460  
FXUS65 KMSO 221040  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
340 AM MST WED NOV 22 2017  
   
DISCUSSION
 
THE NEXT WAVE OF MODERATE PRECIPITATION WILL  
CONTINUE TO MOVE THROUGH IDAHO AND WESTERN MONTANA THIS MORNING.  
RAIN WILL BECOME LESS COMMON IN THE VALLEYS BY THE AFTERNOON, BUT  
REMAIN IN THE MOUNTAINS.  
 
RAIN SHOWERS WILL BE AROUND FOR THE BEGINNING OF THANKSGIVING  
DAY, BUT THE MAIN STORY REMAINS THE DAMAGING WIND THREAT. THE  
STRONG WIND SCENARIO THAT MODEL GUIDANCE ARE DEPICTING HAS BEEN  
VERY CONSISTENT, SO STRONG WINDS IN THE TERRAIN OF 50 MPH AND  
HIGHER SHOULD BE PLANNED FOR. AREAS THAT WE ARE CONCERNED WITH  
EXPERIENCING STRONG WINDS INCLUDE THE FLATHEAD VALLEY SOUTH TO  
MISSOULA, THROUGH THE BITTERROOT VALLEY, AND THE VALLEYS OF  
SOUTHWESTERN MONTANA, SO THE HIGH WIND WATCH HAS NOT BEEN  
CHANGED. THERE IS STILL A CHANCE THAT A FEW LOCATIONS IN LINCOLN  
COUNTY MAY SEE GUSTS NEAR 50 MPH, BUT CONFIDENCE IS NOT AS HIGH. THE  
WINDS IN THE FORECAST HAVE BEEN INCREASED IN THE LATEST UPDATE  
SINCE CONFIDENCE CONTINUES TO INCREASE. ONE ASPECT OF THIS  
THURSDAY WEATHER PATTERN THAT IS INTERESTING IS THAT THE UPPER JET  
WILL BE PARALLEL TO THE COLD FRONT WHICH IS USUALLY A GOOD SET UP  
FOR PRECIPITATION, SO MODERATE TO EVEN HEAVY RAIN MAY ACCOMPANY  
THE STRONG WINDS. SHOWERS MAY ORGANIZE INTO A LINE ALONG THE  
FRONT, AND HIGH RESOLUTION MODEL GUIDANCE ARE ALREADY SHOWING  
INDICATIONS OF A STRONG LINE OF SHOWERS DURING THE EVENING.  
FEATURES LIKE THIS ARE NOTORIOUS STRONG WIND PRODUCERS.  
 
SNOW LEVELS WILL LOWER BEHIND THE COLD FRONT THURSDAY NIGHT SO  
SNOW IS LIKELY TO RETURN TO THE HIGH TERRAIN AND THERE MAY EVEN BE  
SOME SNOW AT LOWER ELEVATIONS.  
 
THE NEXT IMPACTFUL WEATHER SYSTEM LOOKS TO ARRIVE TO NORTH-CENTRAL  
IDAHO AND WESTERN MONTANA ON SUNDAY. PRECIPITATION IS FORECAST TO  
START AS RAIN DURING SUNDAY AND CHANGE TO SNOW AT MOST ELEVATIONS  
FOR MONDAY MORNING. THIS WEATHER SYSTEM IS MUCH COLDER THAN WHAT  
HAS BEEN OCCURRING RECENTLY, SO TRAVEL IMPACTS FROM SNOW AND/OR  
ICE ARE OF CONCERN. SNOW CHANCES WILL LINGER THROUGH TUESDAY.  
 

 
   
AVIATION
 
VISIBILITIES AND CEILINGS HAVE BEEN QUITE VARIABLE AT  
VALLEY LOCATIONS OVERNIGHT WITH NEARLY SATURATED SURFACE  
CONDITIONS DUE TO A STRONG PLUME OF MOISTURE MOVING THROUGH THE  
REGION. THESE VARIABLE CONDITIONS WILL LAST THROUGH MUCH OF THE  
MORNING WITH A MIX OF FOG, RAIN, AND LOW CEILINGS. PRECIPITATION  
WILL TAPER OFF AND MIXING WILL INCREASE AT LOW ELEVATIONS SO  
IMPROVEMENTS ARE EXPECTED BY THIS AFTERNOON, THOUGH A STRATUS DECK  
MAY REMAIN. THE HIGHER TERRAIN HAS BEEN AND WILL CONTINUE TO BE  
OBSCURED WITH MOISTURE VIA MOIST SOUTHWESTERLY FLOW TODAY.  
 

 
   
MSO WATCHES/WARNINGS/ADVISORIES
 
 
MT...HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY  
NIGHT BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT  
REGION...FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT  
VALLEYS...POTOMAC/SEELEY LAKE REGION...WEST GLACIER REGION.  
 
ID...NONE.  

 
 

 
 
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