087  
FXUS65 KMSO 192048  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
248 PM MDT SUN MAY 19 2019  
   
DISCUSSION
 
BREEZY NORTHEAST TO EAST WINDS CONTINUE TO DEVELOP  
THIS AFTERNOON AS WESTERN MONTANA AND CENTRAL IDAHO SIT BETWEEN  
HIGH PRESSURE TO THE NORTHEAST AND LOW PRESSURE TO THE SOUTHWEST  
WEST. WINDS ARE EXPECTED TO PEAK THIS EVENING, THOUGH EASTERLY  
WINDS WILL CONTINUE INTO MONDAY, AND LIKELY THROUGH A GOOD CHUNK  
OF THE UPCOMING WEEK. WINDS WILL BE MOST NOTICEABLE ACROSS  
WESTERN MONTANA, AND COULD CAUSE INCREASED CHOP ON FLATHEAD LAKE  
THROUGH THIS EVENING.  
 
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND  
EVENING ACROSS PRIMARILY NORTH CENTRAL IDAHO (SOUTH OF HIGHWAY 12)  
AND LEMHI COUNTY. MAIN THREATS WILL BE BRIEF HEAVY RAIN.  
 
WESTERN MONTANA AND NORTHCENTRAL IDAHO WILL REMAIN UNDER THE  
INFLUENCE OF AN UPPER LEVEL TROUGH OF LOW PRESSURE FOR MUCH OF THE  
WEEK. THE BEST CHANCES OF PRECIPITATION WILL CONTINUE TO EXIST  
ACROSS NORTH CENTRAL IDAHO AND LEMHI COUNTY FOR MONDAY AND TUESDAY,  
WHILE WESTERN MONTANA WILL GENERALLY BE DRIER DUE TO THE DRYING  
EASTERLY WINDS. FORECAST MODELS ARE SHOWING A MID LEVEL  
CIRCULATION MOVING INTO SOUTHERN IDAHO COUNTY MONDAY NIGHT INTO  
TUESDAY MORNING, WHICH COULD BRING A QUICK BURST OF MODERATE TO  
HEAVY RAIN, PRIMARILY FOR LOCATIONS FROM GRANGEVILLE AND  
SOUTHWARD. SMALL STREAMS AND RIVERS WILL CONTINUE TO RUN HIGH IN  
THIS AREA, BUT FLOODING IS NOT ANTICIPATED AT THIS TIME.  
 
TUESDAY NIGHT INTO WEDNESDAY, A LOW PRESSURE SYSTEM WILL MEANDER  
TO OUR SOUTH AND EAST, SPREADING PRECIPITATION INTO MAINLY WESTERN  
MONTANA, PARTICULARLY ALONG THE CONTINENTAL DIVIDE. SNOW LEVELS  
WILL LOWER ENOUGH THAT HIGH ELEVATION VALLEYS AND MOUNTAIN PASSES  
(GEORGETOWN LAKE, MACDONALD PASS, HOMESTAKE PASS, AND POSSIBLY  
BUTTE) COULD SEE A PERIOD OF SNOW WEDNESDAY MORNING.  
 
COOL AND SHOWERY CONDITIONS WILL CONTINUE PAST WEDNESDAY, BUT  
FORECAST MODELS DO INDICATE A GRADUAL WARMING WILL OCCUR INTO  
MEMORIAL DAY WEEKEND.  
 

 
   
AVIATION
 
A STRENGTHENING EAST TO NORTHEASTERLY GRADIENT WILL  
KEEP BLUSTERY WINDS THE PREDOMINANT WEATHER FEATURE TODAY. GUSTY  
WINDS WILL LAST WELL INTO THE OVERNIGHT HOURS, AND LIKELY THROUGH  
MONDAY MORNING AS WELL. SHOWERS AND AN ISOLATED CHANCE FOR  
THUNDERSTORMS WILL EXIST ACROSS SOUTH CENTRAL IDAHO, HOWEVER KSMN  
AND KBTM SHOULDN'T BE AFFECTED BY CONVECTIVE ACTIVITY. AT THE  
MOST, LIGHT RAIN MAY OCCUR FOR THESE TWO TERMINALS, WHILE THE  
REST OF THE NORTHERN ROCKIES REMAINS CLOUDY BUT DRY.  
 

 
   
MSO WATCHES/WARNINGS/ADVISORIES
 
 
MT...LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FLATHEAD/MISSION  
VALLEYS.  
 
ID...NONE.  

 
 

 
 
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