205
FXUS65 KTFX 241910
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
110 PM MDT WED JUN 24 2026
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS INCREASE IN COVERAGE THE NEXT FEW
AFTERNOONS.
- COOLER THIS WEEKEND INTO NEXT WEEK, PARTICULARLY ON SUNDAY.
- STILL SOME UNCERTAINTY WITH EXACTLY HOW FAR SNOW LEVELS FALL, BUT
THE RISK FOR MOUNTAIN SNOW REMAINS FOR SATURDAY NIGHT THROUGH
MONDAY MORNING.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
TRANSIENT UPPER LEVEL RIDGING BETWEEN BROAD TROUGHING TO THE EAST
AND STRONGER TROUGHING WELL OFF TO THE NORTHWEST OFF THE FAR
NORTHERN BC COASTLINE WILL BE THE INITIAL FEATURE DICTATING WEATHER
ACROSS THE REGION. ALTHOUGH THIS RIDGING IS IN PLACE, THERE STILL
LOOKS TO BE SUFFICIENT AFTERNOON HEATING TODAY TO RESULT IN SHOWERS
AND THUNDERSTORMS, MAINLY NEAR CENTRAL AND SOUTHWEST MONTANA
TERRAIN. THE OVERALL COMBINATION OF THE KINEMATICS AND
THERMODYNAMICS DOES NOT OFFER MUCH CONFIDENCE IN A STRONGER
THUNDERSTORM TODAY, THOUGH ONE CANNOT BE COMPLETELY RULED OUT.
THE UPPER LEVEL TROUGHING WELL OFF TO THE NORTHWEST GRADUALLY DRIFTS
SOUTHEAST THROUGH THE REMAINDER OF THE WEEK, WHICH WILL SLOWLY
INTRODUCE A MORE SOUTHWESTERLY FLOW ALOFT. SHOWERS AND THUNDERSTORMS
INCREASE IN COVERAGE ACROSS THE REGION AS A RESULT OF THIS MORE
FAVORABLY FORCING. THE ENVIRONMENT IS SPLIT FOR THURSDAY, WITH
BETTER INSTABILITY FURTHER NORTH AND MORE FAVORABLE SHEAR FURTHER
SOUTH. AT THIS TIME ORGANIZED STRONG TO SEVERE THUNDERSTORMS LOOK TO
BE ISOLATED AT BEST. SHOULD THERE BE ANY TREND IN A MORE FAVORABLE
DIRECTION IN PARAMETER SPACE, THE RISK FOR ORGANIZED STRONG TO
SEVERE THUNDERSTORMS WOULD INCREASE.
UPPER TROUGHING CONTINUES ITS APPROACH INTO FRIDAY, BRINGING
POTENTIAL FOR A COUPLE IMPACTS. THE FIRST WILL BE FOR ANOTHER ROUND
OF WIDESPREAD SHOWERS AND THUNDERSTORMS, PRIMARILY IN THE AFTERNOON
AND EVENING. AMPLE FORCING FROM THE APPROACHING TROUGHING WILL HAVE
NO ISSUE SUPPORTING SHOWER AND THUNDERSTORM ACTIVITY, BUT THICK
CLOUD COVER EARLY IN THE DAY AND INTO THE AFTERNOON RAISES QUESTIONS
WITH RESPECT TO JUST HOW MUCH DESTABILIZATION WILL OCCUR. AT THIS
TIME THE RISK FOR STRONGER THUNDERSTORMS APPEARS LOW, BUT SHOULD
INSTABILITY TREND HIGHER, THERE WOULD BE PLENTY OF SHEAR IN PLACE TO
SUPPORT STRONGER THUNDERSTORMS. TRENDS WILL CONTINUE TO BE
MONITORED.
THE OTHER CONCERN FOR FRIDAY WILL BE FOR BREEZY SOUTHWEST WINDS NEAR
THE IDAHO BORDER BETWEEN MONIDA PASS AND WEST YELLOWSTONE. A NARROW
MID-LEVEL JET LOOKS TO MOVES ACROSS THIS PORTION OF SOUTHWEST
MONTANA FRIDAY MORNING INTO THE AFTERNOON. WHILE THESE STRONGER WINDS
ALOFT TO LOOK TO AT LEAST BRIEFLY MIX TO THE SURFACE, THE OVERALL
MAGNITUDE OF WINDS AT THE SURFACE AS WELL AS THE DURATION OF THESE
WINDS IS QUESTIONABLE - AGAIN RELATED TO FORECAST CLOUD COVER ACROSS
THE REGION.
THE CORE OF THE UPPER LEVEL DISTURBANCE LOOKS TO BE OFF THE WA/OR
COASTLINE BY SATURDAY, KEEPING THE NORTHERN ROCKIES SQUARELY WITHIN
A PERSISTENT SOUTHWESTERLY FLOW ALOFT. GIVEN THE AMPLE FORCING
ASSOCIATED WITH THE NEARBY TROUGHING, SHOWERS AND THUNDERSTORMS WILL
BE FAIR GAME BEGINNING QUITE EARLY IN THE DAY ACROSS SOUTHWEST
MONTANA, SPREADING NORTHEASTWARD WITH TIME INTO SATURDAY AFTERNOON.
BY SATURDAY EVENING THE CORE OF THE UPPER DISTURBANCE BEGINS
TRACKING EASTWARD, MOVING SOMEWHERE OVER THE NORTHERN ROCKIES INTO
SUNDAY. A MORE STRATIFORM TYPE OF PRECIPITATION ENSUES THEREAFTER,
WITH GREATEST AMOUNTS GENERALLY ON THE NORTHWEST SIDE OF THE CORE OF
THE DISTURBANCE. SNOW LEVELS LOOK TO DROP LOWEST WHERE THE LOW
TRACKS, WHICH IS STILL UNCERTAIN. THOSE WITH RECREATION PLANS THIS
WEEKEND IN THE TERRAIN SHOULD BE AWARE OF THE RISK FOR THE COLDER
CONDITIONS AND RISK FOR SNOW.
BY EARLY NEXT WEEK THE DISTURBANCE MOVES NORTHEAST, BUT LINGERING
TROUGHING HANGS AROUND. THIS LOOKS TO KEEP TEMPERATURES ON THE
COOLER SIDE OF AVERAGE WITH CONTINUED OPPORTUNITIES FOR
PRECIPITATION INTO MID-WEEK. -AM
- FORECAST CONFIDENCE & SCENARIOS:
GUSTY WINDS ON FRIDAY...
ANOMALOUS, WITH RESPECT TO LATE JUNE CLIMATOLOGY, SOUTHERLY H700
WINDS OF 30-40KTS WILL OVERSPREAD SOUTHWEST MONTANA FROM THE LATE
MORNING THROUGH EARLY EVENING HOURS. THIS TIMING COMBINED WITH THE
FLOW ORIENTATION, WITH RESPECT THE NORTH-SOUTH VALLEYS AND MOUNTAIN
PASSES ALONG THE IDAHO BORDER, WILL HELP TO SUPPORT A PERIOD OF
STRONG AND GUSTY WINDS DUE TO MIXING AND TERRAIN FUNNELING. LATEST
NBM5.0 PROBABILITIES SUPPORT A 50-80% CHANCE THAT GUSTS EXCEED 40
MPH ALONG AND SOUTH OF A DILLON, TO ENNIS, TO BIG SKY LINE, WITH
EVEN A 30-60% CHANCE THAT GUSTS EXCEED 50 MPH. FURTHERMORE THERE IS
EVEN A 20% CHANCE THAT SUSTAINED WINDS WITHIN THE MADISON VALLEY
REACH 40 MPH FOR A PERIOD OF TIME FROM LATE FRIDAY MORNING THROUGH
THE EARLY EVENING HOURS. WHILE THESE PROBABILITIES AND DETERMINISTIC
GUIDANCE DO NOT CURRENTLY SUPPORT HIGH WIND HIGHLIGHTS IT WILL BE
NONE-THE-LESS WINDY ON FRIDAY, WHICH WILL CAUSE SOME DIFFICULTIES
FOR THOSE OPERATING HIGH PROFILE VEHICLES.
SHOWERS AND THUNDERSTORMS FROM WEDNESDAY THROUGH FRIDAY...
MARGINAL INSTABILITY AND SHEAR THROUGHOUT THE TIMEFRAME WILL HELP TO
LIMIT MOST CONVECTION TO THE GARDEN VARIETY TYPE, WITH GUSTY WINDS
OF 45-55 MPH AND HAIL UP TO THE SIZE OF NICKLES; HOWEVER, A FEW
MARGINALLY SEVERE THUNDERSTORMS PRODUCING WIND GUSTS IN EXCESS OF 60
MPH AND HAIL LARGER THAN QUARTERS CAN'T BE RULED OUT, ESPECIALLY ON
THURSDAY ACROSS SOUTHWEST MONTANA. ADDITIONALLY, WITH PRECIPITABLE
WATER (PWATS) CLIMBING TO BETWEEN 0.5" TO 1" BY THURSDAY AND FRIDAY,
WHICH IS 1 TO NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL PER NAEFS
ANALYSIS, LOCALIZED HEAVY RAINFALL WILL BECOME POSSIBLE. THE MAIN
CONCERN FROM THESE HEAVIER BURSTS OF RAIN WILL BE DEBRIS
FLOWS/FLOODING ACROSS RECENT BURNS SCARS LIKE THE HORSE GULCH AREA.
WIDESPREAD PRECIPITATION THIS WEEKEND THROUGH MONDAY...
CLIMATE ANOMALY INDICATORS LIKE THE ECMWF EFIS CONTINUE TO SUPPORT
THE POTENTIAL FOR A CLIMATOLOGICALLY UNUSUAL PRECIPITATION EVENT FOR
MUCH OF SOUTHWEST MONTANA AND PORTIONS OF NORTH CENTRAL MONTANA
THROUGHOUT THE TIMEFRAME. THIS IS SIGNIFICANT GIVEN THAT FACT THAT
JUNE IS CLIMATOLOGICALLY ONE OF IF NOT THE WETTEST MONTHS OF THE
YEAR FOR THESE AREAS. LATEST NBM5.0 PROBABILITIES FOR LIQUID
EQUIVALENT AMOUNTS OF 1" OR GREATER FROM SATURDAY MORNING THROUGH
MONDAY NIGHT RANGE FROM A 40-80% CHANCE ACROSS ALL OF SOUTHWEST
THROUGH NORTH CENTRAL MONTANA, WITH A 20-50% CHANCE THAT VALUES
EXCEED 2" ACROSS THE GLACIER NATIONAL PARK REGION AND WITHIN AN AREA
FROM EAST OF THE I-15 CORRIDOR AND WEST OF THE US HWY 89 CORRIDOR
ACROSS SOUTHWEST AND CENTRAL MONTANA (I.E. ENNIS, BOZEMAN, AND WHITE
SULPHUR SPRINGS AREAS). LOWERING SNOW LEVELS THIS WEEKEND AND EARLY
NEXT WEEK WILL ALSO HELP TO SUPPORT RAIN CHANGING OVER TO SNOW IN
THE MOUNTAINS, WITH A 30-60% CHANCE THAT SNOWFALL AMOUNTS EXCEED 4"
AT ELEVATIONS OF 7000FT OR HIGHER ACROSS SOUTHWEST MONTANA. THE
COMBINATION OF WET AND RAW CONDITIONS WILL LEAD TO AN INCREASED RISK
OF HYPOTHERMIA FOR THOSE RECREATING IN THE BACKCOUNTRY AT ANY
ELEVATION, ESPECIALLY THOSE RECREATING ABOVE 7000FT. - MOLDAN
AVIATION
24/18Z TAF PERIOD
THE PRIMARY CONCERN THIS TAF PERIOD WILL BE FOR AFTERNOON SHOWERS
AND THUNDERSTORMS, MAINLY NEAR TERRAIN IN CENTRAL AND SOUTHWEST
MONTANA. PROB30S WERE ADDED WHERE CONFIDENCE WAS GREATEST IN SHOWERS
OR THUNDERSTORMS BEING AROUND THIS AFTERNOON. OTHERWISE ATTENTION
TURNS TO TOMORROW WHERE SHOWERS WILL BE AROUND BY EARLY MORNING,
MAINLY ACROSS CENTRAL AND SOUTHWEST MONTANA. ADDITIONAL SHOWERS AND
THUNDERSTORMS DEVELOP BY LATE MORNING INTO EARLY AFTERNOON ACROSS
THE ENTIRE REGION. -AM
PRELIMINARY POINT TEMPS/POPS
GTF 49 75 52 74 / 10 70 20 80
CTB 47 73 50 68 / 0 60 30 80
HLN 53 77 55 73 / 40 70 40 90
BZN 47 76 50 76 / 20 70 30 70
WYS 40 70 42 70 / 40 80 30 50
DLN 47 77 51 71 / 30 50 20 60
HVR 49 78 50 78 / 0 30 30 70
LWT 44 70 46 74 / 10 70 40 80
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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