textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. There remains at least a slight chance for additional, mainly light, precipitation in the Sierra Nevada until Friday evening.

2. Temperatures will warm up to near average this weekend with dry conditions in place into much of next week.

DISCUSSION

This afternoon and early evening became quite active with scattered showers and isolated thunderstorms across the forecast area. The heaviest rain showers occurred in Merced, which prompted a Flood Advisory. Some reports of street flooding were received for southwestern portions of Merced, as over an inch of rain fell in about an hour (around 4:30 to 5:30 PM). However, precipitation has mainly ended, except for light showers, mainly Fresno County northward. We have let the Flood Watch expire at 8 PM PDT. Shower coverage will gradually decrease overnight tonight. Depending on how much clearing we observe tonight, some patchy fog is possible during late tonight into Friday morning in the Central Valley. Some light rain and snow showers may redevelop over the Sierra Nevada and Kern County mountains Friday morning and afternoon, although chances remain low to moderate (20-40%). Any snow will fall above 7,500 feet. We remain underneath an upper- level trough on Friday and will gradually shift inland into Saturday. Friday's highs remain several degrees below average, and temperatures moderate on Saturday. Also, if valley fog doesn't develop tonight, we might see some late Friday night into Saturday morning.

Seasonably warm temperatures take place Sunday and Monday, though with weak high pressure ridging. Some minor cooling will occur during the middle of next week as troughs pass over the Pacific Northwest. Highs will be mainly in the 70s at the warmest locations. Overnight lows will be relatively cool, or at least typical for this time of year.

Conditions remain dry through at least late next week. There is a slight chance for precipitation to return to the forecast area by the end of next week.

AVIATION

IFR due to fog/mist possible (30-50 Percent chance) during 12Z-17Z Friday in the San Joaquin Valley. IFR and mountain obscurations in showers over the Sierra Nevada and the Kern County mountains from 15Z Fri to 00Z Saturday. 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

None.