National Weather Service - Discussion

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Area Forecast Discussion

National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Monday, October 26 2020 - 5:39 PM PDT

UPDATE... Updated Air Quality Section

SYNOPSIS...A cooling trend will continue, with temperatures remaining below normal through Tuesday. A heightened fire danger continues over the mountains and desert areas into Tuesday due to locally gusty winds and low humidity. A warm up is expected for the latter half of the week.

DISCUSSION... The potent low pressure system pushing through the Great Basin region has brought further cooling to our area, with strong and gusty northeasterly winds across the mountain, foothill and desert zones. Current 24 hr temperature trends are mostly running down around 3-9 degrees. The much drier air mass has lowered humidity values into the single digits in many mountain, foothill and desert locations. The gusty winds and very dry conditions are creating dangerous fire weather conditions and A Red Flag Warning remains in effect for these areas.

As the low pressure system drops further south our offshore flow pattern will continue, with the strongest winds shifting southward as well. Models show another surge in wind speeds however across the Sierra zones later tonight into Tuesday. With the continuing low humidities and gusty winds. The Red Flag Warning will remain in effect through Tuesday. Overnight lows tonight in this colder airmass will run around 4-8 degrees below climo and some desert locations should see temperatures bottoming out below the freezing mark. Tuesday highs are also expected to run around 4-8 degrees below seasonal averages.

As the low pressure system begins to swing out on Tuesday, a ridge of high pressure will begin to build inland. By Wednesday, this building ridge will bring warming temperatures and calmer winds. Temperatures are progged to warm to a bit above average by the end of the week. Models develop a low pressure system off the California coast by early next week and warming conditions will be put on hold as the low drifts ashore. No precipitation is shown through the forecast period.

AVIATION... Local MVFR/IFR visibilities can be expected in smoke and haze over the Sierra during the next 24 hours. VFR conditions will otherwise prevail over the central California interior during this time. Periods of wind gusts over 40 KT can be expected over mountain ridges and through and below passes and canyons.

AIR QUALITY ISSUES... Please see SFOAQAHNX for an Air Quality Alert.

On Tuesday October 27 2020... Unhealthy for sensitive groups in Kern... Kings and Tulare Counties. Further information is available at Valleyair.org

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 an/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 5 PM PDT Tuesday for CAZ298-299-590>597.