textproduct: San Joaquin Valley

KEY MESSAGES

1. Another round of monsoonal moisture will bring chances for thunderstorms across the Sierra Nevada crest through the middle of the week.

2. High pressure over the region will maintain temperatures near season averages for most of this week.

3. Major HeatRisk expected for portions of the Mojave Desert in the latter portion of this week.

DISCUSSION

The high pressure ridge continues to remain stationary throughout this week, leading to consistently above normal temperatures for the Valley and the Desert. The current southerly flow will also continue to bring monsoonal moisture into the region through the midweek, allowing for thunderstorms to develop over the Sierra Nevada crest. Tuesday has the strongest chances for said development at 25-45% mainly from the crest eastwards over the leeward side of the range. These chances also come with a 30-50% chance for a half inch of rainfall above 7000 feet. Thunderstorm probabilities do continue on Wednesday, but they drop to 15-25% that afternoon as the flow over California slowly shifts to coming out of the west rather than the south, which will become even more pronounced by Thursday into the weekend, causing thunderstorm chances to decrease into the 5-15% range.

Looking to the latter half of this week, the Mojave Desert in southeastern Kern County will begin to see more widespread Major Heat Risk due to temperatures in the afternoon nearing 110 and early morning lows in the mid to upper 70's. The days with the highest Heat Risk so far are Thursday through Saturday. This type of heat is dangerous to most of the population, especially those without proper cooling during the nighttime hours. Meanwhile, the Valley is expected to see mainly Minor to Moderate Heat Risk as the forecasted highs are likely to be just a few degrees above normal, though are just as likely to be in the lower triple digits throughout the week. And according to the latest model runs, this pattern of above normal temperatures is likely to continue into the week after next, as the Climate Prediction Center continues to have our area under that criteria from Day 6 through Day 14. The time period from the 28th of July through the 3rd of August is also highlighted for a slight risk (20-40%) for hazardous temperatures.

AVIATION

VFR conditions expected 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

None.