220  
FXUS65 KMSO 181854  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
1254 PM MDT THU JUL 18 2024  
   
..EXCESSIVE HEAT CONTINUES FRIDAY THROUGH EARLY NEXT WEEK
 
 
   
DISCUSSION
 
A WEAK CIRCULATION MOVING THROUGH THE HIGH PRESSURE  
RIDGE CURRENTLY OVER THE NORTHERN ROCKIES BROUGHT ABOUT LIGHTNING  
OVERNIGHT THROUGH THIS MORNING, BUT IS NOW SHIFTING TO THE NORTH  
AND EAST. IN ITS WAKE, WE EXPECT A FEW ISOLATED THUNDERSTORMS TO  
DEVELOP ACROSS SOUTHWEST MONTANA (ALONG AND SOUTH OF GRANITE AND  
SILVER BOW COUNTY), WITH A FEW RIDGETOP STORMS DEVELOPING ALONG  
THE MONTANA AND CANADA BORDER AS WELL. OVERALL, THE THUNDERSTORM  
THREAT WILL LESSEN GREATLY AS WE HEAD INTO FRIDAY AND HIGH  
PRESSURE RE-AMPLIFIES.  
 
MODEL CONSENSUS REMAINS STRONG IN SEVERAL DAYS OF EXCESSIVE HEAT  
OCCURRING FRIDAY AND CONTINUING INTO NEXT WEEK. TEMPERATURES WILL  
SOAR INTO THE 100-115 DEGREE RANGE FOR MUCH OF CENTRAL IDAHO AND  
WESTERN MONTANA VALLEYS. MIDSLOPES AND RIDGETOPS WILL ALSO FEEL  
THE HEAT, WITH HIGH ELEVATION TEMPERATURES RANGING IN THE 70S TO  
80S DURING THE DAY. AS WE HAVE MENTIONED PREVIOUSLY, WILDFIRE  
SMOKE MAY INHIBIT FULL DAYTIME HEATING, WHICH WOULD KEEP THE MOST  
EXTREME TEMPERATURE VALUES FROM OCCURRING. WHILE THAT POTENTIAL  
STILL VERY MUCH EXISTS, WITH SUCH PROLONGED EXCESSIVE HEAT  
EXPECTED, AND OVERNIGHT LOW TEMPERATURES REMAINING IN THE 60S TO  
70S, WE ELECTED TO ISSUE BOTH HEAT WARNINGS AND HEAT ADVISORIES TO  
COVER A LARGE PORTION OF WESTERN MONTANA AND CENTRAL IDAHO. FOR  
MORE INFORMATION ON YOUR EXACT AREA AND ANY HEAT IMPACTS EXPECTED,  
PLEASE VISIT WWW.WEATHER.GOV/MISSOULA.  
 
HEAT SAFETY FOR BOTH HUMANS AND ANIMALS ALIKE WILL BE OF UTMOST  
IMPORTANCE DURING THIS TIME AND SHOULD NOT BE TAKEN LIGHTLY. WITH  
THE INFLUENCE OF SMOKE IN THE AIR AROUND THE REGION, DEGRADED AIR  
QUALITY WILL ONLY ADD TO THE STRESS ON THE BODY DURING THIS TIME,  
AND THOSE WITH SENSITIVITIES TO BOTH HEAT AND POOR AIR QUALITY  
SHOULD EXERCISE SPECIAL CARE TO ENSURE THEY REMAIN WELL.  
 
WHEN WILL RELIEF COME? WE'RE STILL LOOKING AT THE HIGH PRESSURE  
RIDGE FINALLY SHIFTING EAST BY THE MIDDLE OF NEXT WEEK, WITH A  
LOW PRESSURE CENTER MOVING INLAND FROM THE WASHINGTON COAST BY  
FRIDAY. TEMPERATURES WILL COOL A FEW DEGREES EACH DAY BEGINNING AS  
EARLY AS TUESDAY (JULY 23), BUT ANY MAJOR IMPROVEMENT WILL DEPEND  
SOLELY ON THE TIMING AND TRACK OF THE LOW PRESSURE.  
 

 
   
AVIATION
 
ISOLATED THUNDERSTORMS ACCOMPANIED BY 15-25 KT GUSTS ARE  
EXPECTED ALONG THE DIVIDE THIS AFTERNOON DIMINISHING THIS  
EVENING. OTHERWISE, HOT AND DRY CONDITIONS WILL CONTINUE INTO THE  
WEEKEND, WINDS WILL BE LIGHT ASIDE FROM THE TYPICAL AFTERNOON  
GUSTS OF 15-20 KTS. HIGH DENSITY ALTITUDE WILL CONTINUE TO BE A  
CONCERN GIVEN THE ABNORMALLY HOT TEMPERATURES. SMOKE FROM REGIONAL  
AND LOCAL WILDFIRES WILL CREATE HAZY SKIES AND LOCALIZED  
VISIBILITY REDUCTIONS.  
 

 
   
MSO WATCHES/WARNINGS/ADVISORIES
 
 
MT...EXCESSIVE HEAT WARNING FROM 1 PM FRIDAY TO MIDNIGHT MDT TUESDAY  
NIGHT FOR KOOTENAI/CABINET REGION...LOWER CLARK FORK REGION.  
 
HEAT ADVISORY FROM 1 PM FRIDAY TO MIDNIGHT MDT TUESDAY NIGHT FOR  
FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT VALLEYS...  
POTOMAC/SEELEY LAKE REGION...WEST GLACIER REGION.  
 
ID...EXCESSIVE HEAT WARNING FROM NOON FRIDAY TO 11 PM PDT TUESDAY FOR  
LOWER HELLS CANYON/SALMON RIVER REGION...NORTHERN  
CLEARWATER MOUNTAINS...OROFINO/GRANGEVILLE REGION...  
SOUTHERN CLEARWATER MOUNTAINS.  
 

 
 

 
 
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