Fire Weather Outlook Discussion
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FNUS21 KWNS 241627
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CDT SAT SEP 24 2016

VALID 241700Z - 251200Z

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

...MOUNTAINS AND ADJACENT FOOTHILLS OF SOUTHERN CA...
RECENT SURFACE ANALYSIS REVEALED OFFSHORE GRADIENTS OF 7.5 MB FROM
LAX-TPH AND 3 MB LAX-DAG. GUSTS OVER 20 MPH ARE STILL OCCURRING AT
SOME OF THE HIGHER ELEVATIONS SITES WITH LOCALIZED GUSTY CONDITIONS
EXPECTED TO PERSIST THROUGH THE LATE AFTERNOON. WINDS WILL PICK UP
AGAIN TONIGHT WITH SUSTAINED SPEEDS ABOVE 25 MPH AND GUSTS OVER 45
MPH POSSIBLE. GIVEN THE ANTICIPATED POOR RH RECOVERY AND PERSISTENT
WARM TEMPERATURES TONIGHT...WIDESPREAD CRITICAL FIRE WEATHER
CONDITIONS ARE STILL LIKELY ACROSS MUCH OF THE REGION. NO CHANGES
ARE NEEDED TO THE ONGOING FORECAST.

...NORTHERN CA -- INCLUDING WRN SLOPES OF THE SIERRA...SACRAMENTO
VALLEY AND NRN COASTAL RANGES...
LOCALLY CRITICAL CONDITIONS ARE POSSIBLE ACROSS PORTIONS OF THE
SACRAMENTO VALLEY THIS AFTERNOON WHERE TEMPERATURES WILL BE IN THE
90S AND MIN RH VALUES IN THE TEENS. NLY WINDS WILL LIKELY STAY BELOW
20 MPH ACROSS MUCH OF THE REGION BUT LOCALIZED AREAS MAY EXPERIENCE
WINDS GREATER THAN 20 MPH FOR AN HOUR OR TWO. GIVEN THESE EXPECTED
CONDITIONS...ADDED THE SACRAMENTO VALLEY TO THE ELEVATED DELINEATION
ACROSS THE REGION. HIGHER ELEVATION AREAS ARE MORE LIKELY TO
EXPERIENCE STRONGER WINDS AND LOWER RH VALUES TONIGHT AS POOR RH
RECOVERY OCCURS AMIDST A MODEST OFFSHORE GRADIENT AND NO CHANGE TO
THE PREVIOUS FORECAST WAS NEEDED IN THESE AREAS.

..MOSIER.. 09/24/2016

.PREV DISCUSSION... /ISSUED 0236 AM CDT SAT SEP 24 2016/

...SYNOPSIS...
A FAIRLY AMPLIFIED MID/UPPER-LEVEL TROUGH WILL EXTEND FROM NORTHERN
MEXICO NORTH/NORTHEASTWARD TO THE CANADIAN PRAIRIES...AS ONE
EMBEDDED LOW LIFTS NORTHEAST ACROSS THE DAKOTAS...AND ANOTHER
DEVELOPS OVER THE DESERT SOUTHWEST LATE IN THE PERIOD.
MEANWHILE...UPSTREAM RIDGING WILL BUILD OVER CALIFORNIA AND PARTS OF
THE PACIFIC NORTHWEST...RESULTING IN A TIGHTENING HEIGHT GRADIENT
AND INCREASING NORTHERLY FLOW ALOFT FROM THE NORTHERN ROCKIES TO THE
DESERT SOUTHWEST.

...PORTIONS OF SOUTHERN CALIFORNIA...
WITH AN INVERTED SFC TROUGH SITUATED ALONG/NEAR THE CA COAST...A
BUILDING RIDGE ACROSS THE GREAT BASIN WILL TIGHTEN THE PRESSURE
GRADIENT...FAVORING INCREASING OFFSHORE FLOW. ELEVATED/LOCALLY
CRITICAL CONCERNS SHOULD BE ONGOING ACROSS HIGHER
ELEVATIONS/TERRAIN-FAVORED LOCATIONS THIS MORNING...WITH NORTHEAST
WINDS AROUND 15-25 MPH SUSTAINED AND POOR RH RECOVERIES /GENERALLY
AROUND 20-30 PERCENT/. WIND SPEEDS MAY EXPERIENCE SOME DIURNAL
WEAKENING...BUT TERRAIN-FAVORED LOCATIONS MAY MAINTAIN SUSTAINED
WINDS OVER 20 MPH...AS MID-LEVEL FLOW VEERS FROM THE NORTH TO
NORTHEAST -- INCREASING THE OFFSHORE COMPONENT. MEANWHILE...RH
VALUES WILL FALL TO AROUND 8-20 PERCENT. AS SUCH...POCKETS OF
CRITICAL CONCERNS MAY CONTINUE THROUGH THE DAY.

THE GREATEST POTENTIAL FOR RAPID FIRE SPREAD ARRIVES LATE TONIGHT AS
THE OFFSHORE PRESSURE GRADIENT NOCTURNALLY STRENGTHENS...SUPPORTING
SUSTAINED NORTHEAST WINDS AROUND 20-30 MPH /WITH GUSTS UP TO 45-55
MPH/. RH RECOVERIES WILL BE POOR ONCE AGAIN...SUCH THAT MORE
WIDESPREAD CRITICAL CONCERNS ARE ANTICIPATED TONIGHT.

...PORTIONS OF NORTHERN CALIFORNIA...
ELEVATED/LOCALLY CRITICAL CONDITIONS ARE ANTICIPATED LATE TONIGHT
ACROSS THE WESTERN SLOPES OF THE SIERRA NEVADA...AS WELL AS NEAR
COASTAL RANGES OF NORTHERN CALIFORNIA. INCREASING OFFSHORE FLOW
/WITH SUSTAINED WINDS AROUND 15-25 MPH/...POOR RH RECOVERIES...AND
DRY FUELS WILL ENHANCE THE THREAT FOR RAPID FIRE SPREAD...WITH THE
GREATEST POTENTIAL VERY LATE IN THE PERIOD WHEN EASTERLY DOWNSLOPE
FLOW MAXIMIZES.

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...

$$


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