422
FXUS65 KTFX 012314
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
514 PM MDT WED JUL 1 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- DAILY CHANCES FOR SCATTERED SHOWERS AND THUNDERSTORMS THROUGH
FRIDAY WITH A CHANCE THAT A COUPLE MAY BECOME SEVERE.
- CONCERN FOR FLASH FLOODING ACROSS PORTIONS OF SOUTHWEST AND
CENTRAL MONTANA THROUGH THIS EVENING.
- DRIER, WARMER, AND BREEZY CONDITIONS EXPECTED OVER THE HOLIDAY
WEEKEND.
DISCUSSION
/ISSUED 256 PM MDT WED JUL 1 2026/
- METEOROLOGICAL OVERVIEW:
SCATTERED THUNDERSTORMS ARE ALREADY UNDERWAY ACROSS SOUTHWEST
MONTANA WITH GUSTS UP TO 45 MPH OBSERVED. THESE THUNDERSTORMS WILL
SLOWLY BECOME MORE NUMEROUS INTO CENTRAL MONTANA AS THE DAY
PROGRESSES WITH THE MAIN THREATS BEING STRONG WINDS, HAIL, HEAVY
DOWNPOURS, AND CLOUD TO GROUND LIGHTNING. A COUPLE STORMS MAY
BECOME SEVERE BUT THE LIMITING FACTOR THIS AFTERNOON WILL BE THE
LACK OF SHEAR ACROSS THE REGION. WITH SHEAR TURNING OUT TO BE LESS
THAN 20KTS ACROSS A GOOD PORTION OF THE REGION, STORM MOTION IS
EXPECTED TO BE ON THE SLOWER SIDE WHICH WILL INCREASE THE
POTENTIAL FOR FLASH FLOODING, ESPECIALLY IF THE THUNDERSTORMS
START TO TRAIN.
SIMILAR CONDITIONS PREVAIL ON THURSDAY AND FRIDAY WITH WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS, BUT THERE WILL BE A LACK OF A
DEFINED SHORTWAVE ON THURSDAY AND ON FRIDAY THE SHORTWAVE
POSITIONING LOOKS TO BE A LITTLE TOO FAR EAST FOR WIDESPREAD
ACTIVITY. FLAT RIDGING STARTS TO BUILD IN AND BRING WARMER
TEMPERATURES AND DRIER CONDITIONS FOR THE HOLIDAY WEEKEND;
HOWEVER, A MID-LEVEL TROUGH PASSING NORTH OF THE CANADIAN BORDER
LOOKS STRENGTHEN THE WESTERLY FLOW ALOFT AND COMBINE WITH DEEP
LAYER MIXING FOR BREEZY TO WINDY CONDITIONS. SATURDAY,
INDEPENDENCE DAY, WILL BE THE WINDIEST DAY WITH THE HIGHEST
PROBABILITIES FOR 40 MPH WIND GUSTS OR HIGHER ALONG THE ROCKY
MOUNTAIN FRONT. THE GREATEST IMPACTS FROM THE WINDS WILL BE FOR
HOLIDAY RELATED ACTIVITIES AND FOR OUTDOOR RECREATION. RECENT
RAINFALL AND SURFACE GREENING SHOULD PRECLUDE FIRE WEATHER
CONCERNS DESPITE THE LOW AFTERNOON HUMIDITIES.
MID-LEVEL HEIGHTS CONTINUE TO RISE AND BRING SUMMER LIKE
TEMPERATURES EARLY NEXT WEEK. THE ONLY CAVEAT WILL BE A
SOUTHWESTERLY FLOW ALOFT DEVELOPING AGAIN IN RESPONSE TO A TROUGH
MOVING ONTO THE PACIFIC NW COAST. SHORTWAVES LOOK TO INTERACT WITH
BUILDING INSTABILITY FOR INCREASED SHOWER AND THUNDERSTORM
ACTIVITY NEXT MONDAY AND TUESDAY. THE ECMWF EXTREME FORECAST INDEX
(EFI) IS ALREADY BEGINNING TO HIGHLIGHT UNUSUALLY HIGH CAPE AND
SHEAR AVAILABILITY FOR STRONG TO SEVERE STORMS FOR THESE DAYS
SHOULD THIS PATTERN COME TO FRUITION.
-RCG/THOR
- FORECAST CONFIDENCE & SCENARIOS:
THUNDERSTORMS TODAY:
SHOWERS AND THUNDERSTORMS ARE ALREADY UNDERWAY ACROSS SOUTHWEST
MONTANA AND ARE EXPECTED TO BECOME MORE NUMEROUS INTO CENTRAL
MONTANA AS THE DAY CONTINUES. IN GENERAL, MOST OF THESE STORMS
WILL PRODUCE DIME-SIZE OR SMALLER HAIL AND MAXIMUM WIND GUSTS OF
45 MPH. THAT BEING SAID, THERE IS A CHANCE A COUPLE COULD BECOME
SEVERE. THE MAIN THREAT ACROSS THE REGION WILL BE STRONG WINDS BUT
SOUTHWEST MONTANA, IN PARTICULAR, WILL CARRY THE HIGHEST CHANCES
FOR LARGER HAIL IF IT OCCURS.
ADDITIONALLY, THESE STORMS ARE EXPECTED TO BE RELATIVELY SLOW-
MOVING WHICH MAY LEAD TO SOME MINOR FLOODING IN TYPICAL FLOOD-
PRONE AREAS. OVERALL, SOUTHWEST MONTANA HAS BEEN DRY OVER THE
PAST COUPLE MONTHS COMPARED TO THE REST OF THE REGION. THIS MEANS
THAT, WHILE SOME ISOLATED PONDING AND FLOODING OF FLOOD-PRONE
AREAS IS POSSIBLE, WIDESPREAD, SIGNIFICANT FLOODING IS GENERALLY
NOT EXPECTED ACROSS A GOOD PORTION OF SOUTHWEST MONTANA. THE
EXCEPTION TO THIS ARE THE AREAS THAT ARE CURRENTLY UNDER A FLASH
FLOOD WATCH. THESE AREAS, INCLUDING NORTHWEST BEAVERHEAD COUNTY,
THE BOULDER HILL REGION, AND THE HORSE GULCH BURN SCAR HAVE
ADDITIONAL COMPOUNDING CONCERNS THAT MAY MAKE ANY HEAVY RAINFALL
FROM THUNDERSTORMS A FLOOD THREAT. A MORE IN-DEPTH DISCUSSION ON
THIS CAN BE FOUND IN THE HYDROLOGY SECTION.
THUNDERSTORMS THURSDAY/FRIDAY:
ADDITIONAL ROUNDS OF THUNDERSTORMS ARE EXPECTED THURSDAY AND
FRIDAY AFTERNOON. RIGHT NOW, CONDITIONS LOOK A BIT MARGINAL FOR
DEVELOPMENT IN OUR PORTION OF MONTANA. COVERAGE IS LIKELY TO BE
ISOLATED TO SCATTERED AT BEST AND THE MAIN CONCERNS WILL BE
LIGHTNING AND GUSTY WINDS IMPACTING THOSE WHO ARE RECREATING
OUTDOORS LEADING UP TO THE HOLIDAY WEEKEND.
WARM, DRY, BREEZY THIS WEEKEND:
IN GENERAL NO MAJOR IMPACTS TO THE PUBLIC ARE EXPECTED OVER THE
HOLIDAY WEEKEND. TEMPERATURES ARE EXPECTED TO WARM INTO THE 80S
THIS WEEKEND ACROSS THE LOWER ELEVATIONS. WHILE THIS PUTS US
CLOSER TO THE SEASONAL AVERAGE, IT WILL BE COMPARATIVELY WARMER
THAN WHAT WE HAVE EXPERIENCED THIS PAST WEEK. COMBINED WITH THE
INFLUX OF FOLKS SPENDING A LOT OF TIME OUTDOORS, THERE ARE SOME
MINOR CONCERNS FOR HEAT-RELATED ILLNESS DURING THE DAY
PARTICULARLY FOR THOSE THAT ARE SENSITIVE TO THE HEAT.
BREEZY AND DRY CONDITIONS ARE EXPECTED THROUGH THE AFTERNOON WHICH
COULD HAVE SOME MINOR IMPACT ON AFTERNOON HOLIDAY PLANS BUT
SIGNIFICANT SYNOPTIC WINDS ARE NOT EXPECTED. THE WINDS WILL BE
PRETTY DIURNALLY DRIVEN SO THEY SHOULD TAPER OFF BY THE TIME THE
BIGGER FIREWORKS DISPLAYS ARE OCCURRING BUT FOLKS IN GENERAL
SHOULD STILL EXERCISE FIREWORK SAFETY, EVEN IN AREAS THAT HAVE
BEEN WETTER OVER THE PAST WEEK.
WARMER AND MORE ACTIVE NEXT WEEK:
WHILE THERE IS STILL A BIT OF UNCERTAINTY AS TO HOW EARLY NEXT
WEEK WILL PLAY OUT, THERE ARE STILL STRONG SIGNALS IN THE LONG-
TERM MODELS THAT WE MAY BE HEADING TOWARDS A WARMER PERIOD WITH
DAILY CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS.
-THOR
AVIATION
02/00Z TAF PERIOD
SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THIS EVENING,
MAINLY ACROSS SOUTHWEST AND CENTRAL MT. THESE STORMS MAY PRODUCE
GUSTY, ERRATIC WINDS AS WELL AS FREQUENT LIGHTNING. VFR CONDITIONS
WILL GENERALLY PREVAIL THROUGHOUT THE TAF PERIOD, WITH MVFR
CONDITIONS AND MOUNTAIN OBSCURATION POSSIBLE AT TIMES DUE TO A
PASSING SHOWER OR THUNDERSTORM. THUNDERSTORMS DISSIPATE AFTER 06Z,
FOLLOWED BY CALM CONDITIONS THROUGHOUT THE REST OF THE TAF
PERIOD. -DZOMBA
HYDROLOGY
MANY GLACIER AREA: FLOODING HAS NOW DECREASED TO MINOR LEVELS
MAINLY IMPACTING CAMPGROUNDS AND SOME TRAILS. GIVEN THAT FLOODING
HAS DECREASED BELOW WARNING LEVELS, THE FLOOD WARNING HAS BEEN
REPLACED WITH A FLOOD ADVISORY THROUGH THURSDAY AFTERNOON.
ADDITIONAL RAINFALL IS NOT EXPECTED OVER THE NEXT 24 HOURS WHICH
SHOULD HELP EASE SOME CONCERNS AND ALLOW THE AREA TO CONTINUE
DRAINING AND RECOVERING.
HORSE GULCH BURN SCAR: SLOW-MOVING THUNDERSTORMS WITH THE
POTENTIAL TO BRING HEAVY RAIN ARE POSSIBLE ALONG THE HORSE GULCH
BURN SCAR. THE PRIMARY CONCERN OUTSIDE OF FLASH FLOODING WILL BE
DEBRIS FLOWS. GIVEN THE PAST BEHAVIOR OF THE BURN SCAR, THE AMOUNT
OF PRECIPITATION RECEIVED IN THE LAST FEW DAYS, AND THE AMOUNT OF
PRECIPITATION POSSIBLE ACCORDING TO HI-RES MODEL GUIDANCE, THE
DECISION WAS MADE TO PUT OUT A FLASH FLOOD WATCH FOR THE BURN SCAR
THROUGH THE EVENING. ONE OF THE MAJOR THINGS TO CONSIDER FOR THOSE
LIVING AND RECREATING IN THE AREA IS EVEN IF YOU DO NOT PERSONALLY
RECEIVE RAIN, IF ANY HIGHER PORTION OF THE BURN SCAR RECEIVES
ENOUGH RAIN TO FLOOD OR START A DEBRIS FLOW, IT CAN QUICKLY MOVE
DOWNHILL AND CAUSE SIGNIFICANT IMPACTS. THEREFORE, BE AWARE OF
YOUR SURROUNDINGS AND HAVE A WAY TO RECEIVE WARNINGS IN CASE THEY
ARE ISSUED.
NORTHWEST BEAVERHEAD COUNTY AND BOULDER MOUNTAINS: SLOW-MOVING
THUNDERSTORMS OVER MOUNTAINOUS TERRAIN THAT HAS PREVIOUSLY
RECEIVED AT LEAST A COUPLE INCHES OF PRECIPITATION COULD CAUSE
FLASH FLOODING. HI-RES MODEL GUIDANCE HAS POINTED OUT THESE
PORTIONS OF SOUTHWEST MONTANA AS HAVING THE HIGHEST PROBABILITY
FOR HIGHER RAINFALL RATES AND AMOUNTS. IN PARTICULAR WITH THE
MOUNTAINS IN NORTHWEST BEAVERHEAD COUNTY, THERE IS A CONCERN FOR
FLOODING WITH RAIN FALLING ON TOP OF SNOW AT THE HIGHER ELEVATIONS
WHICH CAN THEN BECOME INCREASED RUNOFF FURTHER DOWNSTREAM. FOR
NOW THIS SITUATION WILL BE MONITORED CAREFULLY BUT THE WATCH WILL
REMAIN IN EFFECT UNTIL MIDNIGHT TO ADDRESS SOME OF THE MAIN
CONCERNS WITH THE POTENTIAL FOR FLASH FLOODING.
-THOR
PRELIMINARY POINT TEMPS/POPS
GTF 51 77 51 79 / 40 0 0 20
CTB 47 73 48 74 / 0 0 0 0
HLN 50 76 52 78 / 50 20 10 30
BZN 45 76 48 77 / 50 10 10 20
WYS 37 72 39 73 / 20 0 10 10
DLN 44 75 46 76 / 60 0 0 10
HVR 52 80 52 81 / 20 10 0 10
LWT 47 74 48 74 / 60 20 20 60
TFX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR ELKHORN AND BOULDER
MOUNTAINS-NORTHWEST BEAVERHEAD COUNTY.
FLASH FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR BIG BELT,
BRIDGER AND CASTLE MOUNTAINS.
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