textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. Lingering precipitation will continue falling this Sunday with a slight chance for afternoon thunderstorms across the Sierra Nevada.

2. Clearing overnight will increase the potential for early morning fog on Monday. Dense Fog Advisory issued.

3. Below to near normal temperatures continue through much of the week.

DISCUSSION

The Halloween Storms last hurrah is upon us as lingering showers continue this November 1st (Day of the Dead). Trough axis is still over California this morning as enough lift will exist this afternoon for a slight chance of convective showers. While instability this morning is rather weak, day-time heating as a strong jet rounding the backside of the trough will support a continuation of afternoon showers before clearing occurs this evening. Afterward, with the precipitation amounts observed during the last 24 hours, the potential for fog will increase going into Monday Morning.

Ensemble upper air analysis will place the high pressure ridge over California by Monday Morning. This timing will increase the potential of fog (dense fog) across the San Joaquin Valley during the early morning through sunrise. Yet, upper-air analysis still has some strong winds rounding the trough (ahead of the ridge axis) that may provide some mixing during the early morning hours. Therefore, short range ensemble analysis shows a reduction in visibility that approach dense fog criteria. Will consider a dense fog advisory for portions of the San Joaquin Valley where fog formation will be favorable.

Long term analysis is showing a weak disturbance making its passage through the Pacific Northwest around the mid-week period. Current timing has the disturbance over the area on Tuesday/Wednesday before a strong ridge shifts in later in the week. Uncertainty does exist on the deepness of the disturbance and how far south it will dig. Ensemble precipitation analysis shows almost no accumulation reaching Central California. Therefore, will expect the disturbance to remain north of the area with zonal wind flow maintaining near to below normal temperature values during much of the period. By next Sunday, ensemble temperature analysis has the Probability of Exceedance of reaching 75 degrees above 30 percent with the south valley climbing to 60 percent. Climate Prediction Center does place Central California in the 50-60 percent (Likely Above) of having temperatures above seasonal normal.

AVIATION

Periods of MVFR conditions will continue across the lower elevations with IFR conditions in the Sierra Nevada until 18Z Sun. VFR conditions return for the local area after 03Z Mon. 20% chance for IFR/LIFR conditions at KVIS between 12Z-18Z Mon.

AIR QUALITY ISSUES

On Sunday November 1 2026, Fireplace/Wood Stove Burning Status is: Burning Discouraged in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties, and Kern (Greater Frazier Park Area), and Sequoia National Park and Forest.

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.