textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. Temperatures will remain above average through tomorrow.

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

3. A storm will pass through central California Monday night through Wednesday this week and will bring valley rain, mountain snow and strong winds to the region.

DISCUSSION

Tomorrow will bring another day of above average temperatures for central California as upper level flow continues from the southwest. However, a cooldown is expected starting Tuesday as a broad upper level trough tracks through the western US. Moisture pushing northward with enter the region Tuesday morning in the form of snowfall in the higher elevations of the Sierra Nevada and gradually extend downward towards the foothill areas and into the central Valley. Precipitation totals have had an uptick in the forecast from the previous few days, now with a 50 to 60 percent probability for one-tenth of an inch or more for the valley areas over 24 hours ending Wednesday morning, and a 30 to 40 percent probability for one quarter of an inch in the eastern valley. For the foothill areas below 7,000 feet, the probability for one-quarter of an inch is at 60 to 70 percent over the same time frame. Snowfall has also been on the uptrend above these levels, with a 60 to 70 percent probability for greater than six inches, but less than a 20 percent probability for a foot or more. High-impact winds remain in the forecast, especially for the Sierra Crest and in the Mojave Desert. There is a 50 to 60 percent probability for maximum wind gusts to exceed 45 mph in these areas on Monday and Tuesday, but on the backside of the approaching trough, similar probabilities are anticipated for 60 mph wind gusts for Wednesday and Thursday.

AVIATION

VFR conditions will prevail across central California across the next 24 hours. Strong winds developing over the Sierra Nevada Crest and across the Kern County Desert after 06Z Tuesday with surface winds gusting to G35KTS.

FIRE WEATHER

Temepratures remain above season averages through Monday with low minimum RH values resulting, continuing to cure 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.