190  
FXUS65 KTFX 181700  
AFDTFX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREAT FALLS MT  
1100 AM MDT THU JUL 18 2024  
 
AVIATION SECTION UPDATED  
   
SYNOPSIS
 
 
A PASSING WEATHER SYSTEM WILL BRING AN INCREASED CHANCE FOR  
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS TODAY. A FEW STORMS MAY  
BE ON THE STRONGER SIDE WITH BRIEF STRONG, GUSTY WINDS,  
LIGHTNING, AND DOWNPOURS, ESPECIALLY IN CENTRAL AND NORTH-CENTRAL  
MONTANA. OTHERWISE, THE HOT AND MOSTLY DRY WEATHER PATTERN LOOKS  
TO CONTINUE THROUGH THE WEEKEND AND BEYOND.  
 

 
   
UPDATE
 
 
NO UPDATE PLANNED FOR THE MORNING FORECAST, AS CURRENT FORECAST IS  
ON TRACK. ISOLATED THUNDERSTORMS EAST OF SHELBY AND EAST OF ULM  
THIS MORNING ARE SLOWLY DIMINISHING. DO EXPECT MORE WIDESPREAD  
THUNDERSTORM ACTIVITY THIS AFTERNOON OVER NORTH CENTRAL MT. AN  
ISOLATED SEVERE STORM IS POSSIBLE, WITH THE MAIN THREAT BEING  
STRONG WIND GUSTS. AFTERNOON TEMPERATURES WILL RISE INTO THE 90S  
FOR MOST LOWER ELEVATION LOCATIONS, WITH AREAS OF SMOKE/HAZE  
THROUGHOUT THE DAY. BRUSDA  
 

 
   
AVIATION
 
 
18/18Z TAF PERIOD  
 
A LINE OF SHOWERS CURRENTLY EAST OF A LINE FROM HAVRE TO LEWISTOWN  
WILL CONTINUE TO MOVE EAST EARLY THIS AFTERNOON AND TRANSITION INTO  
THUNDERSTORMS. EXPECT A REDEVELOPMENT OF THUNDERSTORMS FURTHER WEST  
OVER THE CWA BY MID AFTERNOON. SOME STORMS LATER THIS AFTERNOON  
COULD PRODUCE STRONG WIND GUSTS. MOST STORMS WILL EXIT THE EASTERN  
PORTIONS OF THE CWA BY 03Z FRI. SMOKE IS MOVING THROUGH THE CWA AS  
WELL, REDUCING DISTANT VISIBILITY AND OBSCURING MOUNTAINS. THAT WILL  
CONTINUE THROUGH THE PERIOD. BRUSDA  
 
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION WEATHER  
AND HAZARD INFORMATION.  
 

 
   
PREV DISCUSSION
 
 
/ISSUED 530 AM MDT THU JUL 18 2024/  
 
SHOWERS AND EMBEDDED THUNDERSTORMS ARE APPROACHING THE  
CONTINENTAL DIVIDE THIS MORNING WHILE THE RESPONSIBLE SHORTWAVE  
CENTERED OVER E WA CONTINUES TO TREK EASTWARD TOWARD THE NORTHERN  
ROCKIES. THIS INITIAL AREA OF CONVECTION LOOKS TO REACH THE ROCKY  
MOUNTAIN FRONT AN HOUR OR TWO EARLY, BUT WILL STILL FOLLOW THE  
OVERALL EXPECTED PATH THROUGH THE NORTH-CENTRAL PLAINS THROUGH THE  
MORNING HOURS. THIS SHOULDN'T BE TOO IMPACTFUL, BUT THERE WILL BE  
AN ADDITIONAL ROUND OF WIDELY SCATTERED SHOWERS AND STORMS FOR  
THIS AFTERNOON AND EVENING.  
 
THE BOUNDARY LAYER IS STILL RELATIVELY DRY, SO THERE'S AN  
EXPECTATION FOR A MIX OF WET AND DRY STORMS WITH THE BEST CHANCE  
FOR DRIER STORMS SOUTH OF A HELENA TO LEWISTOWN LINE. THE  
COMBINATION OF HIGHER PWATS APPROACHING THE 0.75 TO 1 INCH MARK,  
WITH ML CAPE VALUES AROUND 500 TO 1,000 J/KG AND INVERTED V  
PROFILES MAY RESULT IN AT LEAST A FEW STORMS BECOMING STRONG TO  
SEVERE WITH STRONG, GUSTY WINDS, BRIEF DOWNPOURS, AND EVEN SOME  
HAIL. OF COURSE THE OCCURRENCES OF RAIN AND HAIL, IF ANY, LOOK TO  
BE RESERVED TO THE CENTRAL/NORTH-CENTRAL AREAS, PARTICULARLY AREAS  
EAST OF I15. SINCE SOUTHWESTERN AREAS WILL HAVE LESS AVAILABLE  
MOISTURE, GUSTY WINDS AND LIGHTNING IN THE PRESENCE OF LITTLE  
RAINFALL WILL BE MORE OF A CONCERN.  
 
MOST SHOWER AND STORM ACTIVITY WILL BEGIN TO DIMINISH DURING THE  
EVENING HOURS, THOUGH AT LEAST SOME SHOWERS AND STORMS LINGERING  
INTO THE OVERNIGHT HOURS CAN BE EXPECTED, MOSTLY FOR HILL, BLAINE,  
FERGUS, AND EASTERN CHOUTEAU COUNTIES. THESE SAME LOCATIONS MAY  
BE BECOME SUSCEPTIBLE TO PATCHY FOG DEVELOPMENT ONCE THINGS DO  
PARTIALLY CLEAR OUT LATE TONIGHT INTO FRIDAY MORNING.  
 
DESPITE ALL THE TALK OF TODAY'S MOISTURE, RIDGING WILL STILL BE  
STRONG ENOUGH TO WARM MOST LOWER ELEVATIONS IN THE 90S THIS  
AFTERNOON AND THE OVERALL HOT AND DRY PATTERN WILL PERSIST THROUGH  
THE WEEKEND INTO NEXT WEEK. ONCE TODAY'S SHORTWAVE EXITS THE  
REGION LATER TONIGHT, INSTANCES OF SHOWERS AND THUNDERSTORMS LOOK  
TO BECOME MUCH MORE ISOLATED AGAIN, BUT WON'T COMPLETELY GO AWAY.  
THE LATEST 3 TO 7 DAY CLUSTER ANALYSIS SHOWS SOME RIDGE  
AMPLIFICATION EARLY NEXT WEEK BEFORE BECOMING DAMPENED SOME BY  
TROUGHING LATE IN THE WEEK. TEMPERATURES WILL ROUGHLY FOLLOW THIS  
PATTERN BY RISING A FEW DEGREES TUESDAY AND WEDNESDAY AND THEN  
DROPPING OFF A LITTLE AGAIN ON THURSDAY. - RCG  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
GTF 92 59 93 61 / 30 20 0 0  
CTB 89 54 92 58 / 30 20 0 10  
HLN 97 61 97 63 / 20 10 0 0  
BZN 94 56 93 56 / 30 30 0 0  
WYS 85 44 84 43 / 50 40 20 10  
DLN 90 54 89 54 / 30 10 10 0  
HVR 93 59 94 62 / 50 50 0 10  
LWT 90 55 87 58 / 40 50 10 0  
 

 
   
TFX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
HTTP://WWW.WEATHER.GOV/GREATFALLS  
 
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