textproduct: San Joaquin Valley

KEY MESSAGES

1. Below average temperatures remain in place for the next several days with localized rain and snow showers (above 9,000 feet) across the area from tonight through the start of the weekend.

2. More substantial precipitation will move into our area by Saturday evening with a 50-65% chance of at least a half an inch of rainfall from Saturday evening through mid-day Sunday.

3. A Winter Weather Advisory has been issued for the higher elevations along the Sierra Nevada mountains with a 30-50% chance of greater than 4 inches of snowfall above 7,000 feet, and a 50-70% chance of greater than 10 inches of snowfall above 9,000 feet.

DISCUSSION

With a trough over our area and a low pressure system to our north over the Pacific Northwest, the trend of below average temperatures is expected to continue for the next several days. High level clouds remain present over parts of our area and are expected to remain in place through the day today. More widespread cloud cover will likely move into our area this evening with chances for localized, mostly light precipitation. With lift in place due to the fact that we are on the leading side of the trough, precipitation is expected to form over the Pacific Ocean and move east into our region. Rainfall within the San Joaquin Valley however is expected to remain only light to moderate in nature, localized, and mostly conversational with no significant accumulations expected. This localized light precipitation could continue however through at least early this weekend before more substantial rainfall chances begin later on in the day Saturday. In addition to the rainfall in the valley, light snow remains possible above 9,000 feet through Saturday morning, with the probability of greater than 4 inches of snow at around 50-70% above 9,000 feet in elevation, probabilities are higher at the highest elevations. In addition to the rain and snowfall, some localized gusty winds are possible especially along the Sierra Nevada crest with the probability of wind gusts exceeding 25 mph at around 50-65% from late Thursday night into early Friday morning.

Recent trends have increased with regards to precipitation amounts this coming Saturday evening into Sunday morning. An anomalously strong trough from the Pacific Northwest will dig south into our region on Saturday with a a low pressure system moving directly over southern California. While the low pressure system will remain well to our south, the trough will result in ample lift within our area. As a result, accumulating and more widespread precipitation will likely influence our region from Saturday evening through Sunday afternoon. The probability of a half an inch of rainfall is 50 to 65% from Saturday afternoon though Sunday afternoon across the Central Valley. The probability of three quarters of an inch of rainfall decreases to around 35 to 50% in the valley. Probabilities are lower in the Mojave Desert with higher probabilities in the Sierra Nevada mountains. In addition to the rainfall, snow is likely in the Sierra Nevada mountains above 7,000 feet, hence a Winter Weather Advisory has been issued. The probability of greater than 4 inches of snow above 7,000 feet is 30-50% over 24 hours through 4 pm Saturday. Above 10,000 feet there is a 50-70% chance of more than 10 inches of snow through the same time period.

This system will likely move out of the entire area by sometime Sunday afternoon with dry conditions and warmer temperatures expected next week. The majority of ensemble runs and models pick up on a ridge of high pressure moving into our area through much of next week. Temperatures will potentially warm up into the 70s by Tuesday of next week, with the probability of exceeding 70 degrees in the valley at around 45-60%. As of now, mostly dry conditions with little to no rainfall is expect through next week as well. The Climate Prediction Center (CPC) has a 50-60% chance for above average temperatures and near normal precipitation in the 8-14 Day Outlook.

AVIATION

A reduction in visibility to around 4-5 statute miles due to haze is possible tomorrow morning at KFAT, KVIS, and KBFL. 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

Winter Weather Advisory from 8 AM Saturday to 7 AM PDT Sunday for CAZ323-326>328-330.