327
FXUS65 KMSO 190705
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
105 AM MDT TUE MAY 19 2026
DISCUSSION
KEY MESSAGES:
- SHOWERS AND ISOLATED THUNDERSTORMS THROUGH WEDNESDAY, MAINLY
ACROSS NORTHWEST MONTANA AND OVER THE CONTINENTAL DIVIDE.
- RETURN TO SUMMER-LIKE CONDITIONS AS MODERATING TEMPERATURES
ARE EXPECTED LATE WEEK INTO NEXT WEEKEND.
AFTER A COLD START THIS MORNING, TEMPERATURES MODERATE THROUGH
SATURDAY. A FEW SHOWERS OR ISOLATED THUNDERSTORMS WILL BE POSSIBLE
THIS AFTERNOON IN NORTHWEST MT AND ALONG THE CONTINENTAL DIVIDE. A
FEW SHOWERS ON MONDAY WERE ABLE TO PRODUCE 0.10 TO 0.15 INCHES AND
WITH SIMILAR PRECIPITABLE WATERS TODAY, SIMILAR RESULTS ARE
EXPECTED. MOST SHOWERS HOWEVER WILL BE CHARACTERIZED AS VERY
LIGHT.
WEDNESDAY THE MODELS ARE ATTEMPTING TO CLOSE OFF A LOW PRESSURE
SYSTEM OVER EASTERN ALBERTA AND WESTERN SASKATCHEWAN. THE RESULTS
FOR US STILL SEEM UP IN THE AIR, HOWEVER THERE ARE HINTS OF AN
UPPER LEVEL COLD FRONT PUSHING SOUTHWEST ACROSS WESTERN MT. IF
THIS WAS TO HAPPEN, DISORGANIZED SHOWER ACTIVITY MAY BECOME
ORGANIZED ALONG THAT BOUNDARY AS IT MOVES SOUTHWEST. OUR CURRENT
FORECAST KEEPS THE FAVORED AREA FOR PRECIPITATION FROM THE
FLATHEAD AND MISSION VALLEYS AND EASTWARD ALONG THE CONTINENTAL
DIVIDE. MISSOULA SOUTH THROUGH THE BITTERROOT AND I-90 WEST OF
MISSOULA WILL SEE LIGHTER PRECIPITATION BUT POTENTIALLY AN
ISOLATED THUNDERSTORM. THUNDERSTORM ACTIVITY WILL BE SCATTERED
THROUGH NORTHWEST MT AND ALONG THE CONTINENTAL DIVIDE. GRAUPEL,
SMALL HAIL, AND GUSTY OUTFLOWS 25-35 MPH WILL BE POSSIBLE. OF
NOTE, THE CORE OF THE COLD TROUGH WILL BE WELL NORTH AND EAST OF
THE NORTHERN ROCKIES AND SNOW LEVELS WILL BE 6500 FEET AND
HIGHER.
BEYOND WARMING, THE LONGER TERM DOES NOT FAVOR PRECIPITATION UNTIL
POTENTIALLY SUNDAY. MODEL CLUSTER ANALYSIS IS SPLIT BETWEEN
FADING OR DEVELOPING HIGH PRESSURE 56% AND A TROUGH WITH
POSITIONAL AND TIMING DIFFERENCES 44%, MORE TO COME.
AVIATION
ONCE AGAIN NORTHWEST MONTANA AND ALONG THE CONTINENTAL
DIVIDE WILL SEE ISOLATED SHOWERS AND THUNDERSTORMS. BRIEF LOWERING
OF VISIBILITY AND A FEW STRIKES OF LIGHTNING WILL BE POSSIBLE.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FROST ADVISORY UNTIL 9 AM MDT TUESDAY FOR BITTERROOT/SAPPHIRE
MOUNTAINS...FLATHEAD/MISSION VALLEYS...LOWER CLARK FORK
REGION...MISSOULA/BITTERROOT VALLEYS.
ID...FROST ADVISORY UNTIL 9 AM MDT /8 AM PDT/ TUESDAY FOR EASTERN
LEMHI COUNTY...NORTHERN CLEARWATER MOUNTAINS...SOUTHERN
CLEARWATER MOUNTAINS.
FROST ADVISORY UNTIL 9 AM PDT TUESDAY FOR OROFINO/GRANGEVILLE
REGION.
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