textproduct: San Joaquin Valley

DISCUSSION

A ridge of high pressure remains in place today and will remain in place for the next several days. Temperatures will therefore be well above average for the forseeable future, with high temperatures about 10-15 degrees above the average for this time of year. A moderate heat risk will likely remain in place throughout the Valley today with a 50-65% chance in the northern Valley and a 75-90% chance in the southern Valley. There is a possibility temperatures will reach above 95 degrees through much of the Valley today (45-60%). The heat will build even further after today, hence we have issued a Heat Advisory from tomorrow through Tuesday of next week given the prolonged and sustained heat in place. Temperatures could potentially reach over 100 degrees by Sunday which looks to be the hottest day of this forecast, with a 35-50% chance through most of the Valley, excluding localized areas in the southern Valley where chances are much higher. Overnight low temperatures in the Valley will likely be in the mid-60 to low-70s in this timeframe, providing at least a little relief from the intense daytime heat. A widespread moderate heat risk will remain in place therefore for the next several days, with the potential for a major heat risk in the southern Valley (60-75% chance) this weekend through at least early next. A moderate heat risk poses a risk to the most vulnerable populations and people who are not properly hydrated. Remain in an air-conditioned building whenever possible and drink plenty of water.

In the long range temperature outlook, it is likely to be slightly cooler, but slightly is emphasized as it will still be well above average for this time of year by late week next week. The probability of temperautres reaching above 95 degrees on Friday of next week is about 45-60% across the Valley, a significant reduction from the near 100% probabilities of this weekend into early next week. The Climate Prediction Center (CPC) 6-10 day and 8-14 day temperature outlooks have us in a 90-100% chance and 70-80% chance of above average temperatures respectivally. In addtion, the CPC has us seeing average precipitation for this time of year in the 6-10 day outlook, but has a 33-40% chance we will see below average precipitation in the 8-14 day outlook.

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 10 PM PDT Sunday for CAZ300>322.