006  
FXUS65 KMSO 020847  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
247 AM MDT FRI JUN 2 2023  
   
DISCUSSION  
 
GOES WATER VAPOR IMAGERY THIS MORNING REVEALS A LOW PRESSURE  
SYSTEM ACROSS NORTH-CENTRAL WYOMING. REGIONAL RADAR OBSERVATIONS  
SHOW WIDESPREAD PRECIPITATION NORTH AND WEST OF THE LOW ACROSS  
CENTRAL MONTANA. THE LOW PRESSURE SYSTEM WILL TRACK OVER  
YELLOWSTONE NATIONAL PARK LATE THIS MORNING INTO THE AFTERNOON,  
BRINGING AN INCREASE IN SHOWER ACTIVITY ALONG THE DIVIDE AND IN  
SOUTHWEST MONTANA. THUNDERSTORMS WILL DEVELOP AFTER 100PM MDT,  
WITH THE BEST FOCUS ACROSS IDAHO COUNTY AND LEMHI COUNTY, WHERE  
THERE IS A 30-40% PROBABILITY FOR LIGHTNING. PRECIPITATION WILL  
FOCUS EAST OF HIGHWAY 93 AND ALONG THE I-90 CORRIDOR EAST OF  
MISSOULA, WHERE NBM PROJECTS A 40-50% CHANCE FOR 0.25” ACROSS  
VALLEY AREAS. PROBABILITIES FOR 0.25” INCREASE TO 70% ACROSS  
MOUNTAIN AREAS. DRIER AIR WILL LIMIT THE POTENTIAL FOR SHOWER  
ACTIVITY ACROSS NORTHWEST MONTANA, ESPECIALLY ALONG THE ID/MT  
BORDER.  
 
ENSEMBLE MODEL GUIDANCE REMAINS LOCKED INTO A BLOCKING RIDGE OF  
HIGH PRESSURE EXTENDING FROM THE CENTRAL US NORTHWARD INTO  
SASKATCHEWAN AND MANITOBA CANADA THIS WEEKEND INTO MID NEXT WEEK.  
A PERSISTENT SOUTHERLY FLOW PATTERN WILL MAINTAIN ABOVE NORMAL  
ATMOSPHERIC MOISTURE ACROSS THE NORTHERN ROCKIES. PUSHES OF  
MOISTURE WILL BE TRANSPORTED BY UPPER LEVEL WAVES TRACKING FROM  
THE CENTRAL PLAINS OVER THE ROCKIES. DAILY SHOWERS AND  
THUNDERSTORMS REMAIN IN THE FORECAST, WITH ACTIVITY FOCUSING  
ACROSS LEMHI COUNTY, SOUTHWEST MONTANA, AND AREAS ALONG THE  
CONTINENTAL DIVIDE.  
 
BY WEDNESDAY AND THURSDAY NEXT WEEK, CONFIDENCE IS HIGHER THAN  
NORMAL FOR A HIGHER ATMOSPHERIC MOISTURE, AS PRECIPITABLE WATER  
VALUES REACH 200% OF NORMAL (AS SEEN IN EPS/GEFS/GEPS). MOISTURE  
TRANSPORT WILL EXTEND INTO NORTHWEST MONTANA, WHERE NBM HAS A  
20-30% PROBABILITY FOR 0.50” OR MORE PRECIPITATION DURING A  
48-HOUR PERIOD ENDING THURSDAY EVENING. /LUKINBEAL  
 
 
   
AVIATION  
 
A LOW PRESSURE SYSTEM WILL TRACK OVER YELLOWSTONE NATIONAL PARK  
LATE THIS MORNING INTO THE AFTERNOON, BRINGING AN INCREASE IN  
SHOWER ACTIVITY ALONG THE DIVIDE AND IN SOUTHWEST MONTANA. THE  
ATMOSPHERE WILL DESTABILIZE ACROSS IDAHO COUNTY AND LEMHI COUNTY,  
WHERE THERE IS A 30-40% PROBABILITY FOR THUNDERSTORMS AFTER  
02/1900Z, OR 1PM MDT. AREAS OF LOW CEILINGS AND PRECIPITATION  
WILL FOCUS EAST OF US-93 AND ALONG THE I-90 CORRIDOR EAST OF  
MISSOULA, WHERE NBM PROJECTS A 40-50% CHANCE FOR 0.25” ACROSS  
VALLEY AREAS. DRIER AIR WILL LIMIT THE POTENTIAL FOR SHOWER  
ACTIVITY ACROSS NORTHWEST MONTANA, ESPECIALLY ALONG THE ID/MT  
BORDER. /LUKINBEAL  
 
 
   
CLIMATE  
 
THE THEME OF WARM OVERNIGHT TEMPERATURES OBSERVED DURING MAY,  
WILL CONTINUE THROUGH THE FIRST WEEK OF JUNE. MISSOULA SET THE  
WARMEST MAY LOW TEMPERATURE AVERAGE IN MAY, WITH KALISPELL AND  
BUTTE RECORDING THE 3RD AND 6TH WARMEST RESPECTIVELY. CONFIDENCE  
IS HIGH FOR A BROAD RIDGE OF HIGH PRESSURE TO MAINTAIN ABOVE  
NORMAL TEMPERATURES AND ATMOSPHERIC MOISTURE DURING THE NEXT 7  
DAYS. LOWS WILL RUN ABOUT 10 DEGREES ABOVE NORMAL, AS OVERNIGHT  
TEMPERATURES DROP INTO THE 50S ACROSS VALLEY AREAS THROUGH JUNE  
8TH.  
 
THE NWS MISSOULA HAS RELEASED THE 2023 SUMMER OUTLOOK FOR THE  
NORTHERN ROCKIES, WHICH CAN BE FOUND ON OUR YOUTUBE CHANNEL AT  
HTTPS://WWW.YOUTUBE.COM/WATCH?V=SC2FCEZJYO0  
 
 
   
MSO WATCHES/WARNINGS/ADVISORIES  
 
MT...NONE.  
ID...NONE.  
 
 
 
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