636
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
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