940  
FXUS65 KMSO 090857  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
257 AM MDT SUN AUG 9 2020  
   
DISCUSSION
 
THE NORTHERN ROCKIES WILL REMAIN UNDER A DRY  
WESTERLY FLOW THROUGH AT LEAST TUESDAY. A LONGWAVE TROUGH WILL  
REMAIN ANCHORED ACROSS ALASKA AND PORTIONS OF WESTERN CANADA TODAY  
THROUGH EARLY NEXT WEEK. SHORTWAVE TROUGHS WILL PROGRESS EASTWARD  
ACROSS BRITISH COLUMBIA AND ALBERTA MONDAY INTO TUESDAY. THIS  
WILL RESULT IN THE FOUR CORNERS HIGH REMAINING SUPPRESSED ACROSS  
THE DESERT SOUTHWEST, LEAVING THE WESTERN U.S. IN A DRY WESTERLY  
FLOW. TEMPERATURES WILL MODERATE BACK TO SEASONAL AVERAGES BY  
TUESDAY, WITH HIGHS WARMING INTO THE MID TO UPPER 80S ACROSS  
MONTANA VALLEY LOCATIONS AND INTO THE 90S ACROSS LOWER ELEVATIONS  
OF CENTRAL IDAHO.  
 
A DRY COLD FRONT ASSOCIATED WITH A SHORTWAVE TROUGH MOVING  
EASTWARD ACROSS ALBERTA WILL MOVE ACROSS THE NORTHERN ROCKIES  
TUESDAY INTO WEDNESDAY MORNING. THE PRIMARY CONCERN TUESDAY IS THE  
POTENTIAL FOR AREAS OF CRITICAL FIRE WEATHER CONDITIONS,  
PARTICULARLY ACROSS SOUTHWEST MONTANA, DUE TO THE COMBINATION OF  
LOW HUMIDITY AND GUSTY WINDS WITH THE FRONT.  
 
MODEL ENSEMBLE GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THE  
EVOLUTION OF THE WEATHER PATTERN WEDNESDAY THROUGH FRIDAY NEXT  
WEEK. A SHORTWAVE TROUGH WILL DIG SOUTHWARD ACROSS BRITISH  
COLUMBIA AND WILL MOVE EASTWARD ACROSS ALBERTA AND NORTHWEST  
MONTANA. ENSEMBLE GUIDANCE HAVE BACKED OFF ON THE DEPICTION OF A  
DEEPER SHORTWAVE TROUGH DIGGING SOUTHWARD INTO WESTERN MONTANA.  
INSTEAD, GUIDANCE IS FAVORING THE BULK OF PRECIPITATION AND COOLER  
TEMPERATURES STAYING NORTHWARD IN CANADIAN. NONETHELESS,  
TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL DURING THIS TIME  
PERIOD; HOWEVER, A WIDESPREAD PRECIPITATION EVENT ACROSS THE  
NORTHERN ROCKIES LOOKS FAR LESS LIKELY.  
 

 
   
AVIATION
 
VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS THE  
NORTHERN ROCKIES TODAY. BREEZY WEST TO NORTHWESTERLY WINDS WILL  
DEVELOP THIS AFTERNOON WITH GUSTS UP TO 20 KNOTS BEING COMMON AS  
AN UPPER-LEVEL JET NOSES INTO NORTHWEST MONTANA NEAR THE  
CONTINENTAL DIVIDE. SCATTERED FAIR WEATHER CUMULUS CLOUDS ARE  
EXPECTED ACROSS WESTERN MONTANA THIS AFTERNOON. SKIES WILL  
GRADUALLY BEGIN TO CLEAR OUT LATER THIS EVENING AS DRIER MID-LEVEL  
AIR MOVES INTO THE REGION.  
 

 
   
MSO WATCHES/WARNINGS/ADVISORIES
 
 
MT...NONE.  
ID...NONE.  

 
 

 
 
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