several days, except for a slight chance of light precipitation over the Sierra Nevada on Wednesday afternoon until Thursday morning. High temperatures will recover a bit on Tuesday, but will remain near seasonal averages, while cooler overnight lows occur. The chances for dense fog in the Central Valley are generally low, or around 15-20 percent. However, there is moderate to high confidence of fog/mist developing by early Tuesday morning as well as Wednesday morning.

The next low pressure system will bring cooler than average temperatures for Wednesday and Thursday with increased winds across the region. There is a slight chance of light precipitation during this period, but amounts will once again be minimal with a 15-25 percent chance of a tenth of an inch or greater over the Sierra. The upper low moves into the Great Basin, but cuts off and retrogrades towards Southern California by the weekend. In terms of winds, the best chances for 40 mph or stronger gusts will be over the Sierra Nevada crest, coastal ranges, and the Kern County mountains and desert, including along the Mojave Desert slopes. Models continue to show northeasterly flow aloft for Friday and Saturday over these areas. While this is typical of a Mono wind pattern, the guidance suggests a weak to moderate event at this time with the highest chances (60-70 percent) for gusts above 40 mph confined to the highest elevations of the Sierra Nevada during Friday into Friday night. As for the Kern County mountains and desert, the chances for gusts this strong are 50-60 percent at the highest, or Saturday afternoon and evening, although lower chances are shown for Friday afternoon and evening (at 25-35 percent). As the flow will be easterly, this will be favorable for some downsloping and lowering humidity, so elevated fire weather concerns will exist by Friday and Saturday.

The upper-level low will move over Baja California by Sunday and high pressure ridging will gradually build over the Golden State. This will provide a warming trend for Sunday until early next week. Latest CPC outlooks continue to show odds tilted towards above average temperatures and below average precipitation through the middle of this month.

AVIATION

VFR conditions prevailing until 11Z Tuesday. Moderate to high confidence for MVFR conditions in the valley from 11-16Z Tuesday with a 60-70% change for visibility below 5 statute miles and a 20-40% chance for the Tehachapi Valley. VFR conditions expected in the mountains and desert for the next 24 hours.

AIR QUALITY ISSUES

None.

CERTAINTY

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

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

None.