textproduct: San Joaquin Valley

KEY MESSAGES

1. A low pressure system brings chances fro more widespread precipitation beginning this afternoon. There is a 10 to 20 percent chance for thunderstorms from the eastern San Joaquin Valley to the central Sierra Nevada and adjacent foothills.

2. Wind Advisory for the Mojave Slopes and Desert from 5 PM Saturday through 5 AM Monday.

3. Slight chances for precipitation continue each day over the higher elevations of the Sierra Nevada until Wednesday.

4. Warning trend to end next week.

DISCUSSION

An upper level trough is currently oriented northeast to southwest across northern California, with a localized cutoff low currently spinning off the central California coast. Over the next 12 to 18 hours, the cutoff low will gradually push into central California, resulting in additional chances for precipitation to round the week off. Through 5 PM Sunday, there is a 40 to 50 percent probability for greater than one-quarter inch of rainfall in the eastern San Joaquin Valley. These probabilities increase with higher elevations, up to 80 to 90 percent in the Sierra Nevada from Yosemite NP through the southern Sierra in Tulare County. Probabilities for an inch or more in this area is at 40 to 50 percent. However, with snow levels generally around 7,000 feet today and falling to 5,500 to 6,000 feet tomorrow, much of the precipitation in the mountain areas will be falling as snow. Through 5 AM Sunday, expected snow totals at the higher elevations of the Sierra are between three to six inches.

This system will also bring stronger wind gusts to the region, especially in the Mojave Desert Slopes in the lee side of the Tehachapi Mountain range, beginning this afternoon and lasting through early Monday morning. During this time period, there is a 60 to 70 percent probability for maximum wind gusts to exceed 50 mph and as such, a Wind Advisory has been issued for this area.

Into next week, a series of weak pieces of energy are expected to track through central California, resulting in additional minor chances for precipitation, though mainly confined to the higher elevations of the Sierra Nevada. Snow levels rising to 8,000 feet on Tuesday will keep much of the potential precipitation as rainfall. However, each day through Wednesday has up to a 25 percent probability for measurable precipitation (>0.01 inches).

A high pressure ridge is favored to build in over the region towards the end of the work week, driving temperatures upward. There is a 70 to 80 percent probability for maximum temepratures to exceed 85 degrees across the valley and desert areas by next Saturday.

AVIATION

VFR conditions are expected for the next 24 hours in the San Joaquin Valley. Showers developing across the San Joaquin Valley after 21Z will result in some areas of MVFR conditions, with IFR possible in especially heavy rain showers. -RA to -SHRA will continue through at least 12Z Sunday across the valley and foothill areas.

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 5 PM this afternoon to 5 AM PDT Monday for CAZ337>339.