182  
FNUS22 KWNS 201855  
FWDDY2  
 
DAY 2 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0154 PM CDT THU JUL 20 2017  
 
VALID 211200Z - 221200Z  
 
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL  
MONTANA...  
 
CONFIDENCE IN SUFFICIENTLY STRONG WINDS HAS INCREASED ENOUGH TO  
INTRODUCE A CRITICAL AREA FOR PORTIONS OF MONTANA FRIDAY. A MODESTLY  
ENHANCED SURFACE PRESSURE GRADIENT WILL COMBINE WITH DOWNWARD MIXING  
OF STRONGER FLOW ALOFT TO SUPPORT SUSTAINED WESTERLY WINDS AROUND  
20-25 MPH DURING THE DAY. ADDITIONALLY, DIURNAL MIXING WILL  
CONTRIBUTE TO RH VALUES AROUND 10-20%. AS FUELS SHOULD REMAIN QUITE  
DRY ACROSS MUCH OF THE REGION, CRITICAL FIRE-WEATHER CONCERNS ARE  
LIKELY TO MATERIALIZE. ELSEWHERE, NO CHANGES ARE MADE TO THE ONGOING  
FORECAST.  
 
..PICCA.. 07/20/2017  
   
PREV DISCUSSION
 
/ISSUED 0210 AM CDT THU JUL 20 2017/  
   
..SYNOPSIS
 
 
AN UPPER TROUGH/LOW OVER AB/SK FRIDAY MORNING WILL CONTINUE MOVING  
EASTWARD ACROSS THE CANADIAN PRAIRIE PROVINCES THROUGH THE PERIOD.  
AROUND 35-45 KT OF MID-LEVEL WESTERLIES ATTENDANT TO THIS TROUGH  
WILL OVERSPREAD MUCH OF MT AND VICINITY BY FRIDAY AFTERNOON. AT THE  
SURFACE, AN AREA OF LOW PRESSURE ACROSS THE NORTHERN HIGH PLAINS  
SHOULD DEVELOP SLOWLY EASTWARD INTO THE DAKOTAS THROUGH FRIDAY  
EVENING. A TRAILING COLD FRONT SHOULD MOVE SOUTHEASTWARD ACROSS THE  
NORTHERN/CENTRAL HIGH PLAINS.  
 
...PORTIONS OF THE NORTHERN GREAT BASIN INTO THE NORTHERN  
ROCKIES/HIGH PLAINS...  
STRONG/GUSTY WESTERLY WINDS OF 15-20 MPH ARE EXPECTED TO DEVELOP  
BEHIND THE PREVIOUSLY MENTIONED SURFACE COLD FRONT FRIDAY AFTERNOON  
ALONG AND EAST OF THE ROCKIES. DIURNAL HEATING AND A DOWNSLOPE  
COMPONENT TO THESE WINDS WILL LIKELY WARM AND DRY THE BOUNDARY  
LAYER, AND RH VALUES OF 7-20% SHOULD DEVELOP ACROSS MUCH OF  
CENTRAL/EASTERN MT BY PEAK HEATING. AN ELEVATED FIRE WEATHER AREA  
HAS BEEN MADE FOR PARTS OF THE NORTHERN HIGH PLAINS TO ACCOUNT FOR  
THIS THREAT, AND SOME POTENTIAL EXISTS FOR AN UPGRADE TO CRITICAL  
DELINEATION WHERE SUSTAINED WINDS MAY EXCEED 20 MPH. HOWEVER,  
FORECAST WINDS IN SHORT-TERM GUIDANCE REMAIN TOO MARGINAL TO  
DELINEATE A CRITICAL AREA AT THIS TIME.  
 
A SMALL CORRIDOR OF ELEVATED CONDITIONS IS ALSO FORECAST TO OCCUR  
ACROSS PART OF THE SNAKE RIVER VALLEY IN SOUTHERN ID FRIDAY  
AFTERNOON/EVENING. HERE, SUSTAINED WINDS OF 15-20 MPH SHOULD COMBINE  
WITH RH VALUES GENERALLY BETWEEN 7-15%. THE LACK OF STRONGER  
FORECAST WINDS PRECLUDES A CRITICAL DESIGNATION.  
   
..PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT
 
 

 
 
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