textproduct: San Joaquin Valley

KEY MESSAGES

1. Seasonally average weather returns this weekend. Next warm- up expected later next week.

2. Another monsoon push early next week increases probability of Sierra Nevada thunderstorms.

DISCUSSION

Heat Dome being modified by traveling disturbance as it continues moving through the Upper Mid-Week this Friday. While winds have diminished with the exiting disturbance, a drop in temperatures remain in its wake. So far this morning, 24 hour temperature change reflex a drop of 3 to 5 degrees from Thursday Morning. Therefore, will see max temperatures reach the upper 90s to around 100 degrees this Friday (around seasonal normal). Probability of Exceedance (PoE) of reaching 105 degrees remains below 10 percent through next Wednesday with a slight rise by Thursday. PoE of 100 degrees does take a downward turn through Saturday and slowly rises through the middle of next week. Therefore, will expect near seasonal normal temperature (upper 90s to near 100 degrees) for a good portion of the period with a little uncertainty on the timing of the next heat wave.

Outside of the Sierra Nevada Crest, will expect dry conditions through the weekend with a return of the monsoon moisture early next week. Current guidance indicates a slight (less than 10 percent) probability for thunderstorms across the crest through the rest of the work week. Furthermore, without the abundant mid and upper level moisture observed in days past, any thunderstorms that do form are not favorable for severe weather impacts such as heavy rainfall and large hail. At this point, Probability of Measurable Precipitation above 20 percent is expected to the Mojave Desert by next Wednesday and spread further toward Central California later next week.

Longer range ensemble analysis has the heat dome centered closer to the Mid-West as the associated flow pattern pushes the monsoon moisture back toward Central California late in the weekend. Climate Prediction Center (CPC) is indicating that the extended time frame of the 6 to 10 day period will remain on the warm side. Current CPC analysis has a 40-50 percent chance that temperatures will lean toward above normal conditions.

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.