418  
FXUS65 KGGW 220244  
AFDGGW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GLASGOW MT  
844 PM MDT SAT OCT 21 2017  
   
SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUN
 
 
900PM UPDATE:  
CHANGES FOR THE EVENING WERE MINIMAL. MAIN CONCERN WITH WINDS  
BECOMING LIGHT SO FAST... A FEW ISOLATED VALLEY AND DRAINAGE PRONE  
AREAS SUCH AS JORDAN AND COULEES AROUND DAWSON COUNTY HAVE ALREADY  
REACHED AND BROKEN MINIMUMS. FOR THIS REASON SHRINK-STRETCHED  
THESE LOCATIONS A LITTLE LOWER TO COMPENSATE FOR THE LOW  
DEWPOINTS ALREADY ESTABLISH FOR TONIGHT. GAH  
 
500PM UPDATE:  
TOOK A VERY HARD LOOK AT THE HIGH WIND WARNING FOR TOMORROW. UPON  
INVESTIGATION, FOUND MULTIPLE 12Z MODELS ARE PLACING A 700MB JET  
SPIKE OVER GARFIELD COUNTY. CMCREG, GFS, NMM, NAMNEST, DNG ETC...  
IN ADDITION EACH MODEL IS PLACING LAPSE RATES BETWEEN 7-9 C/KM  
ALONG THE FRONTAL PASSAGE AS IT MOVES UNDER THIS SPIKE. THESE  
MODELS ARE ALSO PLACING VERY LIGHT QPF IN PLACE NEXT TO THE  
BOUNDARY WITH THE PASSAGE. WE'VE SEEN THIS BEFORE TWICE ALREADY IN  
THE LAST WEEK, A RELATIVELY WARM AFTERNOON LEADS TO A LATE COLD  
FRONT WHICH GENERATES SHOWERS INTO A HIGH DEWPOINT DEPRESSION  
ENVIRONMENT. THE SHOWERS EVAPORATE, COOL, AND DRAG THE WIND SPIKE  
DOWN THE SURFACE WHICH EXCEEDS WELL BEYOND WHAT THE MODEL SURFACE  
WIND OUTPUT GIVES. BECAUSE OF THIS, EXPANDED THE HIGH WIND WARNING  
OVER PETROLEUM, GARFIELD, PRAIRIE, MCCONE, DAWSON, WIBAUX, AND  
RICHLAND COUNTY. 18Z RUN OF THE MODELS HAS MOVED THE SPIKE ONLY  
SLIGHTLY SOUTHEAST BY ABOUT 20 TO 30 MILES. SO, THE SPIKE ITSELF  
IS HIGH CONFIDENCE, BUT AREAL PLACEMENT IS ONLY MODERATE  
CONFIDENCE. GAH  
 
PREVIOUS SHORT TERM DISCUSSION:  
BY 00Z THIS EVENING, THE BASE OF THE TROUGH WILL BE FULLY INTO  
NORTH DAKOTA TO BE FOLLOWED BY A WEAK RIDGE OVER THE MONTANA  
PRAIRIE TONIGHT. WINDS WILL BE DIMINISHING AS CLEARING SKIES ALLOW  
FOR AIRMASS TO DECOUPLE AND THE RIDGING WEAKENS THE WINDS ALOFT.  
EXPECT MOST LOWS TO FALL INTO THE 30S DUE TO THE MUCH COOLER AIR  
IN PLACE.  
 
VERY STRONG PACIFIC JET PUNCHES ACROSS THE ROCKIES ON SUNDAY,  
FORMING AN ALBERTA CLIPPER IN THE MORNING. STACKED WESTERLY FLOW  
WILL BRING THE WINDS DOWN ACROSS THE PRAIRIE FAIRLY QUICKLY IN THE  
MORNING. WITH 50 TO 60 KTS AT 850 AND 700MB WILL UPGRADE HIGH  
WIND WATCH TO A WARNING FOR SOUTHWEST PHILLIPS COUNTY. NEAR TERM  
MODELS INDICATE THAT RIDGE TOPS ACROSS THE REMAINDER OF PHILLIPS  
COUNTY WILL LIKELY SEE GUSTS TO 55 OR 60 MPH, SO WILL EXPAND  
WARNING INTO ALL OF PHILLIPS COUNTY. WITH THE WINDS INCREASING  
EARLY IN THE DAY, THE LAKE WIND ADVISORY WAS EXTENDED FROM TODAY,  
ALTHOUGH WINDS WILL BE TEMPORARILY DIMINISHING TONIGHT. WITH  
WESTERLY WIND, HIGHS WILL WARM UP 5-10F HIGHER THAN SATURDAY.  
 
TEMPLER  
 
   
LONG TERM...SUN NIGHT THROUGH SAT
 
 
AFTERNOON UPDATE:  
THE CLIPPER SYSTEM EXPANDS INTO A DEEP TROUGH AS IT HEADS TOWARDS  
THE GREAT LAKES. THIS WILL MAINTAIN STRONG NORTHWEST WINDS LOCALLY  
THROUGH MONDAY. THIS NEW INFUSION OF CAA WILL KNOCK HIGHS DOWN  
TO NORMAL AGAIN. THE NEXT MAJOR CHANGE WILL COME FROM A TROUGH IN  
WESTERN CANADA DIGGING THROUGH THE NORTHERN HIGH PLAINS ON  
WEDNESDAY. THIS WILL BRING MUCH COOLER TEMPERATURES, A QUICK SHOT  
OF PRECIPITATION, SOME MIXED, WEDNESDAY NIGHT AND THURSDAY, ALONG  
WITH STRONG WINDS AGAIN. USED FB THROUGH THURSDAY TO UPDATE WITH  
THE LATEST GUIDANCE.  
 
TEMPLER  
 
PREVIOUS LONG TERM DISCUSSION:  
CLIPPER SYSTEM DIVES TOWARD THE GREAT LAKES EARLY IN THE WEEK,  
WITH UPPER TROF DIGGING OVER THE NORTHERN PLAINS. COLD AIR  
ADVECTION AND PRESSURE RISES BEHIND THE CLIPPER WILL KEEP STRONG  
WINDS OVER THE REGION SUNDAY NIGHT INTO MONDAY, WITH LAKE WIND  
ADVISORY EXTENDED THROUGH MONDAY AFTERNOON.  
TUESDAY INTO WEDNESDAY, A WARMING AND DRYING TREND RETURNS TO THE  
AREA THANKS TO HIGH PRESSURE BUILDING OVER THE NORTHERN ROCKIES.  
 
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT, A STRONG COLD FRONT PUSHES  
THROUGH THE REGION. MODELS DIFFERING ON HOW QUICKLY THIS SYSTEM  
MOVES AND DEVELOPS, BUT SOME PRECIPITATION WEDNESDAY NIGHT AND  
COLDER TEMPERATURES ON THURSDAY. EBERT  
 

 
   
AVIATION
 
 
LLWS: WITH AN INVERSION AND WINDS ALOFT BEING STRONG LOW LEVEL  
WIND SHEAR WILL BE A CONCERN FROM 12-17Z.  
 
CROSSWIND: EXPECT STRONG CROSSWINDS FOR N-S RUNWAYS FROM 17-02Z.  
 
FLIGHT CAT: VFR.  
 
SYNOPSIS: THE UPPER LEVEL TROUGH EXITS EAST TO BE REPLACED  
BY A WEAK RIDGE WITH DIMINISHING WINDS OVERNIGHT. THEN SUNDAY AN  
ALBERTA CLIPPER RACES THROUGH THE AREA TO BRING VERY STRONG WEST  
WINDS OF 30-40G50KT THAT WILL MIX DOWN TO THE GROUND DURING THE  
AFTERNOON. MODELS INDICATE SCATTERED LIGHT AFTERNOON SHOWERS  
WHICH COULD BRING EVEN STRONGER WINDS TO THE GROUND IN ISOLATED  
POCKETS.  
 
WIND: WEST TO SOUTHWEST AT LESS THAN 10 KTS OVERNIGHT, VEERING TO  
THE WEST AND INCREASING AFTER SUNUP TO 30-40G50KTS BY THE LATE  
AFTERNOON, DECREASING AFTER DARK TO LESS THAN 20 KTS.  
 
TEMPLER/GAH  
 

 
   
GLASGOW WATCHES/WARNINGS/ADVISORIES
 
 
HIGH WIND WARNING FROM 10 AM TO 8 PM MDT SUNDAY FOR CENTRAL AND  
SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...DAWSON...  
GARFIELD...MCCONE...NORTHERN PHILLIPS...PETROLEUM...PRAIRIE...  
RICHLAND...SOUTHWEST PHILLIPS...WIBAUX.  
 
LAKE WIND ADVISORY UNTIL 10 AM MDT SUNDAY FOR FORT PECK LAKE FOR  
CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...  
GARFIELD...MCCONE...PETROLEUM.  
 
LAKE WIND ADVISORY FROM 8 PM SUNDAY TO 6 PM MDT MONDAY FOR FORT  
PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND  
SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.  
 

 
 

 
 
WEATHER.GOV/GLASGOW  
 
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