436
FXUS65 KMSO 030934
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
334 AM MDT FRI JUL 3 2026
DISCUSSION
KEY MESSAGES:
- ISOLATED THUNDERSTORMS LEMHI COUNTY, ID AND SOUTHWEST MONTANA
TODAY.
- BREEZY JULY 4TH BUT GOOD FIREWORKS WEATHER: HOT AND BREEZY
CONDITIONS WILL CAUSE AREA LAKES TO BE CHOPPY, WINDS DECOUPLE
BY EVENING, OFFERING EXCELLENT CONDITIONS FOR FIREWORKS AND
POTENTIAL AURORA VIEWING.
- HEAVY RAIN THREAT MONDAY: DEEP MOISTURE AND A STRONGER
DISTURBANCE BRING AN INCREASING POTENTIAL FOR MORE ORGANIZED
STORMS AND HEAVY RAIN/LOCALIZED FLASH FLOODING, GUSTY WINDS,
LIGHTNING AND SMALL HAIL.
TODAY: A WEAK MID-LEVEL SHORTWAVE TRACKING ACROSS THE NORTHERN
ROCKIES COULD PROVIDE JUST ENOUGH LIFT TO WEAKEN THE CAPPING
INVERSION THAT SUPPRESSED VERTICAL SHOWER GROWTH YESTERDAY. HIGHS
WILL TREND A COUPLE OF DEGREES WARMER THAN YESTERDAY. CONVECTIVE
PARAMETERS (INCLUDING MORE FAVORABLE LIFTED INDICES) SUGGEST A
SLIGHTLY BETTER ENVIRONMENT FOR ISOLATED TERRAIN-INDUCED
CONVECTION. THE HIGH RESOLUTION MODELS, ECMWF AND GFS BOTH LEAN
TOWARD ISOLATED STORM DEVELOPMENT OVER LEMHI COUNTY, THE BUTTE
AREA, AND SOUTHWEST MONTANA.
SATURDAY (JULY 4TH): A STRONGER, PROGRESSIVE TROUGH MOVING
THROUGH SOUTHERN BRITISH COLUMBIA WILL FLATTEN THE RIDGE A BIT
CAUSING AN UPTICK IN WESTERLY WINDS.
WINDS & LAKE IMPACTS: THE STRONGER WINDS ALOFT OVER NORTHWEST
MONTANA PRESENTS A GOOD SETUP FOR AFTERNOON MOMENTUM TRANSFER DOWN
TO THE SURFACE. HOWEVER, GIVEN CURRENT WATER TEMPERATURES ON
FLATHEAD LAKE SITTING IN THE LOWER 60S FAHRENHEIT, THIS WILL
LIMIT DEEP MIXING DIRECTLY OVER THE WATER AND KEEP WINDS BELOW
LAKE WIND ADVISORY CRITERIA OVER THE OPEN WATER. THE WESTERN
SHORES (SUCH AS BIG ARM) AND IMMEDIATELY ADJACENT TERRAIN COULD
SEE BREEZY CONDITIONS WITH GUSTS OF 20-25 MPH.
EVENING HOLIDAY OUTLOOK: AS FOR ANY PRECIPITATION, THERE COULD BE
A ROGUE, BRIEF SHOWER OVER THE CLEARWATER MOUNTAINS. HOWEVER,
HIGH PRESSURE BUILDING IN FOR THE EVENING WILL ENSURE CLEAR SKIES
AND DECOUPLING WINDS BY FIREWORKS TIME.
SPACE WEATHER NOTE: THE SPACE WEATHER PREDICTION CENTER WROTE IN
THEIR LATEST AURORA FORECAST THAT THERE COULD BE A CHANCE FOR
AURORAS (MODERATE GEOMAGNETIC STORMING) THROUGH JULY 4TH. RIGHT
NOW, THE SKIES LOOK TO CLEAR SATURDAY NIGHT.
SUNDAY: ZONAL FLOW ON THE BACKSIDE OF THE DEPARTING CANADIAN
TROUGH KEEPS AFTERNOON CONDITIONS BREEZY, WITH LOCALIZED GUSTS UP
TO 25 MPH. VALLEY TEMPERATURES WILL CONTINUE TO RUN ABOUT 5 TO 10
DEGREES ABOVE SEASONAL AVERAGES. MONSOONAL MOISTURE CREEPING INTO
THE SOUTHERN TIER MAY BRING A RETURN OF ISOLATED THUNDERSTORM
CHANCES TO LEMHI COUNTY AND SOUTHWEST MONTANA.
SUNDAY NIGHT: HIGH PRESSURE DROPPING EAST OF THE CONTINENTAL
DIVIDE WILL SET UP A TIGHTENING SURFACE PRESSURE GRADIENT,
INDUCING A SHIFT TO BREEZY EASTERLY GAP WINDS OVER THE DIVIDE AND
INTO WESTERN VALLEYS OVERNIGHT.
LONG TERM (MONDAY THROUGH THURSDAY):
MONDAY: THE POTENTIAL FOR A CONVECTIVE EVENT IS IALSO GUSTY WINDS COULD BE AN ADDITIONAL
THREAT. NCREASING AS SUBTROPICAL MOISTURE WILL SURGE INTO THE
REGION, PUSHING PRECIPITABLE WATER (PWAT) VALUES WELL ABOVE NORMAL
(+2 TO +3 STANDARD DEVIATIONS). AN EMBEDDED SHORTWAVE MOVING
THROUGH THIS MOIST FLOW, COMBINED WITH 30-35 KNOTS OF SHEAR AND
HOT TEMPERATURES, PROVIDES A FAVORABLE ENVIRONMENT FOR ORGANIZED,
STRONG THUNDERSTORMS. MAIN THREATS WILL BE LIGHTNING, GUSTY WINDS,
HAIL AND HEAVY RAINFALL CAPABLE OF LOCALIZED FLASH FLOODING.
CLOUD COVER REMAINS A CAVEAT, WHICH COULD SEVERELY LIMIT
DESTABILIZATION. MODEL TIMING DIFFERENCES ALSO NEED TO BE IRONED
OUT.
TUESDAY THROUGH THURSDAY: SHOWER AND THUNDERSTORM ACTIVITY WILL
LIKELY LINGER INTO TUESDAY BEFORE THE UPPER RIDGE BEGINS TO
FLATTEN MID-WEEK. MULTI-MODEL ENSEMBLE CLUSTERS SUPPORT(57%) A
TRANSITION BACK TO A MORE PROGRESSIVE WESTERLY FLOW(BREEZY & WARM)
PATTERN BY WEDNESDAY AND THURSDAY.
AVIATION
VFR CONDITIONS WILL DOMINATE THE REGION TODAY. A WEAK
PASSING DISTURBANCE WILL BRING A SLIGHT CHANCE OF ISOLATED
AFTERNOON SHOWERS OR THUNDERSTORMS, WITH KBTM POSSIBLY IMPACTED.
OTHERWISE, DIURNAL WIND PATTERNS WILL PREVAIL WITH SPEEDS
REMAINING UNDER 10 KNOTS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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