Fire Weather Outlook Discussion
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FNUS21 KWNS 041522
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1021 AM CDT FRI SEP 04 2015

VALID 041700Z - 051200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF ERN/SRN NV AND WRN
UT...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NWRN NV...

MINIMAL CHANGES WERE MADE TO THE PREVIOUS FIRE WEATHER OUTLOOK.
LATEST OBSERVATIONAL/MODEL TRENDS CONTINUE TO HIGHLIGHT TWO SEPARATE
CORRIDORS FOR STRONG WINDS AS A TROUGH SLOWLY DIGS SWD OVER THE PAC
NW COAST. 12Z SOUNDINGS FROM VEF AND REV SHOWED STEEP LOW-LEVEL
LAPSE RATES ALREADY IN PLACE...WITH 20-30 KT OF FLOW OBSERVED ABOVE
1 KM AGL. FURTHER HEATING/MIXING SHOULD PROMOTE WIDESPREAD SUSTAINED
WIND SPEEDS OF 20-25 MPH...WITH THE FOCUS FOR CRITICAL CONDITIONS
REMAINING ACROSS PORTIONS OF SRN/ERN NV AND NWRN UT.

CRITICAL FIRE WEATHER CONDITIONS ALSO APPEAR LIKELY ACROSS NWRN
NV...WHERE STRONG DOWNSLOPE EFFECTS WILL COMBINE WITH STRONG FLOW
ALOFT AND BOUNDARY-LAYER MIXING TO SUPPORT W-SWLY WINDS OF 25-35 MPH
AMIDST RH VALUES APPROACHING 10 PERCENT THIS AFTERNOON INTO THE
EVENING.

..ROGERS.. 09/04/2015

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

...SYNOPSIS...
A MID/UPPER-LEVEL TROUGH /WITH SEVERAL EMBEDDED VORTICITY MAXIMA/
WILL BE ESTABLISHED OVER MUCH OF THE WEST COAST/NRN ROCKIES/GREAT
BASIN TODAY. ELSEWHERE...BROAD RIDGING WILL BE SITUATED OVER MOST OF
THE CNTRL/ERN CONUS. THE ASSOCIATED SFC RESPONSE WILL FEATURE A
STATIONARY FRONT STRETCHING FROM SWRN MT SWWD TOWARDS NWRN
NV...WHILE CYCLOGENESIS OCCURS OVER NERN NV/FAR SRN ID.

...PORTIONS OF THE GREAT BASIN...
TWO PRIMARY AREAS OF ENHANCED FIRE-WEATHER CONCERN WILL EXIST TODAY.
THE FIRST WILL STRETCH FROM SRN NV NEWD INTO NWRN UT...AS A BELT OF
STRONG 700-MB FLOW PERSISTS OVER THIS CORRIDOR. WITH THE ONSET OF
DIURNAL MIXING...VERTICAL TRANSFER OF THIS HIGHER-MOMENTUM AIR WILL
YIELD SWLY WINDS AROUND 25-35 MPH SUSTAINED /WITH HIGHER GUSTS/. 00Z
RAOBS DEPICT A DRY AIR MASS /CHARACTERIZED BY PWATS AROUND 0.3-0.5
INCHES/ OVER MUCH OF THE REGION...WHICH WILL FAVOR A RAPID REDUCTION
OF SFC RH VALUES BELOW 15 PERCENT AS THE AFOREMENTIONED MIXING
ENSUES. WITH DRY FUELS STILL PRESENT...THESE METEOROLOGICAL
CONDITIONS WILL SUPPORT A CRITICAL FIRE-WX THREAT.

THE SECOND FOCUSED AREA OF CONCERN WILL EXIST OVER NWRN NV. AS AN
EMBEDDED IMPULSE ALOFT TRANSLATES EWD OVER THE NRN SIERRA
NEVADA...ENHANCED WLY FLOW WILL PROMOTE GUSTY DOWNSLOPE WINDS IN THE
LEE OF THE MOUNTAINS. RH VALUES ARE LIKELY TO FALL TO AROUND 10-15
PERCENT...WHICH IN COMBINATION WITH DRY FUELS...WILL MAINTAIN A
CRITICAL THREAT HERE AS WELL.

SURROUNDING THE CRITICAL DESIGNATIONS...WEAKER WINDS/HIGHER RH
VALUES WILL TEMPER FIRE-WX CONCERNS SOME...BUT SHOULD STILL SUPPORT
AN ELEVATED THREAT. THUS...THE PREVIOUS DELINEATION REMAINS
GENERALLY UNCHANGED.

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



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