548  
FXUS65 KTFX 230253  
AFDTFX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREAT FALLS MT  
753 PM MST THU FEB 22 2018  
   
UPDATE
 
 
AFTER REVIEWING LATEST OBSERVATIONS AND MODEL DATA, DECIDED TO  
MAKE NO CHANGES TO TONIGHT'S FORECAST. IN ADDITION, THE BLIZZARD  
WARNING FOR THE UPCOMING GROUND BLIZZARD ALONG THE ROCKY MOUNTAIN  
FRONT AND EASTERN GLACIER COUNTY REMAINS VALID. PLEASE SEE THE  
PREVIOUS DISCUSSION FOR FURTHER DETAILS.  
JASZKA  
 

 
   
SYNOPSIS
 
 
SNOW SHOWERS WILL BE AROUND THROUGH THE WEEKEND, BUT WIDESPREAD  
AND SIGNIFICANT ACCUMULATING SNOW IS NOT EXPECTED AT LOWER  
ELEVATIONS. IT WILL BE WINDY AT TIMES THROUGH THE WEEKEND AS WELL  
WHICH WILL LEAD TO IMPACTS FROM BLOWING AND DRIFTING SNOW. ALONG  
THE ROCKY MOUNTAIN FRONT, GROUND BLIZZARD CONDITIONS ARE EXPECTED  
FRIDAY THROUGH EARLY SATURDAY MORNING AND POSSIBLY AGAIN ON  
SUNDAY.  
 

 
   
AVIATION
 
 
UPDATED 2313Z.  
 
MAINLY VFR EXPECTED NEXT 24-HOURS AS MULTIPLE DISTURBANCES SLIDE  
SOUTHEASTWARD OVER THE AREA. LIGHT SURFACE WINDS WILL IMPACT MUCH OF  
THE REGION. HOWEVER, GUSTY SOUTHWESTERLY TO WESTERLY SURFACE WINDS  
ARE EXPECTED TO DEVELOP ALONG THE ROCKY MOUNTAIN FRONT AROUND  
12Z/FRI AND THEN SPREAD EASTWARD TO NORTH-CENTRAL MT'S I-15 CORRIDOR  
AND VICINITY BY 18Z/FRI. WITHIN THIS AREA OF ENHANCED WINDS, GUSTS  
UP TO 35 KNOTS ARE EXPECTED ALONG THE PLAINS, WHILE GUSTS UP TO 50  
KNOTS WILL AFFECT THE IMMEDIATE ROCKY MOUNTAIN FRONT. THESE WINDS  
SHOULD RESULT IN BLOWING SNOW AND VSBY PRIMARILY RANGING FROM MVFR  
TO IFR, ESPECIALLY WEST OF I-15. HOWEVER, A GROUND BLIZZARD WITH  
VSBY DOWN TO LIFR IS EXPECTED TO DEVELOP ALONG THE ROCKY MOUNTAIN  
FRONT BETWEEN 12Z AND 18Z/FRI; THEN PERSIST THROUGH THE END OF THE  
TAF PERIOD. LASTLY, MOUNTAIN-OBSCURING SNOW SHOWERS REMAIN POSSIBLE,  
ESPECIALLY OVER SOUTHWEST MT.  
JASZKA  
 

 
   
PREV DISCUSSION
 
 
/ISSUED 413 PM MST THU FEB 22 2018/  
 
REST OF TODAY THROUGH SUNDAY NIGHT...THE MAIN CONCERNS THROUGH  
THIS WEEKEND WILL CONTINUE TO REVOLVE AROUND THE WIND AND  
ASSOCIATED IMPACTS FROM BLOWING/DRIFTING SNOW. THE BLIZZARD  
WARNING CONTINUES FOR ALL OF GLACIER COUNTY AND THE SOUTHERN ROCKY  
MTN FRONT FOR FRIDAY/FRIDAY NIGHT. WE HAVE ALSO ISSUED A WINTER  
STORM WATCH FOR THE POTENTIAL OF BLOWING/DRIFTING SNOW IMPACTS  
OVER THE PLAINS ON SUNDAY (MORE ON THAT BELOW).  
 
THE UPPER LEVEL TROUGH OVER THE WESTERN US WILL REMAIN IN PLACE  
THROUGH TONIGHT. AN UPPER LEVEL LOW WITHIN THIS TROUGH WILL KEEP A  
THREAT OF SNOW SHOWERS GOING ACROSS SW MT THROUGH THIS EVENING,  
ESPECIALLY THE MOUNTAINS, BUT WITH MINIMAL ACCUMULATIONS/IMPACTS.  
 
TWO DISTINCT SHORTWAVES WILL THEN TRAVERSE THE AREA, ONE FRIDAY  
AND ONE ON SUNDAY. BOTH WAVES WILL BRING BREEZY/WINDY CONDITIONS  
TO MUCH OF CENTRAL MONTANA. THE WIND ON FRIDAY/FRIDAY NIGHT WILL  
BE MORE PRESSURE GRADIENT-DRIVEN WITHIN THE DEVELOPING LEE-SIDE  
TROUGH, AND THE STRONGEST WINDS LOOK TO BE CONFINED MAINLY TO  
FAVORED FOOTHILLS AREAS FROM CUT BANK TO GREAT FALLS. A FRONT  
DROPPING SE ON SATURDAY MAY ALLOW A BRIEF DECREASE IN THE WINDS AS  
THE FLOW TURNS MORE NORTHWESTERLY. THE SHORTWAVE ON SUNDAY WILL  
LIKELY BE ACCOMPANIED BY A STRONGER LOW/MID LEVEL JET. COMBINED  
WITH A TIGHTENING PRESSURE GRADIENT, STEEPENING LAPSE RATES, AND A  
FRONTAL PASSAGE, THE STRONGER WINDS SHOULD SPREAD OUT OVER MUCH  
OF THE PLAINS. IN FACT, IT IS LIKELY THAT SEVERAL LOCATIONS WILL  
APPROACH OR EXCEED HIGH WIND CRITERIA FOR A SHORT TIME,  
ESPECIALLY AS THE FRONT PASSES THROUGH. WITH ALL THE SNOW ON THE  
GROUND, MUCH OF IT STILL LOOSE, WE EXPECT MORE WIDESPREAD IMPACTS  
FROM BLOWING/DRIFTING SNOW TO DEVELOP OVER THE PLAINS. WITH  
CONFIDENCE BEING HIGH ENOUGH, AND IN AN ATTEMPT TO GET THE MESSAGE  
OUT EARLY, WE DECIDED TO GO AHEAD AND ISSUE A WINTER STORM WATCH.  
PLEASE NOTE, THOUGH, THIS WATCH IS FOR BLOWING SNOW ONLY, NOT FOR  
FALLING/ACCUMULATING SNOW. THE GREATEST IMPACTS SUNDAY LOOK TO BE  
OPEN AREAS WHERE SIGNIFICANT DRIFTING OF SNOW COULD LEAD TO  
DIFFICULT TRAVEL. ONCE AGAIN, THOUGH, BLIZZARD OR NEAR-BLIZZARD  
CONDITIONS WILL BE POSSIBLE ALONG THE ROCKY MTN FRONT, INCLUDING  
BROWNING, HEART BUTTE, BABB, AND MARIAS PASS. EACH WAVE WILL BE  
ACCOMPANIED BY SCATTERED SNOW SHOWERS, BUT WIDESPREAD ACCUMULATING  
SNOW IS NOT EXPECTED AT THIS TIME. MARTIN  
 
MONDAY THROUGH WEDNESDAY...MAIN FORECAST CONCERNS ARE CONTINUED  
BELOW NORMAL TEMPERATURES, AND SHOTS FOR ADDITIONAL SNOWFALL AND  
GUSTY WINDS, ESPECIALLY ALONG THE CONTINENTAL DIVIDE.  
 
LARGE H500 TROUGH WILL BE IN PLACE ACROSS THE WESTERN CONUS TO BEGIN  
WITH AND GENERALLY PERSIST THROUGH THE PERIOD, WITH SUBTLE EMBEDDED  
WAVES ROTATING THROUGH THIS LARGE OVERALL PATTERN. LIGHT SNOW  
CHANCES ARE EXPECTED TO CONTINUE ALONG THE CONTINENTAL DIVIDE AND  
OVER THE MOUNTAINS OF SOUTHWEST MONTANA JUST ABOUT EVERY DAY,  
HOWEVER, ACCUMULATIONS OVER THIS TIMEFRAME APPEAR FAIRLY MINOR  
COMPARED TO THE PAST MONTH. TEMPERATURES WILL REMAIN WELL BELOW  
NORMAL (IE 15 TO 20 DEGREES) ACROSS BOTH NORTH CENTRAL AND  
SOUTHWEST MONTANA, WITH HIGH TEMPERATURES STRUGGLING INTO THE 20S  
AND OVERNIGHT LOWS FALLING INTO THE SINGLE DIGITS BELOW TO SINGLE  
DIGITS ABOVE. WINDS WILL BE GUSTY THROUGHOUT THE DAY ON MONDAY AND  
TUESDAY ACROSS NORTH CENTRAL MONTANA, BEFORE GRADUALLY DECREASING  
DURING THE OVERNIGHT HOURS TUESDAY NIGHT/WEDNESDAY MORNING. THESE  
GUSTY WINDS WILL LIKELY CONTINUE SOME BLOWING AND DRIFTING OF  
SNOWFALL, WHICH WILL ONLY HELP TO EXACERBATE ISSUES FROM OVER THE  
WEEKEND. - MOLDAN  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
GTF -6 22 10 30 / 10 0 0 30  
CTB -7 21 10 28 / 10 0 10 30  
HLN -5 22 10 29 / 20 0 10 40  
BZN -4 18 5 26 / 20 10 20 30  
WEY -11 19 0 19 / 20 10 40 70  
DLN -5 18 3 22 / 30 10 20 50  
HVR -17 14 3 20 / 10 0 0 20  
LWT -9 22 7 27 / 10 0 0 20  
 

 
   
TFX WATCHES/WARNINGS/ADVISORIES
 
 
WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING  
BLAINE...CASCADE...CHOUTEAU...EASTERN PONDERA...EASTERN TETON...  
FERGUS...HILL...JUDITH BASIN...LIBERTY...TOOLE.  
 
BLIZZARD WARNING FROM 6 AM FRIDAY TO 6 AM MST SATURDAY EASTERN  
GLACIER...NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY  
MOUNTAIN FRONT.  
 

 
 

 
 
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