textproduct: San Joaquin Valley

KEY MESSAGES

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

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

3. Dry conditions to prevail through the week and will produce elevated fire weather concerns late this week into early next week.

DISCUSSION

Today was another seasonably warm day across much of the region, with highs in the San Joaquin Valley in the upper 90s. Maximum temperatures in the desert were once again into the triple digits, or as hot as 107 degrees at China Lake NAF. Tuesday will be yet another similar day across the region with dry conditions persisting, courtesy of a dry southwest flow over our forecast area and a broad ridge of high pressure centered over the Rockies and High Plains.

The ridge will gradually retrograde as we head into midweek while strengthening. Highs will be a touch warmer on Wednesday and rising further on Thursday and the end of the week. Humidity will also lower a bit each day as the week progresses.

Temperatures in the San Joaquin Valley from Friday until next Monday will have a moderate to high chance to reach at least 105 degrees, including a 30-40 percent chance north of Fresno County and 70-80 percent from Fresno County southward on Friday. Although, the probabilities over the weekend into next Monday rise to 45-55 percent for locations north of Fresno County. Overall, we will see at least a few very hot days with Moderate to Major HeatRisk developing. As for the Kern County desert, highs will rise to 110-115 degrees for this period, with a 85-95 percent chance of a high of at least 110 degrees. We are also looking at very warm overnight lows in quite a few locations, including the desert, as well as the larger metropolitan areas in the SJ Valley.

AVIATION

VFR conditions will prevail for the next 24 hours.

FIRE WEATHER

Hotter temperatures will arrive late this week and produce elevated fire weather conditions. Minimum humidity will lower to 5 to 10 percent in the Kern County desert Thursday until early next week with values of 10-20 percent in most other locations. Overnight humidity recovery will be poor to moderate at best. Winds will generally be diurnal and terrain-driven, although the typical prone locations such as the Mojave Desert slopes and coastal ranges will see gusts 25-30 mph at times, mainly afternoons and evenings. Gusts near the lakes will reach near 25 mph. If any wildfires or grass fires develop, they will have the potential to intensify and spread rapidly.

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

None.