Storm Prediction Center Day 1 Fire Weather Outlook
Created: Sun Dec 29 15:51:04 UTC 2013 (
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Storm Prediction Center Day 1 Fire Weather Outlook
Created: Sun Dec 29 15:51:04 UTC 2013 (
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Click for Day 1 FireWX Areal Outline Product
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 291550
DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0950 AM CST SUN DEC 29 2013
VALID 291700Z - 301200Z
...EXTREMELY CRITICAL FIRE WEATHER AREA FOR THE SANTA MONICA
MOUNTAINS OF SRN CA...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF LOS ANGELES AND
VENTURA COUNTIES SURROUNDING THE EXTREMELY CRITICAL AREA...
...COASTAL MOUNTAINS/FOOTHILLS OF SRN CA...
AN EXTREMELY CRITICAL AREA HAS BEEN INCLUDED FOR THE SANTA MONICA
MOUNTAINS OF SRN CA UPON COORDINATION WITH THE OXNARD WEATHER
FORECAST OFFICE. MORNING SUBJECTIVE SFC ANALYSIS PLACES A STRONG
PRESSURE GRADIENT BETWEEN 1035-MB HIGH PRESSURE IN N-CNTRL NV AND
SUB-1016-MB PRESSURES ALONG COASTAL SRN CA. THE ORIENTATION OF THIS
PRESSURE GRADIENT WILL REMAIN FAVORABLE FOR VERY STRONG WINDS OVER
THE SANTA MONICA MOUNTAINS. IN THIS AREA...COMPOSITE-NETWORK SFC
OBSERVATIONS AVAILABLE THROUGH MESOWEST INDICATE NNELY TO ENELY
WINDS ALREADY REACHING 25-40 MPH WITH GUSTS IN EXCESS OF 50 MPH.
INCREASING DIURNAL MIXING WILL LEAD TO FURTHER STRENGTHENING OF
THESE WINDS DURING THE NEXT SEVERAL HOURS AS AFFIRMED BY 1.33-KM AND
4-KM NAM GUIDANCE AND HIGH-RESOLUTION WRF GUIDANCE. SUSTAINED WIND
SPEEDS OF 30-40 MPH WITH GUSTS LOCALLY REACHING 50-70 MPH WILL BE
LIKELY ACROSS THE EXTREMELY CRITICAL AREA INTO THIS AFTERNOON BEFORE
GRADUALLY WEAKENING THIS EVENING INTO TONIGHT.
THE 12Z MIRAMAR NAVAL AIR STATION RAOB HIGHLIGHTS THE DRY AIR MASS
IN PLACE WITH A 0.23-INCH PW VALUE. SFC OBS ALREADY INDICATE RH FROM
12 TO 17 PERCENT IN CONJUNCTION WITH THE PREVIOUSLY MENTIONED WINDS.
AND...WITH CONTINUED DOWNSLOPE-INDUCED WARMING/DRYING AMIDST THE
ANTECEDENT DRY AIR MASS IN THIS OFFSHORE FLOW REGIME...RH VALUES
FROM 6 TO 9 PERCENT WILL BE LIKELY THIS AFTERNOON IN COMBINATION
WITH THE VERY STRONG WINDS. THIS WILL OCCUR AS TEMPERATURES RISE
INTO THE 60S TO AROUND 70 DEGREES. POOR OVERNIGHT RH RECOVERY IS
EXPECTED TONIGHT.
REGARDING FUELS...COLLABORATION WITH THE OXNARD WEATHER FORECAST
OFFICE SUGGESTS THAT FUELS ARE VERY DRY ACROSS THE EXTREMELY
CRITICAL AREA. GIVEN THE HIGH CONFIDENCE FOR THE MUTUAL
SPATIOTEMPORAL ALIGNMENT OF VERY STRONG WINDS...VERY LOW RH...AND
VERY DRY FUELS WITHIN A CONFINED AREA -- FAVORED BY FIXED
TOPOGRAPHIC INFLUENCES INCLUDING LOCAL-FLOW CHANNELING -- EXTREMELY
CRITICAL DESIGNATION IS WARRANTED FOR THE SANTA MONICA MOUNTAINS.
SURROUNDING THE EXTREMELY CRITICAL AREA...NO CHANGES HAVE BEEN MADE
TO THE ONGOING CRITICAL AREA...WITH NO CHANGES MADE TO THE ONGOING
ELEVATED AREA SURROUNDING THE CRITICAL AREA. ACCOMPANYING FORECAST
CONDITIONS WITHIN THE CRITICAL AREA AND ELEVATED AREA AS DESCRIBED
IN THE PREVIOUS FORECAST ARE UNCHANGED.
...HILLS SURROUNDING SAN FRANCISCO BAY AREA...
NO CHANGES HAVE BEEN MADE TO THE ONGOING FORECAST.
..COHEN.. 12/29/2013
.PREV DISCUSSION... /ISSUED 0355 AM CST SUN DEC 29 2013/
...SYNOPSIS...
AN UPPER RIDGE WILL CONTINUE TO BUILD INTO THE WEST TODAY...AS A
LARGE-SCALE UPPER TROUGH CONSOLIDATES OVER THE CNTRL/ERN CONUS. SFC
HIGH PRESSURE WILL BE IN PLACE OVER THE GREAT BASIN...GENERATING A
MODERATE TO LOCALLY STRONG OFFSHORE WIND EVENT OVER PARTS OF SRN CA
THAT WILL RESULT IN A THREAT OF CRITICAL FIRE WEATHER CONDITIONS.
...COASTAL MOUNTAINS/FOOTHILLS OF SRN CA...
CRITICAL CONDITIONS ARE EXPECTED OVER PARTS OF VENTURA AND LOS
ANGELES FOR SEVERAL HOURS LATER THIS MORNING INTO THE AFTERNOON.
OFFSHORE WINDS ARE CURRENTLY INCREASING ACROSS HIGHER ELEVATIONS AND
CRITICALLY STRONG SUSTAINED WINDS OF 20 MPH ARE EXPECTED TO DEVELOP
ACROSS PARTS OF VENTURA AND LOS ANGELES COUNTIES BY 12-15Z THIS
MORNING AS THE PRESSURE GRADIENT INCREASES. LATEST HI-RES GUIDANCE
CONTINUES TO DEPICT SUSTAINED WINDS PEAKING AT 20-30 MPH ACROSS THE
CRITICAL AREA EARLY THIS AFTERNOON...WITH GUSTS OF 50-60 MPH
POSSIBLE. RH SHOULD BECOME CRITICALLY LOW BY LATE MORNING...WITH
MINIMUM RH VALUES OF 8-15 PERCENT EXPECTED ACROSS THE CRITICAL AREA.
SURROUNDING THE CRITICAL AREA...WIND SPEEDS ARE EXPECTED TO BE
SOMEWHAT LESS...BUT MINIMUM RH BELOW 15 PERCENT AND SUSTAINED WINDS
OF 15-20 MPH WILL SUPPORT ELEVATED TO LOCALLY CRITICAL CONDITIONS.
LATE THIS AFTERNOON INTO TONIGHT...THE PRESSURE GRADIENT IS EXPECTED
TO WEAKEN AND WINDS WILL LARGELY FALL BELOW CRITICAL INTENSITY BY
THIS EVENING. HOWEVER...ELEVATED CONDITIONS WILL PERSIST THROUGH
MOST OF THE NIGHT GIVEN POOR OVERNIGHT RH RECOVERY.
...HILLS SURROUNDING SAN FRANCISCO BAY AREA...
LOCALLY ELEVATED CONDITIONS ARE ONGOING AS OF 09Z THIS MORNING IN
THE HIGHER ELEVATIONS NORTH AND EAST OF THE SF BAY AREA...WITH
SUSTAINED WINDS OF 15-25 MPH AND RH VALUES 20-30 PERCENT AMIDST DRY
FUELS. THESE CONDITIONS WILL LIKELY PERSIST INTO LATE MORNING OR
EARLY AFTERNOON BEFORE WINDS WEAKEN. GIVEN THE ANTICIPATED LIMITED
SPATIAL EXTENT AND DURATION /AFTER 12Z/ OF THE THREAT...NO ELEVATED
AREA HAS BEEN DELINEATED.
...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...