724
FXUS65 KMSO 161813
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1213 PM MDT THU JUL 16 2026
DISCUSSION
KEY MESSAGES:
- SCATTERED STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING, WITH STRONG WINDS, LARGE HAIL, AND HEAVY RAIN.
- ANOTHER ROUND OF SCATTERED STRONG TO SEVERE STORMS POSSIBLE
FRIDAY AFTERNOON AND EVENING
- TRENDING DRIER AND BREEZY THIS WEEKEND, THUNDERSTORMS RETURNING
BY TUESDAY NEXT WEEK
THE CONCERN FOR STRONG TO SEVERE THUNDERSTORMS REMAINS THIS
AFTERNOON AND EVENING ACROSS MUCH OF WESTERN MONTANA AND NORTH
CENTRAL IDAHO. HIGH RESOLUTION MODELS SHOW TWO MAIN AREAS OF
THUNDERSTORMS WITH SLIGHTLY DIFFERENT TIMING AND THREATS.
THUNDERSTORMS IN SOUTHWEST AND WEST-CENTRAL MONTANA WILL LIKELY
FORM ON THE EARLIER SIDE, AS EARLY AS 1PM, AND LINGER THROUGH
ROUGHLY 10PM. THESE STORMS WILL LARGELY FORM ON THE TERRAIN
INITIALLY BUT MAY SPREAD INTO VALLEY LOCATIONS TOWARDS EARLY
EVENING. THE BIGGER THREAT WITH THESE STORMS WILL BE LARGE HAIL
(QUARTER SIZED OR BIGGER) AND HEAVY RAINFALL. SEVERE WIND GUSTS
CAN'T BE COMPLETELY RULED OUT, BUT LACK OF STRONG FORCING ALOFT
AND OVERALL SLOWER STORM MOTIONS FAVORS GUSTS MORE IN THE 40 TO 50
MPH RANGE.
THUNDERSTORMS IN NORTHWEST MONTANA AND NORTH CENTRAL IDAHO WILL
LIKELY FORM LATER IN THE EVENING AND CONTINUE INTO THE OVERNIGHT
TIMEFRAME, GENERALLY 7PM AND 1AM MDT. THESE STORMS WILL BE DRIVEN
BY BETTER FORCING ALOFT, WITH LIGHTNING ALREADY OCCURRING
UPSTREAM IN EASTERN WASHINGTON/OREGON. THESE STORMS MAY POSE MORE
OF A WIND THREAT WITH THE POTENTIAL FOR UPSTREAM CONVECTION TO
FORM INTO MORE OF A LINE AS IT MOVES INTO NORTHWEST MONTANA,
MEANING WIND THREATS COULD BE MORE WIDESPREAD. WIND GUSTS 58 MPH
OR HIGHER ARE POSSIBLE WITH THE STRONGER STORMS. HEAVY RAIN AND
HAIL WILL ALSO BE A CONCERN.
FRIDAY, THE UPPER LEVEL PATTERN CHANGES VERY LITTLE. AN ADDITIONAL
SURGE OF MONSOONAL MOISTURE BRINGS ALREADY ELEVATED ATMOSPHERIC
MOISTURE VALUES EVEN HIGHER (PRECIPITABLE WATER VALUES GREATER
THAN 1 INCH). HIGH RESOLUTION MODELS ARE AGAIN FAVORING STRONG TO
SEVERE STORMS DEVELOPING IN THIS ENVIRONMENT. SOME QUESTIONS
REMAIN HOWEVER IN TERMS OF CLOUD COVER AND HOW THAT MAY IMPACT
HEATING AND THUS INSTABILITY BY THE AFTERNOON. IF CLOUD COVER DOES
NOT FILL IN TOMORROW MORNING, THUNDERSTORMS THREATS OF STRONG
OUTFLOW WINDS, HAIL AND VERY HEAVY RAINFALL WILL AGAIN BE A
CONCERN. DEBRIS FLOW IN FLOOD PRONE AREAS OR RECENT BURN SCARS
WILL BE A LARGER CONCERN AS WELL DUE TO THE HIGHER MOISTURE
CONTENT AND LOCATION OF STRONGER CONVECTION CLOSER TO REGIONAL
FLOOD PRONE AREAS IN SOUTHWEST MONTANA AND NORTH CENTRAL IDAHO.
LOOKING AHEAD TO THE WEEKEND, THE FOCUS FOR SHOWERS AND
THUNDERSTORMS SHIFTS INTO LEMHI COUNTY, ID AND SOUTHWEST MONTANA.
THE REST OF THE AREA WILL REMAIN WARM AND DRY. THIS CHANGE WILL
BE DRIVEN BY A WESTERLY FLOW ALOFT, WITH ATMOSPHERIC INSTABILITY
DECREASING FOR MANY AREAS. BREEZY WINDS WILL DEVELOP AS WELL,
PARTICULARLY ACROSS NORTHWEST MONTANA.
AVIATION
A MONSOON SURGE FROM THE SOUTH-SOUTHWEST HAS ATMOSPHERIC
MOISTURE RUNNING WELL ABOVE NORMAL ACROSS THE REGION. PLENTY OF
ATMOSPHERIC INSTABILITY WILL LEAD TO THUNDERSTORMS INITIATING OFF
THE TERRAIN OF CENTRAL IDAHO AND NORTHEAST OREGON. BETWEEN
16/1800-2000Z, WITH STORMS MOVING NORTHEASTWARD THROUGH THE
EVENING. INCREASING SOUTH-SOUTHWEST WINDS ALOFT WILL PROVIDE
SUFFICIENT WIND SHEAR TO ORGANIZE THUNDERSTORMS, WITH A 5-15%
CHANCE FOR SEVERE THUNDERSTORMS ACROSS THE REGION. PRIMARY STORM
THREATS INCLUDE LARGE HAIL (1 INCH IN DIAMETER OR GREATER), STRONG
WINDS (50-60KTS), AND HEAVY RAIN. HIGH RESOLUTION MODELS CONTINUE
TO HINT AT STORMS CONGEALING INTO A LINE THIS EVENING ACROSS
NORTHWEST MONTANA WHICH COULD BRING MORE WIDESPREAD STRONG WINDS.
ELEVATED INSTABILITY REMAINS ACROSS THE REGION OVERNIGHT WITH
SOME FORCING ACROSS NORTHWEST MONTANA, THUS A FEW THUNDERSTORMS
MAY POP UP DURING THE EARLY MORNING HOURS. VALLEY LOCATIONS THAT
EXPERIENCE RAIN TODAY WILL HAVE THE POTENTIAL FOR PATCHY FOG ON
FRIDAY MORNING.
THERE IS SOME CONCERN WITH CLOUD COVER LIMITING INSTABILITY ON
FRIDAY BUT MOST GUIDANCE SHOWS ENOUGH CLEARING ON FRIDAY MORNING
TO ALLOW FOR ANOTHER ROUND OF THUNDERSTORMS ON FRIDAY AFTERNOON
AND EVENING. GUSTY OUTFLOW WINDS ARE A CONCERN ONCE AGAIN WITH
HIGH RESOLUTION MODELS TRENDING TOWARD A WAVE OF STRONG OUTFLOW
WINDS ORIGINATING IN THE BITTERROOT VALLEY MID AFTERNOON, THEN
SPREADING NORTHWARD THROUGH THE EVENING HOURS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page