textproduct: San Joaquin Valley

KEY MESSAGES

1. Temperatures will remain above average through today. Record highs are possible again in the valley areas.

2. Practice cold water safety, as waterways will be running cold and fast over the next several days.

3. There is good confidence for a storm to pass through central California Monday night through Wednesday this week and will bring valley rain, mountain snow and strong winds to the region.

DISCUSSION

Satellite loops show high and mid-level clouds passing over the forecast area today with an upper-level ridge of high pressure persisting over the western U.S. Some mid-level moisture remains, so cumulus clouds redevelop over the Sierra Nevada crest by this afternoon. Record high temperatures in the San Joaquin Valley will once again be challenged today with highs in the upper 80's to near 90 degrees in the warmest locations. The chance for a 90 degree reading is currently at 15-25 percent with a 70-80 percent chance of a high at 85 degrees or warmer. A pattern shift occurs late Monday with a trough of low pressure arriving. Some lowering of temperatures is forecast on Monday, but no significant cooling in terms of high temperatures will take place until Tuesday. The probability for highs to reach 85 degrees at the warmest spots is still 50-60 percent for Monday.

Precipitation chances begin late Monday night into Tuesday morning over the Sierra Nevada with chances entering much of the San Joaquin Valley through the day on Tuesday. Lingering chances remain for the mountains and foothills (25-35 percent) into Wednesday with slight chances (15-20 percent) in northern portions of the Valley, mainly towards Merced County. Precipitation amounts remain light, or at 0.25 to 0.50 inch in the Sierra. As for the Valley, amounts are at 0.10 or less. Forecast snow levels are at 7,000 feet, with amounts generally at 3-6 inches for Tuesday until Wednesday. A 20-30 chance for precipitation remains in the Sierra Nevada into Thursday, mainly north of Kern County, although precipitation chances diminish by the afternoon. In addition, there is a slight chance for thunderstorms over the Sierra and mainly northern portions of the San Joaquin Valley for Tuesday afternoon. Otherwise, much cooler temperatures and increased winds over the prone areas in eastern Kern County and the Sierra Nevada crest are in store for this week. Temperatures warm back to above average by next weekend as high pressure ridging returns, or just in time for Easter.

Overall, the latest 6-10 day and 8-14 day outlooks show the odds tilted towards above average temperatures and below average precipitation.

AVIATION

VFR conditions will prevail across central California across the next 24 hours.

FIRE WEATHER

Temepratures remain near record highs through today with low minimum RH values resulting, curing fine fuels across the region and leading to conditions conducive for isolated grass fires to develop. Light terrain driven winds expected through today, but strong winds return on Monday, mainly over the higher terrain. No precipitation is expected today, and then a storm will enter the region on Monday with a chance of rain and snow on Tuesday and Wednesday.

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.