432
FXUS65 KMSO 060858
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
258 AM MDT MON JUL 6 2026
DISCUSSION
KEY MESSAGES:
- LOCALIZED HEAVY RAINFALL/GUSTY OUTFLOW WIND THREAT TODAY WITH
SHOWERS AND STORMS.
- WARMEST TEMPERATURES SO FAR THIS SUMMER POSSIBLE THIS WEEKEND
INTO EARLY NEXT WEEK
THE MOST IMPACTFUL WEATHER OF THE WEEK ARRIVES TODAY AS A ROBUST
SURGE OF SUBTROPICAL MOISTURE MOVES INTO THE REGION. COMBINED
WITH AFTERNOON HEATING, THIS MOISTURE WILL SPARK ORGANIZED
THUNDERSTORMS ACROSS NORTH-CENTRAL IDAHO AND WEST-CENTRAL INTO
SOUTHWEST MONTANA. BECAUSE THESE STORMS ARE ANTICIPATED TO BE
SLOW-MOVING, RAINFALL COULD STACK UP SIGNIFICANTLY IN A SHORT
PERIOD OF TIME. PRIMARY HAZARDS INCLUDE FREQUENT LIGHTNING CAPABLE
OF IGNITING NEW WILDFIRES IN DRY FUELS, AS WELL AS ERRATIC WIND
GUSTS OF 40 TO 50 MPH. NOTABLY, HIGH-RESOLUTION MODELS SHOW THESE
WINDS TRACKING NORTH THROUGH THE BITTERROOT AND MISSOULA VALLEYS
BETWEEN 5:00 PM AND 7:00 PM WITH GUSTS UP TO 40 MPH POSSIBLE.
ADDITIONALLY, HEAVY RAINFALL RATES OF 0.50 TO 0.75 INCHES PER HOUR
WILL INTRODUCE A LOCALIZED RISK FOR FLASH FLOODING AND DEBRIS
FLOWS, PARTICULARLY OVER RECENT BURN SCARS.
WHILE THICK MORNING CLOUD COVER MAY INITIALLY DELAY DAYTIME
STORM DEVELOPMENT, STRONG ATMOSPHERIC FORCING IS EXPECTED TO
OVERCOME THIS BY THE AFTERNOON. SHOWERS AND ISOLATED THUNDERSTORMS
MAY LINGER OVERNIGHT, PARTICULARLY ACROSS NORTHWEST MONTANA AND
ALONG THE CONTINENTAL DIVIDE. BY TUESDAY, LOWER ELEVATIONS WILL
BEGIN TO DRY OUT, BUT LINGERING MID-LEVEL MOISTURE WILL TRIGGER A
SECOND ROUND OF SCATTERED AFTERNOON THUNDERSTORMS. THIS ACTIVITY
WILL BE FOCUSED PRIMARILY FROM INTERSTATE 90 SOUTHWARD AND ALONG
THE CONTINENTAL DIVIDE.
WEDNESDAY THROUGH FRIDAY, THE REGION TRANSITIONS BACK TO A CLASSIC
SUMMER PATTERN. EXPECT WARM, DRY CONDITIONS WITH BREEZY WESTERLY
AFTERNOON WINDS. ANY ISOLATED, TERRAIN-DRIVEN AFTERNOON
THUNDERSTORMS WILL BE LARGELY RESTRICTED TO THE MOUNTAINS OF
SOUTHWEST MONTANA.
LOOKING AHEAD TO NEXT WEEKEND AND INTO MID-JULY, FORECAST MODELS
INDICATE THAT A STRONG RIDGE OF HIGH PRESSURE CURRENTLY OVER THE
DESERT SOUTHWEST WILL EXPAND NORTHWARD. WHILE THE RIDGE'S EXACT
PLACEMENT REMAINS UNCERTAIN, THE PREVAILING TREND STRONGLY FAVORS
A SHIFT TOWARD WELL ABOVE NORMAL TEMPERATURES. AS THIS PROLONGED
HEAT BUILDS LATE IN THE WEEK AND THROUGH THE WEEKEND, THE RISK FOR
HEAT-RELATED ILLNESSES WILL INCREASE. THIS WILL BE ESPECIALLY
TRUE FOR VULNERABLE POPULATIONS AND THOSE RECREATING OUTDOORS
WITHOUT ADEQUATE HYDRATION AND SHADE. FORECAST MODELS ALSO SUGGEST
THIS HIGH-PRESSURE SETUP COULD PERIODICALLY DRAW MOISTURE UP FROM
THE SOUTHWEST BEGINNING AROUND JULY 13TH OR 14TH, POTENTIALLY
TRIGGERING A RETURN TO DAILY THUNDERSTORM ACTIVITY.
AVIATION
INCREASING CLOUD COVER AND SHOWERS MAY LOCALLY OBSCURE TERRAIN
THIS MORNING, MAINLY SOUTH OF INTERSTATE 90. A ROBUST INFLUX OF
SUBTROPICAL MOISTURE WILL SPARK ORGANIZED, SLOW-MOVING
THUNDERSTORMS AFTER 20Z ACROSS SOUTHWEST/WEST-CENTRAL MONTANA AND
NORTH-CENTRAL IDAHO. TERMINALS DIRECTLY IMPACTED BY THESE STORMS
CAN EXPECT BRIEF MVFR/IFR CONDITIONS IN HEAVY DOWNPOURS, ALONG
WITH FREQUENT LIGHTNING AND TERRAIN OBSCURATION. ERRATIC
CONVECTIVE OUTFLOW GUSTS OF 35 TO 45 KNOTS ARE POSSIBLE. HIGH-
RESOLUTION GUIDANCE SPECIFICALLY HIGHLIGHTS A SOUTHERLY WIND SURGE
TRACKING NORTH THROUGH THE BITTERROOT AND MISSOULA VALLEYS
(DIRECTLY IMPACTING KMSO) BETWEEN 23Z AND 01Z, WITH GUSTS UP TO 35
KNOTS. SHOWERS AND ISOLATED THUNDERSTORMS WILL LINGER OVERNIGHT,
PARTICULARLY ACROSS NORTHWEST MONTANA (KGPI) AND ALONG THE
CONTINENTAL DIVIDE, BEFORE A SECOND ROUND OF SCATTERED AFTERNOON
THUNDERSTORMS DEVELOPS ON TUESDAY, FOCUSING PRIMARILY FROM
INTERSTATE 90 SOUTHWARD.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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