textproduct: San Joaquin Valley

KEY MESSAGES

1. Temperatures will be normal to slightly below normal through the weekend before below average by the middle of next week.

2. Precipitation chances may return again by next weekend.

DISCUSSION

Slight troughing over much of California will lead to a slow cooldown through tomorrow before a stronger wave moves through the region, causing further cooling from the mid to low 90's expected through tomorrow into the mid to low 80's throughout the Valley. These cool temperatures are expected to be maintained trough the rest of this week as the trough continues to sit over the west coast of CONUS.

Looking at the minRHs during this time period, they will continue to be dry throughout the region as the back side of the trough is situated over Central California. This effect will have the minRHs around 15-25% in the Valley and into the single digits for the desert. However, when the first strong wave moves in, minRHs will rise as more moist air is picked up from the south. This is expected to continue through the week into next weekend.

The forecast for next weekend is interesting, as there is very low, but slowly growing (so far), confidence in a yet to be named tropical system making a pass at our area by next weekend into the following week. So far, both the GFS and European models resolve with that system or a remnant of it producing significant rainfall across the Valley into the Sierra Nevada, though each has a different solution as to where the rain may fall as well as when, but both have it around Labor Day weekend into the actual holiday. This forecast is still evolving and is likely to change given how far out the event currently is, but the solution has stayed in both models for the past few model runs, so it is noteworthy enough to mention here.

AVIATION

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

None.