textproduct: San Joaquin Valley

KEY MESSAGES

1. There is a high confidence in a significant change in the overall weather pattern with temperatures continuing to cool down and precipitation midweek.

2. The first wetting rainfall throughout the entire area is likely with a 55-65% chance of at least a half an inch of rainfall by Thursday evening.

3. Snowfall is likely above 8,000 feet in elevation with a 60-70% chance of at least 4 inches of snowfall (probabilities increase further at higher elevations).

4. The Storm Prediction Center (SPC) has western Kern County in a marginal (level one out of five) risk for severe weather with a 5-14% chance for severe winds tomorrow.

DISCUSSION

Some isolated thunderstorms have developed in Tulare County along the Sierra Nevada crest; otherwise, increasing cloud cover has been occurring this evening. Precipitation is projected to spread over the forecast area by Wednesday morning and continue into Thursday. The bulk will occur Wednesday afternoon until Thursday morning. Many locations can expect a total of one quarter to one half inch in the San Joaquin Valley, while there is near 60 percent chance of exceeding a half inch. The Flood Watch remains in effect for much of Kern County and the higher terrain along the west side of the San Joaquin Valley up to southwestern Fresno County near Coalinga. Higher amounts of precipitation are likely to occur over the Sierra Nevada from the foothills to about 8,000 feet. While some nuisance flooding is also a possibility in these areas, we anticipate less runoff except near burn scars. We are still looking at a good chance for at least a few inches of snow above 8,000 feet in the Sierra Nevada. We will continue the Winter Weather Advisory for these areas from Wednesday morning to Thursday morning. There is a 10-20 percent chance of thunderstorms during Wednesday and Thursday throughout the forecast area. Also, a marginal risk of severe thunderstorms is shown over western Kern County with strong winds as the primary threat, per the latest SPC Day 2 Convective Outlook.

For Friday through next Tuesday, we are looking at continued cooler temperatures and mainly dry conditions. Although temperatures will warm up by several degrees for the weekend until Monday, we are projecting highs mainly in the 70s for the warmest locations. There is a slight chance of precipitation for the middle of next week, but with much uncertainty at this time.

AVIATION

Isolated thunderstorms after 18Z Wednesday in the Sierra Nevada along with IFR conditions and mountain obscurations. Elsewhere, MVFR in showers after 21Z Wed with isolated thunderstorms. Winds mainly up to 10 kts at the TAF sites, mainly from the east. 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

Flood Watch from 8 AM PDT Wednesday through Thursday evening for CAZ308-309-313-314-316-332>339. Winter Weather Advisory from 11 AM Wednesday to 11 AM PDT Thursday for CAZ323-326>328-330-331.