807  
FXUS65 KGGW 240140  
AFDGGW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GLASGOW MT  
740 PM MDT WED MAY 23 2018  
   
DISCUSSION
 
 
730PM UPDATE:  
CHANGES TO THE FORECAST REVOLVED AROUND GETTING POPS IN PLACE  
WHERE THUNDERSTORMS HAVE DEVELOPED AND BEGUN MOVING INTO.  
CURRENTLY DEWPOINTS HAVE RISEN INTO THE 60S FOR THE AFTERNOON AND  
EVENING HOURS ACROSS THE YELLOWSTONE VALLEY AND ARE PROVIDING  
PLENTY OF MOISTURE ALONG WITH LIFT FROM A PASSING DISTURBANCE.  
THIS IS LEADING TO STORMS WHICH HAVE BEGUN GENERATING QUARTER AND  
GOLF BALL SIZED HAIL. THIS TREND IS EXPECTED TO CONTINUE THROUGH  
ROUGHLY 9PM AND THEN SLOWLY TAPERING DOWN THROUGH MIDNIGHT.  
MEANWHILE, SHOWERS SHOULD TRANSITION TO THE NORTHEAST INTO THE  
DAKOTAS. GAH  
 
PREVIOUS AFTERNOON DISCUSSION:  
UPPER LOW MOVING NORTHEAST INTO CENTRAL MONTANA LATE TODAY  
ALLOWING FOR UPPER DIFFLUENT FLOW ABOVE THE MID-LEVEL DRY SLOT.  
SOME SHOWERS AND THUNDERSTORMS HAVE FIRED UP OVER SOUTHEAST AND  
SOUTH-CENTRAL MONTANA AND NORTHERN WYOMING THIS AFTERNOON. THESE  
SHOULD THREATEN THE SE ZONES THIS EVENING WHERE THE BEST SHEAR  
ARE. HAVE ADDED SEVERE WORDING IN TO THIS AREA ACCORDINGLY.  
 
LOW PRESSURE THEN LIFTS NORTHEAST OF THE AREA THURSDAY WITH  
PARENT UPPER LOW OVER THE PRAIRIE PROVINCES. UPPER PIECES OF  
ENERGY WITH DIURNAL HEATING WILL ALLOW FOR A FEW LEFTOVER  
SHOWERS/TSTORMS MAINLY IN THE NORTHERN ZONES THROUGHOUT THE DAY.  
 
UPPER RIDGE THEN BUILDS IN FOR FRIDAY ALLOWING FOR TEMPERATURES TO  
RISE INTO THE 80S THAT CONTINUES INTO SATURDAY. THEN AN UPPER LOW  
FROM THE SW MOVES IN, BRINGING INCREASE CHANCES FOR SHOWERS AND  
THUNDERSTORMS SATURDAY NIGHT THROUGH MONDAY. THIS IS WETTER  
SOLUTION THAN WHAT WAS EXPECTED A FEW DAYS AGO.  
 
THE MAIN THING TO STRESS - LATE SATURDAY WILL SEE THE INCREASE  
CHANCE OF SEVERE THUNDERSTORMS.  
 
THIS SYSTEM MOVES OUT MID WEEK, BUT A LONGWAVE TROUGH SETS UP  
OVER THE WESTERN STATES AND THUS UNSETTLED CONDITIONS CAN BE  
EXPECTED THROUGH THE END OF THE WEEK. TFJ  
 

 
   
AVIATION
 
 
FLIGHT CAT: VFR TO MVFR  
 
SYNOPSIS: A DISTURBANCE MOVING OUT OF THE GREAT BASIN AND INTO  
NORTHEAST MONTANA HAS PROVIDED LIFT FOR THUNDERSTORMS THIS  
EVENING WHICH COULD BECOME SEVERE AS THEY MOVE OVER THE TERMINALS.  
THE MAIN THREAT WILL BE HAIL. TIMING FOR SEVERE CHANCES SHOULD  
LAST THROUGH ROUGHLY 03Z AND THEN SUBSIDE INTO 06Z. LIGHT FOG WILL  
BE POSSIBLE IN THE MORNING HOURS ALONG THE YELLOWSTONE VALLEY BUT  
WILL LIKELY BE VERY SPOTTY WITH FEW IMPACTS EXPECTED NEAR THE  
TERMINALS.  
 
WIND: LIGHT AND VARIABLE THROUGH TONIGHT EXCEPT NEAR THUNDERSTORMS  
WHICH COULD GUST AS HIGH AS 25 KTS. BECOMING WEST THURSDAY AT 10  
TO 15 KTS.  
 
GAH  
 

 
   
GLASGOW WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
WEATHER.GOV/GLASGOW  
 
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