326
FXUS65 KMSO 170816
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
216 AM MDT FRI JUL 17 2026
DISCUSSION
KEY MESSAGES:
- STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING,
BRINGING THE THREAT OF STRONG WINDS, LARGE HAIL, AND HEAVY RAIN.
- TRENDING DRIER AND BREEZY THIS WEEKEND. ELEVATED FIRE WEATHER BY
SUNDAY FROM HOT, DRY, AND BREEZY CONDITIONS.
- THUNDERSTORMS RETURN BY TUESDAY NEXT WEEK WITH NEXT MONSOON
MOISTURE SURGE.
SUBTROPICAL MOISTURE ASSOCIATED WITH THE NORTH AMERICAN MONSOON
CONTINUES TO STREAM NORTHWARD AS SEEN IN GOES WATER VAPOR IMAGERY
THIS MORNING. THIS SURGE OF MOISTURE WILL PEAK THIS AFTERNOON,
WITH PRECIPITABLE WATER VALUES RANGING FROM 1.00-1.25 INCHES, OR
200-225% OF NORMAL. WITH ABUNDANT MOISTURE IN PLACE AND A WARM
AIRMASS OVERHEAD, MODEST INSTABILITY (1000-1500 J/KG) WILL FUEL
ANOTHER ROUND OF SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON
AND EVENING. HIGH-RESOLUTION MODELS POINT TOWARDS CONVECTION
INITIATING ACROSS THE HIGHER TERRAIN OF CENTRAL IDAHO BY EARLY
AFTERNOON, WITH STORMS MOVING SOUTH TO NORTH THROUGH THE EVENING.
THE STORM PREDICTION CENTER HAS PLACED THE REGION UNDER A MARGINAL
THREAT FOR SEVERE THUNDERSTORMS, WITH ANY LOCATION HAVING A 5%
CHANCE FOR LARGE HAIL (1.00-1.50 INCH IN DIAMETER) AND DAMAGING
WINDS (60 MPH OR GREATER). ATMOSPHERIC INSTABILITY AND WIND SHEAR
PROFILES SUGGEST MULTICELLULAR STORM CLUSTERS, WITH DISCRETE
STORMS GROWING UPSCALE INTO STORM COMPLEXES BY THE EVENING HOURS
AS THEY TRACK NORTH INTO WEST-CENTRAL AND NORTHWEST MONTANA.
STORMS WILL ALSO BE CAPABLE OF PRODUCING HEAVY RAINFALL. OUR
REGION IS UNDER A MARGINAL RISK (5% CHANCE FOR ANY GIVEN LOCATION)
FOR EXCESSIVE RAINFALL ACROSS FLOOD PRONE AREAS, INCLUDING RECENT
BURN SCARS.
LOOKING AHEAD TO THE WEEKEND, THE FOCUS FOR SHOWERS AND
THUNDERSTORMS SHIFTS INTO LEMHI COUNTY, ID AND SOUTHWEST MONTANA.
BY SUNDAY, DRIER AIR WILL MOVE OVERHEAD, WITH MOST LOCATIONS
SEEING WARM AND DRY CONDITIONS. HOT, DRY, AND BREEZY CONDITIONS ON
SUNDAY WILL LEAD TO ELEVATED FIRE WEATHER CONDITIONS.
GLOBAL ENSEMBLES SUGGEST THE NEXT SURGE OF MONSOON MOISTURE WILL
ARRIVE BY THE MIDDLE OF NEXT WEEK (TUESDAY INTO THURSDAY). CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL TREND HIGHER EACH DAY AS
PRECIPITABLE WATER VALUES REACH OVER ONE INCH.
AVIATION
NOCTURNAL THUNDERSTORMS CONTINUE TO MOVE NORTHWARD
ACROSS THE HIGHER TERRAIN OF THE IDAHO/MONTANA BORDER. DISTANT
LIGHTNING WILL BE SEEN FROM KMSO THROUGH 17/1000Z, WITH
THUNDERSTORM ACTIVITY MOVING THROUGH FAR NORTHWEST MONTANA INTO
17/1200Z. ANOTHER ROUND STRONG TO ISOLATED SEVERE THUNDERSTORMS
WILL IMPACT THE REGION THIS AFTERNOON AND EVENING AS MONSOON
MOISTURE CONTINUES TO SURGE NORTHWARD INTO THE AIRSPACE. HIGH-
RESOLUTION MODELS POINT TOWARDS CONVECTION INITIATION ACROSS
MOUNTAIN AREAS OF NORTH-CENTRAL IDAHO BY 17/1900Z, WITH STORMS
TRACKING NORTHWARD NEAR KSMN/KBTM/KHRF BETWEEN 17/2100-2300.
ATMOSPHERIC INSTABILITY AND WIND SHEAR PROFILES SUGGEST STORMS
WILL GROW UPSCALE INTO LARGE COMPLEXES, ESPECIALLY AS THEY TRACK
NORTHWARD INTO WEST-CENTRAL AND NORTHWEST MONTANA. THESE STORMS
WILL BRING A HIGHER RISK OF STRONG WINDS, PARTICULARLY FOR KMSO
AND KGPI DURING THE EVENING HOURS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...
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