textproduct: San Joaquin Valley

KEY MESSAGES

1. Extreme Heat will continue to be the major weather concern over the weekend and early next week. Extreme Heat Warnings and Heat Advisories have been extended through the upcoming weekend to account for this.

2. Persistent hot and dry conditions will also continue to promote the potential for wildfires with cured fuels.

3. Potential for thunderstorms over the Sierra Nevada crest increases this afternoon and continues for each afternoon through the weekend, peaking this weekend with chances of 10 to 20%.

DISCUSSION

High pressure ridging remains in control over Central California. For the most part, we will remain hot and dry. Expect hotter temepratures today and this weekend. A 50 to 60 percent chance of a high of at least 105 degrees is shown for the San Joaquin Valley today and increases to 70 to 80 percent by Sunday. In terms of 110 degree readings in the Valley, the best chance would be on Sunday, or at 15 percent or less, except for portions of Kern County, such as Bakersfield, are currently at 40 to 50 percent. As for the Mojave Desert, particularly the Indian Wells Valley, there is a 40 to 50 percent chance of a high reaching at least 110 degrees each day until Monday. As flow remains south to southeast, additional monsoonal moisture will pass into our region through this weekend and bring a threat of Sierra Nevada thunderstorms. There is a 10 to 20 percent chance of afternoon/evening thunderstorms in the Sierra Nevada, mainly in the higher elevations towards the crest, for today until Sunday.

We will see a gradual lowering of temperatures beginning Tuesday and a cooling trend continues into the remainder of next week. Triple digit heat persists, but highs will generally lower to 100 to 103 degrees for Tuesday and Wednesday. More seasonal temperatures prevail by late next week, with the arrival of an upper-level trough passing over Northern CA and the Pacific NW. Afternoon highs largely in the 90s in the warmest locations of our forecast area. However, we will see an uptick in Sierra thunderstorms Wednesday and the remainder of the week.

FIRE WEATHER

Low minimum humidity will continue this weekend into Monday of next week, with the Mojave Desert seeing 7 to 12 percent each day while the San Joaquin Valley and Sierra Nevada foothills remain in the teens. Overnight humidity recoveries will be moderate to good overall. Thunderstorm chances will occur mainly along the Sierra Nevada crest, or 10 to 20 percent today through Sunday and again by the middle of next week. A 5 to 10 percent chance of isolated dry thunderstorms also exists for this area each day through this weekend. Any fires that develop will have the potential for large plumes due to mixing heights of 9,000 to 10,000 feet.

AVIATION

VFR conditions will prevail for the next 24 hours with light northwest winds during the day and variable winds overnight.

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

Extreme Heat Warning until 8 PM PDT Sunday for CAZ337>339. Heat Advisory until 8 PM PDT Sunday for CAZ300>317-319-321-332- 334>336.