textproduct: San Joaquin Valley

KEY MESSAGES

1. A significant to extreme fire risk exists in eastern Kern and eastern Tulare counties Friday through Sunday.

2. Strong wind gusts are expected through Sunday in the Tehachapi Mountains and Mojave Slopes as low pressure moves through. Wind Advisory in effect for Kern County.

3. A warming trend is expected this weekend and into next week.

DISCUSSION

An approaching low pressure system will cross the area later today. Below-average PWAT values will limit any precipitation chances with this system, with only the mountains expected to have any chance (5-15% above 5,000 feet) of precipitation. Any snow accumulation will be limited to less than an inch. The precipitation threat ends tomorrow morning.

Of greater concern with this system will be wind. A Wind Advisory is currently in effect for Kern County, with gusts in excess of 50 mph expected in the Piute Walker Basin, Tehachapi, and Mojave Desert Slopes. As we approach the weekend, the low is expected to retrograde and stall over Baja California while a potent ridge builds off the coast. This will create a conveyor built of northeasterly winds in the Kern and Tulare County mountains, which will result in significant downslope acceleration and drying, with gusts currently forecast to approach 75 mph. While fuels are still relatively moist, the wind and dry air are of a magnitude significant enough to create extremely volatile conditions in southeastern Tulare and eastern Kern Counties Friday through Sunday, and as such, appropriate fire precautions should be taken during this period.

The area should experience a warming trend after Friday, with temperatures gradually approaching the upper 70s in the Valley into early next week. While the low pressure and winds will provide improved ventilation, abundant surface-level moisture will keep a risk for fog, likely patchy, across the Valley Thursday morning, particularly in the eastern portions of the Valley (10-15% chance of visibilities below a quarter-mile).

AVIATION

VFR conditions prevail until 11Z, when MVFR conditions are possible in mist and low clouds in the Valley, particularly in the eastern half of the Valley.

AIR QUALITY ISSUES

No air quality issues currently.

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 4 PM this afternoon to 10 AM PST Thursday for CAZ333-334-338.