textproduct: San Joaquin Valley

KEY MESSAGES

1. Major Heat Risk for the Indian Wells Valley, Mojave Slopes and Desert with an Extreme Heat Warning in effect through Monday.

2. Prolonged heat is expected to affect the SJ valley and adjacent foothills with a Heat Advisory in effect through Monday.

3. Drier conditions will develop with the warming temperatures, leading to increased fire weather concerns for most of the week.

DISCUSSION

The high pressure ridge over much of the Southwest will continue to cause above normal temperatures for the Valley and Mojave Desert through the next week. Highs in the Valley are likely to stay between 104 and 107 through the weekend, while the Desert will continue to see highs in the 108 to 111 range. Nighttime lows will continue to be elevated, as well, with urban areas in the Valley seeing lows in the low to mid 70's and the desert seeing lows in the high 70's to low 80's. These factors combined will create Major Heat Risk for much of the region with some areas of Extreme Heat Risk, both of which effect much of the population, especially for those without proper cooling overnight.

Along with this heat, relative humidities in the mountains and Valley will be in the teens while the desert will be in single digits, which continues to cause elevated fire risk throughout the region over the next 7 days. Though, due to the consistent ridge, winds will be on the low side.

Looking to the long term forecast, a slight decrease in temperatures may be in store for the region as an area of troughing may move through the west coast by early next week. This is reflected in the current probabilities for triple digits during that time as they slowly decrease from Sunday into Tuesday of next week. Further model runs in the coming days will give more confidence as to if this cooldown will occur.

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

Extreme Heat Warning until 8 PM PDT Wednesday for CAZ337>339. Heat Advisory until 8 PM PDT Wednesday for CAZ301>317-319-321- 332-334>336.