textproduct: San Joaquin Valley

KEY MESSAGES

1. Slight chance for thunderstorms across the Sierra Nevada Friday, increasing chances on Saturday.

2. Above average temperatures across the CWA on Friday and Saturday.

3. A closed-low enters the area over the weekend to early next week with the best probability for weather impacts Sunday through Tuesday.

DISCUSSION

A high pressure ridge will gradually build over central California on Friday, leading to a warming trend across the region that will last through Saturday. In the western San Joaquin Valley, there is a 60 to 70 percent probability for maximum temepratures to exceed 90 degrees on Friday, with probabilities at 20 to 30 percent in the eastern Valley; these probabilities increase to 70 to 80 percent for the south valley on Saturday but remain at 20 to 30 percent for the north valley. The warming temperatures lifting through the Sierra Nevada will bring a slight chance for thunderstorms along the crests Friday and Saturday afternoon, with chances at 10 to 15 percent from Yosemite NP to Sequoia and Kings Canyon National Parks.

Late Saturday into Sunday, a cutoff low pressure system is expected to slide south along the Pacific coast which will bring the next round of precipitation to central California, beginning in the central Sierra Nevada and spreading southward into Monday. As of now, there is a 30 to 40 percent probability for more than one-tenth of an inch of precipitation along the central Sierra crest between Saturday and Sunday, though these probabilities increase to 40 to 50 percent between Sunday and Monday. Snow levels during this time are projected to be between 7,000 and 8,000 feet, resulting in moderate chances (50 to 60 percent) for at least a trace of snow above these levels. Additional chances are possible on Monday and Tuesday as the low remains relatively stationary off the central California coast before pushing eastward into Wednesday. Additionally, there is a 15 to 20 percent chance for thunderstorms across the Sierra Nevada Sunday through Tuesday, with some minor chances (5 to 10 percent) for the San Joaquin Valley on Tuesday.

Through the middle of next week, another high pressure ridge is expected to build over California and the Great Basin, once again pushing temperatures into the upper 80s across the valley and desert areas.

AVIATION

VFR conditions will prevail for the next 24 hours over Central California.

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

None.