Area Forecast Discussion

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National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Saturday, 10 October 2026 - 12:15 PM PDT

KEY MESSAGES...

1. Temperatures drop drastically today into early next week.

2. High wind gusts over 35 mph are likely into Sunday night (65-80% chance) over the San Luis Reservoir with a Lake Wind Advisory issued.

3. There is a marginal risk for excessive rainfall in the Mojave Desert and along southern portions of the Sierra Nevada mountains this coming Sunday.

4. There is around a 50-70% chance for 72 hour snowfall greater than 2 inches above 9000 feet from Sunday into Wednesday morning.

DISCUSSION... A reprieve from the summer-like weather of the past week has arrived in the form of a low pressure system moving in from the Northwest Pacific, while precipitation from the remnants of TC Rachel are expected to move in early tomorrow morning for the Mojave Desert and Southern Sierra Nevada crest. As the remmants moves further north, that precipitation will also shift north and begin to fall over much of the Sierra north of Kern County.

With the chances for this precipitation, there is a marginal risk (at least 5%) for excessive rainfall in the Mojave Desert and into the Tehachapi Mountains tomorrow as much of the rainfall moves into the Southern California and the Desert Southwest. There is also a Slight Risk (at least 15%) in a small portion of southeastern Kern COunty, east of Edwards Air Force Base. The current forecast for rainfall in that area over the whole event is around a quarter of an inch, but there is a 10% chance for an inch or more. There is also a 10% chance for the Sierra Nevada to see an inch and a half or more, but the expected total is a third of an inch to a half inch. Due to the shielding of the mountain ranges on all sides, the San Joaquin Valley is not likely to see much rainfall, aside from the southeastern portions if some showers make over said mountains.

This system will also cause increased wind gusts across the region, in particular for the Mojave Desert Slopes Sunday afternoon through Monday morning and for the San Luis Reservoir through Sunday night. Both of these locations have/will have advisories in effect due to these wind gusts, but breezier winds are expected across the Valley and Sierra Nevada, especially on the leeward side as the winds downslope to the east. These winds will also be coming onshore from the southwest, meaning crosswinds across HW 58 are likely.

As the low pressure system moves further eastwards and the tropical remmants is pushed out towards the Desert Southwest, much cool temperatures and lower snow levels are expected for Monday. These lowered snow levels will lead to the potential for snowfall along the Sierra Nevada crest above 6000 feet as more precipitation is expected for the mountainous regions of our CWA. The expected snowfall amounts are around 3 to 5 inches at the higher elevations, with 1 to 2 inches above 6000 to 7000 feet. This would mainly cause some winter impacts with small pockets of minor impacts at the highest elevations of the Sierra Nevada on Monday.

Looking out after this system into later this week, temperatures are expected to slowly increase once again through next weekend, due to the building of a ridge in the eastern Pacific, meaning highs are likely to rise above normal once again, though triple digits are not likely to return. Highs may then remain steady into early next week. The Climate Prediction Center also sees this rise in temperatures as the outlooks for both the 6 to 10 and 8 to 14 time frames are under likely above normal for the time of year, with normal for the Valley at that time being in the upper 70's. These time periods are also under the leaning below normal for precipitation, suggesting drier weather is possible late next week into the week after.

AVIATION... VFR conditions will prevail 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... Wind Advisory from 2 PM Sunday to 8 AM PDT Monday for CAZ337>339. Lake Wind Advisory until 11 PM PDT Sunday for CAZ300.