Area Forecast Discussion

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National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Tuesday, January 21 2025 - 4:45 PM PST

Update to Air Quality Issues Section...

KEY MESSAGES... 1. Dry weather will continue through Friday with above average high temperatures and below average low temperatures across the San Joaquin Valley.

2. Widespread sub-freezing temperatures are forecast across the rural areas of the San Joaquin Valley tonight. A Freeze Warning is in effect.

3. Light rain for the San Joaquin Valley and Sierra Nevada snow possible this weekend.

DISCUSSION...

Freezing temperatures will continue tomorrow morning as the ridge of high pressure continues to remain over the area. There is a 35 to 65 percent chance of freezing temperatures for much of the Valley except for the rural areas of Fresno and Bakersfield which is at 25 percent chance or less. Overnight low temperatures increase on Thursday as probabilities decrease to 30 percent chance or less of freezing Thursday morning. Fog remains a possibility but at a 20 to 30 percent chance tonight into Wednesday morning.

Latest ensembles agree that a trough will slide south from Canada beginning Friday into Saturday which will retrograde to be over California Saturday into Sunday. This new trough brings a 10 to 35 percent chance of a tenth of an inch or more of rain in the Valley. However, this trough will be cold as snow levels are forecast to drop to 3,500 to 4,000 feet by Sunday morning. This does not bode well as there is a 45 to 55 percent chance of an inch or more of snow for the Kern County mountain communities including Pine Mountain Club and Tehachapi.

The ensembles diverge on Monday into next Tuesday as to the low's movement and position whether it will stay over Southern California or if it will move east. However, the probabilities have a 25 to 65 percent chance of freezing overnight temperatures returning Sunday through Tuesday morning. Looking ahead, the CPC 6-10 day outlook has a 50 to 70 percent chance of below average temperatures with a 33 to 50 percent chance of below average precipitation. The 8-14 day outlook continues favoring dry conditions with a 33 to 40 percent chance of below average precipitation but with equal chances of above and below average temperatures.

AVIATION... 18Z/0Z Update

VFR Conditions will prevail through 6Z. Between 6Z and 12Z, MVFR to IFR conditions spread over the San Joaquin Valley. There is a 20 to 30 percent chance of LIFR due to fog in the San Joaquin Valley between 12 and 18Z. Otherwise, VFR conditions will prevail for the rest of Central California.

AIR QUALITY ISSUES... On Wednesday January 22 2025, Unhealthy for Sensitive Groups in Fresno and Kern Counties. Fireplace/Wood Stove Burning Status is: No Burning For All in Fresno and Kern Counties. No Burning Unless Registered in 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 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... Freeze Warning until 9 AM PST Wednesday for CAZ301>303-305-306- 309>313-315-316.