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

High pressure remains centered over the Great Basin/Four Corners region this morning. Moisture to the south of the system is being drawn northward over California, resulting in scattered cloud cover over the Sierra Nevada and Kern County Mountains and Desert areas. Additional moisture in the form of outflow from Post-Tropical Cyclone Elida is streaking along the Pacific Coast and Coastal Range on the west side of the region. The additional moisture across central California today is expected to condense as it encounters the local terrain, especially along the Sierra Nevada range, which has a chance to produce scattered showers and thunderstorms along the crest. From Yosemite NP to Sequoia and Kings Canyon NP, there is a 20 to 30 percent probability for thunderstorms to occur this afternoon. Any storms that develop have potential for small hail, gusty and erratic winds, locally intense rainfall, and cloud-to-ground lightning; lightning has potential to spark new wildfires on dry fuels outside of storms. However, over the next 24 hours, there is a 70 to 80 percent probability for these showers and thunderstorms to produce at least one tenth of an inch over the aforementioned areas, reducing the risk for dry lightning to occur. This pattern will continue through Wednesday, with the peak being Tuesday, where there is up to a 40 percent probability for thunderstorms to occur along the Sierra Crest.

Meanwhile, the high pressure will result in average temperatures in the San Joaquin Valley and Mojave Desert for much of the week. Today and Tuesday, there is a 60 to 70 percent probability for afternoon highs to exceed 100 degrees in the central valley, which rises to 80 to 90 percent on Wednesday, before returning near 50 to 60 percent for the remainder of the work week. However, in the desert areas, warmer temperatures on Wednesday will progressively warm through the weekend. On Wednesday, there is a 70 to 80 percent probability for maximum temperatures to exceed 105 degrees, which rises to 80 to 90 percent each subsequent day. In addition, there is a 50 to 60 percent probability for afternoon highs to exceed 110 degrees for the likes of Ridgecrest and China Lake each day Thursday through Monday. Major HeatRisk is anticipated for this area resulting from not just the hotter daytime temperatures, but also warmer morning lows, with a 50 to 60 percent probability for minimum temperatures to exceed 80 degrees in Ridgecrest Thursday and Friday.

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.