530
FNUS22 KWNS 180638
FWDDY2
DAY 2 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0138 AM CDT THU OCT 18 2018
VALID 191200Z - 201200Z
..SYNOPSIS
A UPPER-LEVEL ANTI-CYCLONE IS FORECAST TO BE CENTERED OVER THE
PACIFIC NORTHWEST ON DAY 2/FRIDAY, WHILE A WEAK UPPER LOW REMAINS
JUST OFF THE COAST OF SOUTHERN CA. SURFACE HIGH PRESSURE OVER GREAT
BASIN AND NORTHERN/CENTRAL ROCKIES WILL FOSTER OFFSHORE FLOW ACROSS
SOUTHERN CA THROUGH THE PERIOD.
..PORTIONS OF SOUTHERN CA
THE SURFACE PRESSURE GRADIENT FROM LAX-TPH AND LAX-DAG IS FORECAST
TO STRENGTHEN CLOSE TO CRITICAL THRESHOLDS FRIDAY MORNING, AND
MODERATE TO PERHAPS STRONG/GUSTY NORTHEASTERLY WINDS ARE EXPECTED.
THE BEST POTENTIAL FOR LOCALLY CRITICAL-LEVEL WINDS APPEARS TO BE
FOR THE HIGHER TERRAIN OF VENTURA AND LOS ANGELES COUNTIES, WHERE
ISOLATED SUSTAINED WINDS OF 20-25 MPH COULD OCCUR, WITH SOME HIGHER
GUSTS TO 35-40 MPH POSSIBLE. WIDESPREAD 15-20 MPH OFFSHORE FLOW
APPEARS LIKELY ELSEWHERE IN MUCH OF THE LOWER TERRAIN/VALLEYS OF
SOUTHERN CA. POOR OVERNIGHT RH RECOVERY IS EXPECTED FROM LATE
THURSDAY EVENING INTO FRIDAY MORNING GIVEN THE GRADUALLY
STRENGTHENING LOW-LEVEL FLOW AND LOCAL DOWNSLOPE WARMING/DRYING
EFFECTS. AS DIURNAL HEATING AND MIXING OF THE BOUNDARY LAYER OCCURS
FRIDAY MORNING AND AFTERNOON, RH VALUES WILL EASILY FALL INTO THE
10-15% RANGE ACROSS MOST OF COASTAL SOUTHERN CA.
SOME CONSIDERATION WAS GIVEN TO INTRODUCING A CRITICAL AREA FOR
PARTS OF VENTURA AND LOS ANGELES COUNTIES, BUT THE LACK OF STRONGER
MID TO UPPER-LEVEL WINDS AND THE MARGINAL FORECAST SURFACE PRESSURE
GRADIENT BOTH SUGGEST A BROAD ELEVATED DELINEATION IS APPROPRIATE
FOR NOW. A CRITICAL UPGRADE MAY BE NEEDED IN A LATER UPDATE IF THE
FORECAST SURFACE PRESSURE GRADIENT STRENGTHENS ANY FURTHER.
..GLEASON.. 10/18/2018
..PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT
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