textproduct: San Joaquin Valley

UPDATE

Updated for Key Messages and HNX Advisories.

KEY MESSAGES

1. Temperatures drop drastically into early next week.

2. High wind gusts over 35 mph are likely into Sunday night (65-80% chance) over the San Luis Reservoir with a Lake Wind Advisory issued. Gusts also increase for the Mojave Desert and adjacent slopes as well as the West Side Mountains with a Wind Advisory in effect.

3. There is a marginal (5-15% chance) risk for excessive rainfall in the Mojave Desert and along southern portions of the Sierra Nevada today.

4. There is around a 50-90% chance for 72 hour snowfall greater than 2 inches above 9000 feet from Sunday into Wednesday morning.

DISCUSSION

Saturday night had an eerie sunset across much of the southern portion of the Valley in combination with cooler temperatures made it feel like October. Radar has already begun to pick up showers from the moisture of Tropical Storm Rachel over the Desert.

Temperatures continue to drop on Sunday as there is a 70 to 90 percent chance of highs below 80 degrees. The higher elevations of the Sierra Nevada has a 20 to 50 percent chance of a tenth of an inch. However, the moisture will especially continue in the Desert with a 30 to 60 percent chance of half of an inch. The Valley, however, has a 10 percent chance or less of any rain on Sunday and Monday. The winds also pick up in the desert with a 65 to 100 percent chance of gusts maxing out at least 40 mph, thus a Wind Advisory is in effect until Monday morning for the Desert.

Monday will be the coolest day of the week as highs have a percent chance of reaching 70 degrees. The Sierra again will see more showers with a 45 to 65 percent chance of a tenth of an inch while the foothills have a 15 to 25 percent chance. The Desert, however, will get a reprieve with a 10 percent chance or less of a tenth of an inch. Snow levels on Monday drop to 7,000 to 7,500 feet. Despite this, only a 50 to 90 percent chance of 2 inches is expected above 9,000 feet in total from Sunday through Wednesday morning while only a 35 to 60 percent chance of a dusting above 7,000 feet.

Temperatures climb again on Tuesday as the trough slides away. However, the warmup will continue for the rest of the week as another ridge moves in and strengthens over most of the U.S. But, the chance for 90s is like a horror creature as it doesn't want to go away as we have a 40 to 50 percent chance of 90s over next weekend. The CPC continues to show a strong signal for above average temperatures and below average precipitation in the 6-10 and 8-14 day outlooks.

AVIATION

5 to 15 percent chance of thunderstorms after 18Z Sunday. IFR to MVFR conditions over the Sierra Nevada in clouds and showers. 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

Wind Advisory from 1 PM Sunday to 11 PM PDT Sunday for CAZ304, CAZ308, and CAZ313. Wind Advisory from 2 PM Sunday to 8 AM PDT Monday for CAZ337>339. Lake Wind Advisory until 11 PM PDT Sunday for CAZ300.