National Weather Service - Discussion

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Area Forecast Discussion

National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Sunday, January 29 2023 - 12:43 AM PST

SYNOPSIS... There is a chance of rain in the San Joaquin Valley and light snow in the Sierra Nevada and adjacent foothills this afternoon into Monday. Snow showers are possible over Kern County mountain passes tonight and Monday. Sub-freezing temperatures are conceivable in the San Joaquin Valley each night and early morning from late Monday night until Thursday morning.

DISCUSSION... A trough of low pressure will move southward into Northern California today. A cyclone aloft should develop in the base of this trough tonight as it passes through the service area. The upper-level area of low pressure will pivot eastward Monday. As a result, there is a chance of rain in the San Joaquin Valley and light snow in the Sierra Nevada and adjacent foothills this afternoon into Monday. Rain amounts, in any, in the San Joaquin Valley will be generally less than one tenth of an inch. Snow levels in the Sierra Nevada foothills will start at around 3,000 feet this afternoon, before falling to about 2,000 feet tonight. Snow amounts will be an inch or less from 2,000 feet to 3,000 feet. Snow accumulations will be one to three inches from 3,000 feet to 4,000 feet. Snow amounts will be three to five inches above 4,000 feet.

Snow showers are possible above 2,500 feet along Interstate 5 over Tejon Pass and along Highway 58 over Tehachapi Pass tonight and Monday. The best chance of accumulating snowfall will be from 10 PM PST tonight until 10 AM PST Monday morning. One to two inches of snow is conceivable, which could cause travel delays and/or road closures. If you must travel, allow plenty of time to reach your destination.

A ridge of high pressure will move eastward over the Eastern Pacific Ocean Monday night and Tuesday. This ridge of high pressure should make landfall over the west coast of the United States Tuesday night. The ridge of high pressure should amplify as it progress eastward across the Western United States Wednesday through Thursday. The tail end of a trough of low pressure could clip the northern portion of the forecast area Thursday night into Friday. This is a low probability, low impact scenario. A Freeze Watch is in effect for the San Joaquin Valley each night and early morning from late Monday night into Thursday morning due to the possibility of sub-freezing temperatures. Here are probabilities of minimum temperatures of 32 degrees or lower for locations in the San Joaquin Valley on Tuesday, January 31st, 2023:

Merced - 84% Madera - 79% Hanford - 69% Lemoore - 69% Visalia - 64% Porterville - 64% Reedley - 64% Delano - 59% Fresno - 54%

AVIATION... MVFR visibilities, with local IFR visibilities, are likely in the San Joaquin Valley this morning due to mist. MVFR conditions are possible in and near showers this afternoon and tonight.

AIR QUALITY ISSUES... On Sunday, January 29th, 2023, fireplace/wood stove burning status is: no burning unless registered in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties. Burning discouraged in Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.

CERTAINTY... The level of certainty for days 1 and 2 is medium. 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... Wind Advisory until 4 PM PST this afternoon for CAZ337>339.

Freeze Watch from late Monday night through Thursday morning for CAZ301>303-305>307-309>312-314>316.

Winter Weather Advisory from 3 PM this afternoon to noon PST Monday for CAZ334-335.