textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. Warm conditions are expected through the weekend with temperatures across the area running 5-10 degrees above seasonal averages.

2. A pattern change remains likely by early next week with temperatures cooling quickly to well below average for this time of year, along with a chance of rainfall throughout the area (low to moderate confidence).

DISCUSSION

Another warm day is in store for the lower elevations on Saturday as we remain under a ridge of high pressure, including highs near 90 degrees in the San Joaquin Valley. Today's highs reached 90 degrees in some valley locations. Chances for maximum temperatures of 90 degrees or warmer on Saturday are at 55 to 65 percent for the Central Valley. Winds have generally decreased in the mountains and desert, while humidity has been improving in the mountain areas this evening. Thus, the Red Flag Warning and Wind Advisory were allowed to expire at 10 PM PDT this evening. Although, some increased easterly winds will continue through the overnight hours with gusts near 30 mph at times. Winds will further decrease on Saturday as pressure gradients relax as the upper-level low moves inland towards the Colorado River Valley.

For Sunday, above average temperatures continue, but with a minor decrease. Current probabilities for highs at or above 90 degrees in the San Joaquin Valley will be considerably lower than on Saturday, or at 15 to 25 percent. The ridge of high pressure weakens and gives way to an upper-level shortwave trough. This feature will eventually bring more noticeable cooling by Monday. Even more cooling and chances of precipitation enter the forecast for Tuesday and Wednesday. For the San Joaquin Valley we are looking at a 20 to 30 percent chance of rain with even better chances into Wednesday. There is at least moderate confidence that we will see a much cooler pattern, as highs struggle to exceed the lower 70s in the Valley for the latter part of next week. As of this writing, chances of a 70 degree reading or lower are at 50 to 60 percent for Wednesday until next Friday. Precipitation amounts of 0.10 inch ending Wednesday afternoon are at 35 to 45 percent for the San Joaquin Valley and of 0.50 inch or greater for the Sierra Nevada are at a similar percentage. As for the frozen precipitation, snow levels are at 8,000 feet on Tuesday and Wednesday with amounts of several inches.

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

None.