Area Forecast Discussion

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National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Friday, September 13 2024 - 1:07 PM PDT

KEY MESSAGES...

1. Brief warmup through Saturday before a cooldown begins Sunday and intensifies Monday. Temperatures will remain below average through next Friday.

2. A WInter Weather Advisory has been issued from 11 PM Sunday night through 5 PM Monday afternoon above 8,000 feet from Fresno County to Yosemite NP. There is a 55 percent probability of 3 inches or more of snow at Tioga Pass as snow levels drop to feet on Monday. Overall, there is a 45 to 75 percent probability of 3 inches or more of snow above 8,000 feet.

3. There is a 20 to 50 percent probability of 0.05 inches of rain or more for most of the San Joaquin Valley Monday.

4. Winds will pick up in Eastern Kern County Monday due to the trough and again later in the week. These increases in wind gusts can increases the threat of wildfires despite better humidity recovery.

DISCUSSION...

A weak ridge is developing over our area as the trough that brought cooler temperatures and stronger winds earlier this week moves out. This weak ridging brings warming temperatures with Saturday having a 60 to 95 percent probability of high temepratures of at least 92 degrees to the Valley.

However, a trough is expect to start sliding in bringing some cooling on Sunday before a major drop on Monday. For Monday, there is about a 90 percent probability of high temperatures below 80 degrees for the San Joaquin Valley. In addition to the well below average high temperatures, there is a 15 to 40 percent probability of overnight lows into Tuesday morning being 50 degrees or less in the population centers with higher probabilities of lows below 50 in the rural areas of the San Joaquin Valley.

The major story with this trough is the precipitation. Down in the San Joaquin Valley, we are looking at a 20 to 50 percent probability of 0.05 inches of rain or more for Monday with a 10 percent or less probability of the same amount in Kern County including Bakersfield. In the Sierra Nevada, snow levels are forecast to drop to 7,500 feet on Monday. There is a 45 to 75 percent probability of 3 inches of snow or more for elevations above 8,000 feet around Yosemite including Tioga Pass. However, these snow probabilities decrease beginning in Fresno County down to Tulare where there is a 45 to 50 percent probability of a dusting of snow above 7,500 feet in Kings Canyon and Sequoia National Parks. A Winter Weather Advisory has been issued for elevations about 8,000 feet from Fresno County to Yosemite NP. This Winter Weather Advisory is the earliest in at least 20 years.

This trough also brings in strong winds for the mountains and eastern Kern County. These increase in wind gusts can play a major factor to the ongoing fires. It is not out of the question that a wind product may be issued for Monday for portions of eastern Kern County due to the wind gusts.

Temperatures rebound a bit for Tuesday through Thursday with 35 to 75 percent probabilities of highs of at least 80 degrees through the week. Model ensembles agree a secondary trough will slide in on Wednesday into Thursday but with low probabilities of rain in the Valley and a 40 to 50 percent probability of an inch of snow or more above 9,500 feet Wednesday and Thursday.

AVIATION... Areas of MVFR and local IFR visibilities near wildfires. Otherwise, VFR conditions will prevail across the central CA interior over 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... Winter Weather Advisory above 8000 feet from 11 PM Sunday to 5 PM PDT Monday for CAZ323-326>328.