Area Forecast Discussion

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National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Saturday, April 26 2025 - 4:20 AM PDT

UPDATE... Updated AVIATION section.

KEY MESSAGES...

1. Windy conditions are expected across the Mojave Desert this weekend with a High Wind Warning for the Mojave Slopes.

2. Temperatures will be much cooler than climatological average this weekend then trending warmer next week.

2. Winter-like weather today as valley rain and mountain snow will be observed.

3. A slight chance (15%) for thunderstorms today, mainly during the afternoon and early evening.

DISCUSSION... Change in the weather is now being ushered-in as a Pacific Storm approaches the West Coast. Ahead of the storm on Saturday, clouds and winds are starting in increase as temperatures continue their cooling trend. Satellite water vapor imagery is showing the storm taking shape and starting its drop toward Central California. High-Res short-range ensembles still placing Central California in the target zone as a the cold-core upper low traverses the area on Saturday.

Ensemble analysis still leaning toward widespread precipitation becoming likely across most of the San Joaquin Valley. Mountain locations still have a better chance of measurable amounts. Current PoE of measurable precipitation sits at 30%-40% from Merced County toward Yosemite NP on Friday night and 30%-50% on Saturday with near 60-70% for the higher elevations near Yosemite. Therefore, while confidence on mountain precipitation is growing, valley rain still has high uncertainty south of Fresno County. Thunderstorms will be a threat this weekend over much of the area as probabilities still trending higher over the last few days. This threat includes the San Joaquin Valley, foothills and Sierra Nevada. Storm moves out around Sunday with ridging, drying and warming dominating the period from Monday through at least next Thursday.

As for the winds, ensemble surface wind analysis shows an increase in gusts over the Mojave Desert as speeds reaching into the upper 30-40 mph range. Saturday looks more promising with PoE of 55 mph plus winds sitting between 50%-65%. Will upgrade the advisory to a high wind warning as the Mojave Slopes favor high wind criteria. By Sunday, a return to a ridge pattern will decrease winds for the remainder of the period.

As the storm exits later in the weekend, temperature begin a rebound and rise to the mid 80s by Tuesday. The PoE of mid 80s jumps up to a range of 40%-60% at that time. As a note, PoE of 90 degrees sits at 30%-40% by next Wednesday. Thursday shows slightly high probabilities and implies continue warming into the latter part of next week.

AVIATION...12Z Update:

In the San Joaquin Valley and West Side Hills, local MVFR in low clouds thru 18Z Sat. Areas of MVFR and local IFR in low clouds, showers and thunderstorms between 18Z Sat and 12Z Sun.

Across the Sierra Nevada, widespread mountain obscuring IFR in low clouds, rain and snow between through 12Z Sun.

Across the Kern County portion of the Mojave Desert, VFR will prevail thru 12Z Sun with wind gusts greater than 50 kts along the Mojave Desert Slopes.

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... Wind Advisory until 11 AM PDT Sunday for CAZ337-339. High Wind Warning until 5 AM PDT Sunday for CAZ338. Winter Weather Advisory until 11 AM PDT Sunday for CAZ323- 325>330. Winter Weather Advisory until 11 AM PDT Sunday for CAZ331- 333>336.