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FNUS21 KWNS 201700

FWDDY1



Day 1 Fire Weather Outlook  

NWS Storm Prediction Center Norman OK

1100 AM CST Mon Jan 20 2025



Valid 201700Z - 211200Z



...EXTREMELY CRITICAL FIRE WEATHER AREA FOR THE SAN GABRIEL

MOUNTAINS WEST TOWARDS THE SANTA MONICA MOUNTAINS AND SANTA SUSANA

MOUNTAINS...INCLUDING THE MALIBU COAST...

...CRITICAL FIRE WEATHER AREA FOR MUCH OF SOUTHERN CALIFORNIA...



The previous forecast (see below) remains on track, and no changes

were needed with this update. The LAX-DAG pressure gradient is

quickly tightening this morning, with the latest reading (as of 16Z)

around -3.8 mb. This trend will continue into the overnight/early

morning hours, yielding rapidly strengthening surface winds and

decreasing RH. The onset of critical to extremely critical

conditions is expected by early afternoon, with the most volatile

conditions still expected over the wind-prone Santa Ana corridor of

northern/western Los Angeles County into eastern Ventura County

during the overnight/early morning hours. Extremely critical

conditions will persist into Day 2/Tuesday morning here.



..Weinman.. 01/20/2025



.PREV DISCUSSION... /ISSUED 0208 AM CST Mon Jan 20 2025/



...Synopsis...

While most of the CONUS is dominated by cold air and high pressure,

a strong, positively-tilted mid-level trough will move southward

across California, with a highly amplified mid-level Pacific ridge

following behind it. As the trough axis reaches southern California

Monday afternoon, intensifying surface pressure gradients will

result in the development of strong Santa Ana winds. 



The 00Z HREF guidance and global ensembles continue to forecast

strong LAX->DAG pressure gradients ranging from -8 mb to -11 mb,

with wind speeds trending upward to 40-45 MPH sustained (gusting 70

- 100 MPH on the mountains, 50 - 80 MPH in the valleys/coastal

regions). In addition to the upward trend in wind speed and gust

forecasts, relative humidity values have trended significantly

drier, with values as low as 2%-5%. These Extremely Critical

fire-weather conditions, supporting rapid wildfire onset and spread,

will begin Monday afternoon and reach peak intensity Monday evening

into Tuesday morning. The area of greatest risk lies from the San

Gabriel Mountains westward into the Santa Monica Mountains, the

Malibu Coast, and the Santa Susana Mountains. 



Elsewhere, Critical fire-weather conditions extend southward to the

U.S./Mexico border, where strong (and critically dry) offshore winds

will persist overnight into Tuesday morning.



...Please see www.spc.noaa.gov/fire for graphic product...



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