178
FXUS65 KMSO 141825
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1225 PM MDT FRI AUG 14 2026
DISCUSSION
KEY MESSAGES:
- ROUNDS OF SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN,
THE POTENTIAL FOR FLASH FLOODING, AND GUSTY WINDS (MAINLY
WESTERN MONTANA) THROUGH EARLY THIS EVENING.
- WARMING, OVERALL DRYING THROUGH THE WEEKEND WITH AFTERNOON
CHANCES FOR SHOWERS AND THUNDERSTORMS.
HEAVY RAINFALL AND ISOLATED FLASH FLOODING REMAIN THE PRIMARY
OPERATIONAL CONCERNS TODAY. ONGOING MORNING SHOWERS AND EMBEDDED
THUNDERSTORMS ACROSS SOUTHWEST AND WEST-CENTRAL MONTANA HAVE
ALREADY PRODUCED RAIN RATES BETWEEN 0.25 AND 0.50 INCHES PER HOUR.
AS ATMOSPHERIC INSTABILITY BUILDS THROUGH THIS AFTERNOON, SLOW-
MOVING OR TRAINING THUNDERSTORMS WILL REDEVELOP ACROSS NORTH-
CENTRAL IDAHO AND PRIMARILY WESTERN MONTANA. WITH ABOVE-NORMAL
PRECIPITABLE WATER VALUES AND TRAINING STORM POTENTIAL, LOCALIZED
FLASH FLOODING AND SUBSEQUENT DEBRIS FLOW ACTIVITY REMAINS A
DISTINCT HAZARD ESPECIALLY IN AND DOWNSTREAM OF BURN SCARS, STEEP
TERRAIN, AND POOR-DRAINAGE URBAN LOCATIONS. ACTIVITY WILL PEAK
THROUGH LATE AFTERNOON BEFORE DIMINISHING AROUND 7:00 PM MDT.
DOWNBURST OUTFLOW WINDS REACHING UP TO 40-45 MPH AND SMALL HAIL
WILL ACCOMPANY THE STRONGER CELLS.
AN UPPER-LEVEL RIDGE BEGINS REBUILDING OVER THE WESTERN US THIS
WEEKEND, INITIATING A GRADUAL WARMING AND OVERALL DRYING TREND.
HOWEVER, PERSISTENT SOUTHWESTERLY FLOW ALOFT WILL CONTINUALLY
TRANSPORT MONSOONAL MOISTURE OUT OF THE GREAT BASIN AND INTO THE
REGION, MAINTAINING DAILY CHANCES FOR SCATTERED AFTERNOON SHOWERS
AND THUNDERSTORMS THROUGH EARLY NEXT WEEK.
ENSEMBLE GUIDANCE HAS INDICATED A RIDGE-FLATTING TROUGH PASSAGE
OUT OF CANADA IN THE TUESDAY TO WEDNESDAY TIME FRAME, WHICH COULD
PROMOTE MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES
INDEPENDENT OF THE DIURNAL THUNDERSTORM REGIME. THIS WEATHER
FEATURE WILL ALSO LIKELY PROMOTE AN INCREASE IN SURFACE WESTERLY
WIND SPEEDS.
REGIONAL WILDFIRE SMOKE WILL BEGIN RETURNING ALOFT IN THE COMING
DAYS, BUT SURFACE SMOKE CONCENTRATIONS ARE EXPECTED TO REMAIN
LIGHT AT THIS TIME.
HIGH AMOUNTS OF LOW-LEVEL MOISTURE FROM TODAY'S RAINFALL COMBINED
WITH OVERNIGHT DECOUPLING AND CLEARING SKIES WILL FAVOR FOG AND
LOW STRATUS FORMATION IN MOUNTAIN VALLEYS THROUGH THE OVERNIGHT
PERIOD INTO SATURDAY MORNING. GOOD TO EXCELLENT OVERNIGHT RELATIVE
HUMIDITIES ARE EXPECTED HELPING TO CURB FIRE ACTIVITY OVERNIGHT
AND SHORTENING BURN WINDOWS. DAILY THUNDERSTORM ACTIVITY WILL
INTRODUCE CONCERNS FOR NEW LIGHTNING STARTS OVER THE COMING DAYS.
AVIATION
HEAVY RAIN-BEARING SHOWERS AND THUNDERSTORMS (TSRA)
REMAIN THE MAIN HAZARD THROUGH ABOUT 15/0200Z. PASSING STORMS WILL
PRODUCE TEMPORARY MVFR/IFR VISIBILITY DROPS IN HEAVY DOWNPOURS.
BRIEF LOCALIZED ERRATIC OUTFLOW WIND GUSTS UP TO 35-40 KNOTS AND
SMALL HAIL ARE POSSIBLE WITH THE STRONGEST STORMS THAT DEVELOP.
RICH LOW-LEVEL MOISTURE FOLLOWING TODAY'S RAINFALL PAIRED WITH
LIGHT OVERNIGHT WINDS AND CLEARING SKIES WILL CREATE FAVORABLE
CONDITIONS FOR FOG AND LOW STRATUS DEVELOPMENT IN MOUNTAIN VALLEYS
AFTER 15/0600Z. IF FOG DOES DEVELOP, ANTICIPATE IT LASTING
THROUGH MID-MORNING ON SATURDAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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