Fire Weather Outlook Discussion
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000
FNUS21 KWNS 050817
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0316 AM CDT SAT SEP 05 2015

VALID 051200Z - 061200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF W-CNTRL UT AND FAR
E-CNTRL NV...

...SYNOPSIS...
A SHARP IMPULSE ALOFT WILL TRANSLATE E/NEWD FROM THE NRN SIERRA
NEVADA TO THE NRN ROCKIES...WITH THE ASSOCIATED LARGER-SCALE TROUGH
SLOWLY PROGRESSING EWD THROUGH THE PERIOD. ELSEWHERE...BROAD RIDGING
ACROSS THE ERN CONUS WILL GRADUALLY DE-AMPLIFY. AT THE SFC...A COLD
FRONT WILL MOVE EWD ACROSS THE NERN GREAT BASIN AND PORTIONS OF THE
NRN ROCKIES...WHILE LOW PRESSURE MIGRATES EWD OVER THE NRN PLAINS.

...PORTIONS OF THE GREAT BASIN...
AS THE AFOREMENTIONED IMPULSE EJECTS EWD ACROSS THE NRN GREAT
BASIN...THE TIGHTENING HEIGHT GRADIENT ALOFT WILL MAINTAIN A
CORRIDOR OF ENHANCED SWLY FLOW FROM THE LOWER CO RIVER VALLEY NEWD
TO WY. WITH THE ONSET OF DIURNAL MIXING...EFFICIENT VERTICAL
TRANSFER OF THIS HIGHER-MOMENTUM AIR SHOULD PROMOTE SUSTAINED SFC
WINDS AROUND 15-30 MPH FROM SRN NV N/NEWD TO CNTRL UT.
ADDITIONALLY...THE COLD FRONT PASSAGE ACROSS NERN NV/NWRN UT WILL
YIELD SUSTAINED WLY WINDS UPWARDS OF 20 MPH IN THIS AREA BY
AFTERNOON. MOREOVER...A DRY AIR MASS /CHARACTERIZED BY PWAT VALUES
AROUND 0.2-0.5 INCHES/ WILL REMAIN SITUATED OVER MUCH OF THE GREAT
BASIN...FAVORING MIN RH VALUES AROUND 8-15 PERCENT. THE MOST LIKELY
AREA FOR AN OVERLAP OF CRITICALLY LOW RH VALUES WITH THE STRONGEST
FLOW /I.E. SUSTAINED WINDS OVER 20 MPH/ EXISTS OVER PARTS OF FAR ERN
NV/W-CNTRL UT. THUS...THE CRITICAL DESIGNATION IS MAINTAINED HERE.
AN ELEVATED DESIGNATION SURROUNDS THIS AREA...AS FLOW WILL BE
SLIGHTLY WEAKER BUT STILL SUFFICIENT FOR AN ENHANCED FIRE-WX THREAT.

...PORTIONS OF CNTRL WY...
THE STRONG/DRY SWLY FLOW REGIME WILL EXTEND NEWD ACROSS WY DURING
THE PERIOD. DOWNSLOPE TRAJECTORIES WILL AUGMENT DIURNAL MIXING SUCH
THAT SFC TEMPS WILL LIKELY CLIMB WELL INTO THE 80S IN A FEW SPOTS.
CONCURRENTLY...RH VALUES WILL FALL TO AROUND 15-20 PERCENT /WITH
ISOLATED INSTANCES OF 12-15 PERCENT/ ACROSS THIS AREA. SUSTAINED
WINDS AROUND 25-35 MPH /WITH HIGHER GUSTS/ WILL COMBINE WITH THESE
DRY CONDITIONS AND POCKETS OF RECEPTIVE FUELS TO FOSTER AN ELEVATED
FIRE-WX THREAT. ADDITIONALLY...LOCALLY CRITICAL CONDITIONS
/ESPECIALLY IN THE LEE OF THE WIND RIVER RANGE/ ARE LIKELY...AND A
SMALL CRITICAL DESIGNATION MAY BE WARRANTED WITH THE D1-FORECAST
UPDATE.

..PICCA.. 09/05/2015

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




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