textproduct: San Joaquin Valley

KEY MESSAGES

1. Temperatures will remain about 5 to 10 degrees above normal Friday before a relieving cool down this weekend.

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

3. Although low confidence, a 60-70% probability exists for 72 hour snow accumulation greater than 2 inches above 9000 feet from Sunday into Wednesday morning.

DISCUSSION

Today's highs in the San Joaquin Valley were mainly in the upper 90s, and some record high maximum temperatures were still tied. We are anticipating at least slightly lower temperatures on Friday in both the Central Valley and the Mojave Desert in eastern Kern County due to the weakening of the ridge of high pressure that has been giving us the very warm temperatures. The probability for a high of at least 95 degrees is currently at 20-30 percent for Friday.

Much cooler temperatures arrive Saturday with further cooling on Sunday into early next week. We will see well below average temperatures by Sunday, while Saturday will be seasonably warm. Chances for high temperatures below 70 degrees are at 30-40 percent by Sunday with a similar probability on Tuesday. Even better chances for these cooler readings are in store for Monday (65-75 percent). Precipitation chances are about 50 percent for the higher elevations of the Sierra Nevada into the Mojave Desert for Sunday, and the Weather Prediction Center is still showing a marginal risk (5-15 percent chance) for excessive rainfall for Sunday. We are forecasting at least a slight (10-20 percent) chance of thunderstorms for the mountains and desert. Valley and Sierra foothill locations show a slight (15-20%) chance of light showers on Sunday and Monday. The chance of 0.10 inch of precipitation in these areas is 20-30 percent, mainly Sunday afternoon and evening. Snow levels in the Sierra Nevada are about 8,000 feet for Sunday night and about 7,000 feet on Monday night. During both evenings expect some rain mixed with snow near these elevations with precipitation falling mainly as snow above these levels. There is a good chance that many locations above 9,000 feet will see at least a couple of inches of snow from Sunday until Tuesday. Precipitation chances are mainly confined to the higher elevations of the Sierra on Tuesday, or about 20 percent, while lighter amounts are likely. Otherwise, we will remain much cooler and more fall-like for much of next week.

Temperatures moderate Wednesday and rise closer to seasonal averages by next Thursday. Dry conditions will prevail for the latter part of next week.

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

Heat Advisory until 10 PM PDT this evening for CAZ300>322.