304  
FXUS65 KGGW 052339  
AFDGGW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GLASGOW MT  
439 PM MST SAT DEC 5 2020  
   
DISCUSSION
 
 
AFTERNOON UPDATE:  
QUICK UPDATE TO THE FORECAST FOR LATE THIS EVENING INTO SUNDAY  
MORNING. WITH DEWPOINTS FAR EXCEEDING OVERNIGHT LOWS EITHER ONE  
OF TWO THINGS WILL HAPPEN. EITHER A. WE WILL REACH SATURATION AND  
FOG WILL BEGIN TO FORM IN LOW LYING DRAINAGE VALLEYS. OR B. EXCESS  
MOISTURE WILL GATHER ON SURFACES PRODUCING EXCESSIVE FROST SUNDAY  
MORNING. TYPICALLY B OCCURS WITH A FULL COVERAGE SNOW PACK TO  
SUCK UP THE MOISTURE AT THIS TIME OF YEAR, BUT WITH OVER HALF THE  
GROUND EXPOSED, THE COLD TRAP MAY NOT BE EFFICIENT ENOUGH TO RID  
THE RID THE EXCESSIVE SURFACE MOISTURE. I'M A LITTLE OVER 50/50 IN  
CONFIDENCE AND ERRING MORE TOWARD THE FOG SIDE FOR TONIGHT. GAH  
 
AFTERNOON DISCUSSION:  
QUIET WEATHER WILL CONTINUE INTO NEXT WEEK AS A RIDGE DOMINATES  
THE WEATHER PATTERN. HIGH TEMPERATURES HAVE BEEN OVERPERFORMING A  
BIT AND THAT WILL CONTINUE TO BE THE CASE THROUGH AT LEAST  
TUESDAY. HAVE GONE AHEAD AND BUMPED UP HIGH TEMPERATURES EACH DAY,  
PARTICULARLY IN LOCATIONS WHERE MODELS ARE OVERESTIMATING SNOW  
COVER.  
 
THIS MEANS MUCH OF NORTHEAST MONTANA WILL SEE TEMPERATURES RISING  
INTO THE 50S BY TUESDAY WITH SOME 60S EXPECTED ACROSS PETROLEUM  
COUNTY.  
 
A SHORT-WAVE TROUGH WILL MOVE THROUGH THE AREA WEDNESDAY NIGHT  
INTO THURSDAY. THERE WILL BE A SLIGHT CHANCE OF SOME RAIN/SNOW  
SHOWERS WITH THIS SYSTEM, BUT NO SIGNIFICANT IMPACTS ARE EXPECTED.  
THIS WILL, HOWEVER, LEAD A CHANGE IN THE WEATHER PATTERN WITH  
TEMPERATURES RETURNING BACK TO NEAR NORMAL BY THE END OF THE WEEK  
WITH HIGHS IN THE UPPER 20S TO UPPER 30S.  
 
-MOTTICE  
 

 
   
AVIATION
 
 
FLIGHT CAT: VFR - LIFR  
 
DISCUSSION: MAINLY DRY WEATHER CONTINUES THROUGH THE PERIOD. FOG  
WILL BE POSSIBILITY FOR THE MILK AND MISSOURI RIVER VALLEYS  
TONIGHT INCLUDING AT KGGW AND KOLF. MAIN ISSUE IS THAT DEWPOINT  
IS CURRENTLY FAR ABOVE THE OVERNIGHT LOWS. HOWEVER, WITH LIMITED  
SNOWPACK THE USUAL MOISTURE TRAP WILL HAVE A MORE DIFFICULT TIME  
PERFORMING ITS WORK, WHICH MAY JUST BE ENOUGH TO REACH SATURATION  
IN DRAINAGE ZONES FOR FOG. CONFIDENCE IS ONLY MODERATE BUT IT WAS  
HIGH ENOUGH TO PLACE IN THE TAFS TONIGHT OR SLIGHTLY ABOVE A 50/50  
CHANCE. IF FOG DOESN'T HAPPEN THERE WILL BE EXCESSIVE FROST.  
 
WIND: WINDS WILL BE LIGHT AND VARIABLE THROUGH SUNDAY MORNING.  
BECOMING WEST SUNDAY AFTERNOON.  
 
GAH  
 

 
   
GLASGOW WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
WEATHER.GOV/GLASGOW  
 
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