Fire Weather Outlook Discussion
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000
FNUS22 KWNS 041758
FWDDY2

DAY 2 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 PM CDT FRI SEP 04 2015

VALID 051200Z - 061200Z

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

ONLY A SLIGHT MODIFICATION WAS MADE TO THE CRITICAL RISK AREA ACROSS
W-CNTRL UT AND FAR E-CNTRL NV...TO ACCOUNT FOR HIGHEST CONFIDENCE
AREA IN STRONG PRE-FRONTAL SWLY WIND SPEEDS /SUSTAINED AT 20-25
MPH/. OTHERWISE...THE ELEVATED RISK AREA HAS BEEN LEFT INTACT.
STRONG SWLY WINDS ARE LIKELY TO EXTEND INTO PORTIONS OF WRN/CNTRL
WY...BUT IT IS UNCERTAIN IF RH WILL GET LOW ENOUGH TO JUSTIFY
INCLUSION IN AN ELEVATED RISK AREA. HOWEVER...LOCALIZED POCKETS OF
LOWER RH ARE POSSIBLE...PARTICULARLY WHERE DOWNSLOPE-ENHANCED DRYING
MAY OCCUR. LIGHT PRECIPITATION MAY ALSO OCCUR OVER THE REGION THIS
EVENING AND OVERNIGHT...ALTHOUGH AMOUNTS ARE FORECAST TO GENERALLY
REMAIN BELOW ONE TENTH OF AN INCH.

..ROGERS.. 09/04/2015

.PREV DISCUSSION... /ISSUED 0325 AM CDT FRI SEP 04 2015/

...SYNOPSIS...
AS A SHARP MID/UPPER-LEVEL IMPULSE TRANSLATES EWD ACROSS THE GREAT
BASIN...THE LARGER-SCALE WRN-CONUS TROUGH WILL DE-AMPLIFY SOME AND
PROGRESS SLIGHTLY EWD. MEANWHILE...GENERALLY ANTICYCLONIC FLOW WILL
STRETCH FROM THE SRN PLAINS NEWD TO PORTIONS OF THE MIDWEST. AT THE
SFC...A COLD FRONT WILL PROGRESS SEWD ACROSS THE NRN TWO-THIRDS OF
THE GREAT BASIN. FARTHER EAST...CYCLOGENESIS WILL OCCUR OVER THE NRN
PLAINS.

...PORTIONS OF THE GREAT BASIN...
A TIGHTENING MID-LEVEL HEIGHT GRADIENT OVER THE REGION WILL YIELD A
CONTINUATION OF STRONG SWLY WINDS ALOFT. AS SUCH...DIURNAL MIXING
WILL FAVOR SUSTAINED SFC WINDS AROUND 20-35 MPH FROM SRN NV NEWD
INTO WY AHEAD OF AN APPROACHING COLD FRONT. WITH A DRY AIR MASS
PERSISTING OVER THE REGION...DIURNAL MIXING WILL LIKELY YIELD MIN RH
VALUES AROUND 10-15 PERCENT ACROSS PORTIONS OF ERN NV/WRN UT.
HIGHEST CONFIDENCE IN AN ADEQUATE OVERLAP OF THESE METEOROLOGICAL
CONDITIONS WITH DRY FUELS CURRENTLY EXISTS OVER W-CNTRL UT. THUS...A
CRITICAL DESIGNATION HAS BEEN INTRODUCED HERE. ACROSS ERN NV/NWRN
UT...TIMING OF THE COLD-FRONT PASSAGE AROUND PEAK HEATING WILL
LIKELY RESULT IN WEAKER/VEERING WINDS AROUND THE TIME OF MIN RH
VALUES. THEREFORE...THESE AREAS ARE INCLUDED IN ONLY AN ELEVATED
DESIGNATION. HOWEVER...EXPANSION OF THE CRITICAL AREA /ESPECIALLY
OVER NWRN UT AND NERN NV/ MAY BE REQUIRED IN LATER
UPDATES...CONTINGENT UPON INCREASING CONFIDENCE IN THE OVERLAP OF
STRONG WLY POST-FRONTAL WINDS AND CRITICALLY LOW RH VALUES.

STRONG SWLY SFC FLOW WILL EXIST OVER MUCH OF SWRN/CNTRL WY AS WELL.
DOWNSLOPE TRAJECTORIES IN THE LEE OF THE WIND RIVER RANGE WILL
LIKELY FAVOR AT LEAST A FEW AREAS OF RH VALUES AROUND 15-20 PERCENT.
SUCH METEOROLOGICAL CONDITIONS ARE CONSISTENT WITH AT LEAST AN
ELEVATED FIRE-WEATHER THREAT. HOWEVER...FUEL GUIDANCE AND MRMS 7-DAY
QPE OVER THE REGION SUGGEST FUELS MAY NOT BE SUFFICIENTLY RECEPTIVE
TO JUSTIFY SUCH A DESIGNATION. NONETHELESS...ONE MAY BECOME
NECESSARY IN FUTURE UPDATES...ESPECIALLY CONSIDERING THE FORECAST
STRENGTH OF SWLY WINDS.

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



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