textproduct: San Joaquin Valley

KEY MESSAGES

1. Extreme Heat will continue to be the major weather concern over the coming 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 tomorrow afternoon and continues for each afternoon through the week, peaking this weekend with chances of 5 to 20%.

DISCUSSION

Temperatures stayed the same or even slightly cooled on Thursday but remained above average. The ridge of high pressure will continue to dominate through the weekend with a warming trend, The Valley will see a leap from a 20 to 50 percent chance on Friday to a 60 to 90 percent chance on Saturday and Sunday of highs of at least 105 degrees. However, Sunday has a 15 percent chance or less of highs reaching 110 in the Valley. In the Desert and Slopes, there is a general 10 to 20 percent chance through the weekend of highs of at least 110. However, the Indian Wells Valley continues to be very hot with a 40 to 60 percent chance Saturday and Sunday of 110. A word of caution, however, as thunderstorm chances increase to 5 to 20 percent across the Sierra Nevada for the weekend due to the ridge moving allowing for monsoon moisture to return.

Monday begins a change albeit a 55 to 85 percent chance of much of the Valley south of Merced of highs of at least 105. By Thursday, the Valley sees a 15 to 45 percent chance of triple digits as the ridge breakdowns and flattens. A trough begins to set itself up off the coast on Thursday leading to cooler temperatures next weekend. The CPC is favoring a pattern change by going from a 33 to 40 percent chance of above average temperatures in the 6-10 day outlook to near normal in the 8-14 day outlook. The CPC also has a 33 to 50 percent chance of above average precipitation along the Sierra Nevada and in parts of Eastern Kern County due to monsoon moisture moving in.

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.