textproduct: San Joaquin Valley

KEY MESSAGES

1. Minor Heat Risk through the weekend into Monday as temperatures cool to early fall normals. Temperatures climb beginning Tuesday.

2. Low pressure trough approaches California Sunday, bringing cooler temperatures and a possibility for precipitation along the Sierra Nevada mountains.

3. Low but notable chances (10-20%) for thunderstorms across the Sierra Nevada Monday.

4. Lake Wind Advisories for Lake Isabella and San Luis Reservoir through late this evening.

DISCUSSION

This morning, we had high clouds advect in from the southwest thanks in part to a disturbance over the Pacific Northwest. This disturbance also has brought a slight cooldown in temperatures from the near triple digits we had on Thursday. However, with that disturbance lifted more towards Canada, the onshore flow becomes more prominent today leading to temperatures to continue to drop slightly. Winds also pick up with the onshore flow aloft that Lake Wind Advisories have been issued for this afternoon and evening for Lake Isabella and San Luis Reservoir.

Temperatures plummet even more Sunday and Monday as another trough slides into our area. RH values improve with this trough thanks to some moisture being advected from Hurricane Odalys. Monday will be very Fall-like with a 85 percent chance and higher of highs below 85 degrees. The Sierra Nevada has a 10 to 20 percent chance of thunderstorms on Monday, however, the Valley has a 5 percent chance or less of seeing any real precipitation with this system. Winds also pick up with this system. Sunday sees wind gusts pick up especially in Eastern Kern County that another Lake Wind Advisory will be issued for Lake Isabella. Mojave sees a 45 percent chance of 45 mph gusts on Sunday.

The trough slides out on Tuesday and a ridge builds in and will strengthen through the week bringing temperatures back up. Thursday through next Saturday has a 45 to 55 percent chance of highs of at least 95 degrees in the Valley. As the trend has been holding for many weeks, the CPC continues to favor above average temperatures. The 6-10 day outlook has a 50 to 60 percent chance and the 8-14 day outlook jumps to 60 to 70 percent chance of above average temperatures.

AVIATION

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

Lake Wind Advisory from 5 PM this afternoon to 11 PM PDT this evening for CAZ300. Lake Wind Advisory from 2 PM this afternoon to 8 PM PDT this evening for CAZ332.