textproduct: San Joaquin Valley

KEY MESSAGES

1. Temperatures will remain above average through the weekend. 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 next Monday through Wednesday, bringing valley rain, mountain snow and strong winds to the region.

DISCUSSION

Southwest flow over central California will drive warmer conditions in to the region through the weekend, with daily record highs once again coming under threat. Ensemble guidance from the NBM shows around a 80 to 90 percent probability for maximum temperatures to exceed 85 degrees in the San Joaquin Valley both Saturday and Sunday. Some locations, especially in the western valley areas have up to a 100 percent probability for these temperatures and a 40 to 50 percent probability to exceed 90 degrees. These temperatures will continue to bring minor heat risk to the area through to Monday before a swift pattern change sets up.

Cluster analysis continues to show good confidence for a broad low pressure trough to pass through the western US Monday through Wednesday that will introduce moisture to California. Over a 48 hour period ending Thursday morning, there is a 30 to 40 percent probability for rainfall to exceed one-tenth of an inch in the northern San Joaquin Valley (north of Hanford and Visalia), with 20 to 30 percent for the south valley. Over this same time frame, there is a 50 to 60 percent probability for snowfall to exceed two inches in the higher elevations of the Sierra Nevada; this is a downtrend in overall snowfall totals from yesterday. Snow levels continue to be projected at 7,000 to 8,000 feet during the passage of the trough.

AVIATION

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

FIRE WEATHER

Temepratures will continue to rise into the weekend with RH values falling as a result, curing fine fuels across the region and leading to conditions conducive for sporadic grass fires to develop. Light terrain driven winds expected through the weekend. Strong winds return on Monday, mainly over the higher terrain. No precipitation is expected through the weekend. 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.