textproduct: San Joaquin Valley

KEY MESSAGES

1. Chances for dense fog in the San Joaquin Valley continue this morning, then return after midnight Sunday.

2. Dry conditions and a brief warm up are expected through the weekend before temperatures dip back below normal next week.

3. Another trough moving in out of the Pacific Northwest may bring precipitation to the region once again by next Friday.

DISCUSSION

It's time to blare the foghorns! After a rainy Wednesday and Thursday, overnight lows in the lower 50s to upper 40s with clear skies allowed the first dense fog of the season to develop across the San Joaquin Valley and remain past sunrise. As of 9 AM, multiple weather stations along Highway 99 were still reporting visibility between one-half to one-quarter mile, including the Fresno Yosemite and Visalia Municipal airports. The Dense Fog Advisory for the San Joaquin Valley remains in effect until 11 AM this morning, so areas of quarter-mile visibility will still remain until then. There is also a small (10-30%) chance for visibility one-quarter mile or less between midnight to 9 AM tomorrow morning in the central San Joaquin Valley. So while chances are low, tomorrow morning might bring our second dense fog event of the season.

Even with stubborn morning fog, high temperatures across the valley and desert are expected to be in low-to-mid 70s today and the mid-to-upper 70s on Sunday. Weak high pressure will remain over Central California through the start of the work week, after which high temperatures will cool to about 5 degrees below normal. Models then indicate rainfall chances enter back into the forecast starting Thursday, as another area of low pressure slides southward from the Pacific Northwest by Friday.

According to the National Blend of Models (NBM), the best time for rain and snow will Friday through Sunday morning, with a 50% chance for rain in the San Joaquin Valley & Mojave desert, and 70% chance for rain or snow in the Sierra Nevada. Expected and high-end rain/snow scenarios between this 72 hour period vary widely. So, like most forecast, a few more days will be needed before we can start to discuss expected storm totals and forecast confidence. Until then, have a great weekend!

AVIATION

Areas of MVFR to IFR due to lowered visibility until 18Z. Otherwise, VFR conditions will prevail 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

Dense Fog Advisory until 11 AM PDT this morning for CAZ302-303- 306-307-310>312-315.