textproduct: San Joaquin Valley

KEY MESSAGES

1. Minor Heat Risk through Tuesday as temperatures remain at or below seasonal normal values.

2. A warming trend in temperatures starts on Wednesday as the region will see the return of heat during the latter part of the period. Thursday looks to be the hottest day with a greater than 70% chance of a Moderate Heat Risk.

DISCUSSION

The cut-off low pressure system that drove today's mountainous thunderstorms will be moving east through tomorrow, leaving our area on the leeside of its axis. This will cause thunderstorm chances to fall off a cliff as drier air takes over. Temperatures are also expected to a few degrees mainly due to the lack of cloud cover caused by this drier air.

As this cut-off rejoins the larger pattern, a ridge is expected to build in from the east, leading to a continued rise in temperatures from Wednesday into Thursday, the latter of which looks to be the hottest day in this upcoming week. Valley highs on that day are expected to be in the upper 90's, with the southwest side of the Valley seeing a 40-60% chance for triple digits in the afternoon with the rest of the Valley at 15% or less. Thursday will also see at least a 70% chance for Moderate Heat Risk, which affects the more sensitive people among the population, such as elderly people, children, and those with chronic illnesses.

Thankfully, this heat will be short lived, as the ridge is pushed back east by an incoming trough moving through the Pacific Northwest, reducing 500mb heights and bringing temperatures back down to around normal by Saturday. Slightly below normal temperatures are expected by Sunday into Monday of next week. Typical of the transitional season, this temperature rollercoaster is expected to continue through next week as troughs are able to dig further south and ridges become less able to produce summer-like conditions due to the reduced amount of sunlight in the day. Looking to the long term forecast, the Climate Prediction Center has our CWA under the leaning to likely above normal category for temperatures for both the 6 to 10 day and 8 to 14 day outlooks (normal being in the mid to upper 80's for this time of year), suggesting a ridge may build over Central California again.

AVIATION

MVFR visibility due to smoke in the vicinity of the Dome Fire in Yosemite NP through at least this evening. Otherwise, VFR conditions prevailing 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

Lake Wind Advisory until 5 AM PDT Tuesday for CAZ300.