textproduct: San Joaquin Valley

KEY MESSAGES

1. The heat trend continues with temperatures about 10-15 degrees above average today and for the next several days.

2. Moderate HeatRisk is likely through the Central Valley tomorrow with a 70-80% probability, which rises to 80-90% for Sunday.

3. A Heat Advisory has been issued for much of the Valley for this coming weekend into early next week as temperatures are expected to continue to increase after today.

DISCUSSION

While a high pressure ridge has largely parked itself over California and the Great Basin, a weak moisture influence from a low pressure system off the Pacific Coast has allowed cloudier skies to track over the central portion of the state today. These clouds will remain over the area sporadically into tomorrow afternoon, though ceilings are expected at or above 25,000 feet. Temperatures will remain well above average for this time of year, generally between 10 and 15 degrees above these season normals and moderate to high probabilities for triple- digit highs in the San Joaquin Valley during the weekend. On Saturday, there is a 60 to 70 percent probability, though mostly in the southern and western portions of the valley in Kern and Kings Counties. However, the ridge will strengthen on Sunday, driving probabilities up to 90 to 100 percent for these locations, and near 50 to 60 percent for most other locations of the Central Valley. While cooler daytime highs can be expected in the foothills, the effects from the overnight thermal belt will drive morning lows upwards between 70 and 75 degrees, providing little relief at night without the use of air conditioning.

This prolonged period of above average temperatures looks to continue through much of next week, with a 95 percent probability for temperatures to exceed 95 degrees each afternoon in the San Joaquin Valley through Thursday. A pattern change is possible next Friday as ensemble means show a weak low pressure trough tracking through the region. However, the relative lack of strength and position of the trough will only fell temperatures by a few degrees and will remain above season averages at least through next weekend. In fact, the warm, dry conditions are favorable to continue through the next two weeks, as indicated by the NWS Climate Prediction Center, which gives a 50 to 60 percent probability for above normal temperatures and a 33 to 40 percent probability for below normal precipation.

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 from 11 AM Saturday to 11 PM PDT Tuesday for CAZ300>322.