textproduct: San Joaquin Valley

KEY MESSAGES

1. Extreme Heat Warning continues for the Mojave Desert and Indian Wells Valley through this evening. Major HeatRisk expected with afternoon highs 102 to 110 degrees.

2. High pressure over the region will maintain temperatures near season averages for the remainder of Central California on Tuesday.

3. Warming trend begins Wednesday with Major Heat Risk by Friday for the Mojave Slopes and Desert and by the weekend in the San Joaquin Valley.

4. Dry conditions to prevail through the week.

DISCUSSION

Extreme heat continues for the Mojave Desert, as does another day of above normal temperatures for the San Joaquin Valley. Latest National Blend of Models (NBM) guidance indicates low probability (10-20%) for valley triple digits south of Merced, with higher probability (50-75%) along Interstate 5 between Lost Hills and Kettleman City. Across the Mojave Desert, probability for max temperatures exceeding 105 are still running high (60-80%) between Edwards AFB and China Lake, especially in areas below 3000 feet elevation. Thus, the Extreme Heat Warning for the eastern Kern County desert will remain in effect until 9PM this evening.

Looking ahead, the large ridge of high pressure causing extreme heat slides eastward, allowing a slight cooldown on Tuesday, until gradually sliding back westward and eventually over California by this weekend. By Friday, NBM indicates 60-80% probability for valley-wide high temperatures above 105, particularly south of Merced. There exists likewise high probability for high temperatures above 110 across the Mojave Desert. Combined with low temperatures in the 70s for the valley and 80s for the desert, the Weather Prediction Center places 50-80% probability for Major Heat Risk across the forecast area this weekend and the start of next work week.

Along with this warmup, region-wide relative humidity will correspondingly drop. Latest forecast indicates minimum relative humidity as low as 5% in the Mojave Desert and 15% in the San Joaquin Valley on Friday and the weekend. Though wind will remain diurnal and terrain-driven, the combined hot and dry conditions will be favorable for fire growth and spread given seasonably dry and cured fuels. Fire weather products may be issued if even more aggressive conditions are expected.

Both the 6-10 and 8-14 day Temperature Outlook courtesy of the Climate Prediction Center place our area likely to remain above normal, with 60-70% probability covering much of California as of their latest outlooks.

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 9 PM PDT this evening for CAZ337- 339.