880
FXUS65 KMSO 131852
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1252 PM MDT MON JUL 13 2026
DISCUSSION
KEY MESSAGES:
- A SURGE OF UPPER LEVEL MOISTURE INTO THE REGION IS CAUSING CLOUD
COVER, VIRGA, AND INCREASING HUMIDITY ACROSS THE REGION TODAY.
- THUNDERSTORMS THIS EVENING ARE FORECAST FOR SOUTHWEST MONTANA
THIS AFTERNOON INCLUDING SOUTHERN POWELL, GRANITE, DEER LODGE,
AND SILVER BOW COUNTIES.
- THUNDERSTORMS ARE IN THE FORECAST THROUGH THE WEEK FOR MUCH OF
WESTERN MONTANA AND PORTIONS OF CENTRAL IDAHO. STORMS WILL
CONTINUE IN SOUTHWEST MONTANA THROUGH THE WEEKEND.
UPPER LEVEL MOISTURE CONTINUES TO STREAM INTO THE REGION FROM THE
SOUTHWEST. THIS IS CAUSING CLOUD COVER ACROSS MUCH OF THE REGION,
AND VIRGA, WHICH IN TURN MOISTENS THE LOWER ELEVATIONS. AS A
RESULT, WE'VE SEEN QUITE AN INCREASE IN HUMIDITY WITH DEW POINTS
INCREASING INTO THE UPPER 40S AND LOW 50S ACROSS THE REGION. HIGH
RESOLUTION, SHORT TERM ENSEMBLES SHOW THUNDERSTORMS THIS
AFTERNOON MAINLY AFFECTING SOUTHERN POWELL, DEER LODGE, GRANITE,
AND SILVER BOW COUNTIES IN WESTERN MONTANA. THERE IS A MARGINAL
RISK FOR THESE STORMS TO CAUSE WIND GUSTS NEAR 60 MPH, BUT THE
HIGHER THE DEW POINTS GET THIS EVENING, THE LESS LIKELY THAT
BECOMES.
THE TREND CONTINUES TOMORROW WITH PRECIPITABLE WATER, WHICH IS A
MEASURE OF HOW MUCH WATER VAPOR IS AVAILABLE TO CONDENSE AND FALL
AS RAIN, RISING UP TO AROUND 1.5 INCHES. THIS IS AROUND 200 TO
250 PERCENT OF AVERAGE FOR THIS TIME OF YEAR. THIS WOULD BE VERY
ALARMING, EXCEPT THAT WHEN THERE'S THAT MUCH MOISTURE IT USUALLY
CLOUDS UP AND PREVENTS ENOUGH INSTABILITY FROM BUILDING UP FOR
STRONG STORMS. CURRENTLY ENSEMBLES ARE FORECASTING LIGHT TO
MODERATE RAIN SHOWERS EMBEDDED IN THE LARGER CLOUD SHIELD ACROSS
THE REGION.
THIS GENERAL PATTERN PERSISTS INTO NEXT WEEK. THE DETAILS WILL
DETERMINE WHICH AREAS SEE THUNDERSTORMS EACH DAY, WITH SOUTHWEST
MONTANA BEING THE MOST CONSISTENT AREA. BUT OVERALL, THE GENERAL
SOUTHWEST FLOW PATTERN WITH THUNDERSTORMS REMAINS THROUGH EARLY
NEXT WEEK.
AVIATION
EXPECT INCREASING CLOUD COVER AND CONTINUED VIRGA
TODAY UNDER A SOUTHWEST FLOW PATTERN. THE VIRGA IS EXPECTED TO
BLOSSOM INTO THUNDERSTORMS IN SOUTHWEST MONTANA THIS AFTERNOON.
CURRENTLY, HIGH RESOLUTION MODELS SHOW TERMINAL KBTM AS THE ONLY
ONE LIKELY TO BE IMPACTED BY THUNDERSTORMS. THERE IS A MARGINAL
CHANCE, AROUND 5% OF THUNDERSTORM WINDS AROUND 60MPH AFFECTING
KBTM THIS EVENING AND AGAIN TOMORROW EVENING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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