232
FXUS65 KTFX 291125
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
525 AM MDT FRI MAY 29 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- EARLY MORNING SHOWERS OVER NORTH CENTRAL MT WILL GIVE WAY TO
MORE WIDESPREAD THUNDERSTORMS THIS AFTERNOON, SOME OF WHICH
COULD BE SEVERE.
- WIDESPREAD RAIN AND HIGH MOUNTAIN SNOW EXPECTED SATURDAY THROUGH
MONDAY, ALONG WITH COOLER TEMPERATURES.
- TEMPERATURES SLOWLY WARM LATE NEXT WEEK, WITH SCATTERED SHOWERS
AND THUNDERSTORMS CONTINUING.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
A SLOW MOVING UPPER LEVEL LOW WILL AFFECT OUR CWA OVER THE NEXT
SEVERAL DAYS. THERE WILL BE A FEW MORNING SHOWERS OVER NORTH
CENTRAL MT, OTHERWISE EXPECT ANOTHER WARM AFTERNOON IN THE
SOUTHWEST AND A HOT AFTERNOON OVER NORTH CENTRAL MT.
SHOWERS/THUNDERSTORMS REDEVELOP THIS AFTERNOON OVER THE SOUTHWEST
AND PUSH NORTHWARD INTO NORTH CENTRAL MT BY EVENING. A FEW STORMS
COULD BE SEVERE OVER NORTH CENTRAL MT, WITH DAMAGING WIND GUST THE
MAIN IMPACT, ALONG WITH SOME HEAVY RAINFALL.
FOR SATURDAY THROUGH MONDAY, THE UPPER LEVEL LOW WILL CONTINUE TO
DRIFT NORTHWARD AND MOVE FROM SOUTH TO NORTH ACROSS MT. THIS WILL
ALLOW FOR WIDESPREAD RAIN TO AFFECT MUCH OF THE CWA THIS WEEKEND,
WITH THE HEAVIEST RAINFALL LIKELY OVER THE WESTERN HALF OF NORTH
CENTRAL MT. TEMPERATURES WILL BE MUCH COOLER STARTING SATURDAY.
THE AIRMASS WILL STILL BE UNSTABLE ENOUGH FOR SOME LIGHTNING
STRIKES DURING THE AFTERNOON/EVENING HOURS OVER THE WEEKEND
THOUGH. SNOW LEVELS WILL LOWER, BUT I AM THINKING NOT QUITE AS LOW
AS PREVIOUSLY FORECASTED FOR MOST AREAS. OVERALL, MOST OF THE
ACCUMULATING SNOWFALL WILL REMAIN ABOVE 7000 FEET OR SO.
FOR TUESDAY THROUGH NEXT FRIDAY...EXPECT A GRADUAL WARMING TREND
BY LATER NEXT WEEK. THERE WILL CONTINUE TO BE A CHANCE FOR
SCATTERED SHOWERS/THUNDERSTORMS MOST DAYS NEXT WEEK. THE LATEST
GFS/EC ARE SHOWING SIGNS OF ANOTHER FAIRLY GOOD WEATHER SYSTEM
LATER NEXT WEEK, BUT THE MODELS DIFFER ON TIMING/STRENGTH A
BIT, THUS CONFIDENCE IS LOW AT THIS TIME FOR PRECIP AMOUNTS LATE
NEXT WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
WITH A SOUTHWEST FLOW ALOFT THIS AFTERNOON, THERE IS A GOOD CHANCE
FOR ANOTHER ROUND OF SHOWERS/THUNDERSTORMS OVER NORTH CENTRAL MT.
THE BEST TIME FRAME FOR ANY SEVERE STORMS WILL BE FROM ABOUT 4 PM
UNTIL 8 PM, ALONG THE HIGHWAY 2 CORRIDOR FROM CUT BANK TO HAVRE.
OVER THE WEEKEND, THE PROBABILITY OF 2 INCHES OF RAINFALL IS ABOUT
60 PERCENT WEST OF A LINE FROM GREAT FALLS TO HAVRE. THE
PROBABILITY FOR 3 INCHES OF RAIN IS GENERALLY LESS THAN 10
PERCENT. THUS A FEW LOCATIONS WILL RECEIVE CLOSE TO 3 INCHES OF
RAIN, BUT OVERALL THERE IS A 90 PERCENT CHANCE MOST AREAS WILL SEE
LESS THAN 3 INCHES OF RAIN.
THE PROBABILITY FOR 2 INCHES OF SNOW IS ONLY 50 PERCENT, AND THAT
IS FOR ELEVATIONS ABOVE 7000 FEET. BRUSDA
AVIATION
29/12Z TAF PERIOD
ISOLATED THUNDERSTORMS WILL AFFECT AREAS MAINLY NORTH OF HIGHWAY 2
THROUGH ABOUT 14Z THIS MORNING. OTHERWISE SCATTERED THUNDERSTORMS
WILL DEVELOP OVER SOUTHWEST MT THIS AFTERNOON AND THEN MOVE
NORTHWARD THROUGH NORTH CENTRAL MT DURING THE LATE
AFTERNOON/EVENING HOURS. STRONG GUSTY SURFACE WINDS/HEAVY RAIN
LIKELY WITH STRONGER STORMS THIS AFTERNOON. A MORE WIDESPREAD RAIN
STARTS TO DEVELOP AFTER 09Z SATURDAY OVER SOUTHWEST MT, MOVING
NORTHWEST TOWARDS THE HELENA/GREAT FALLS AREA BY 12Z SAT.
WIDESPREAD RAIN LIKELY THE REST OF SAT AND MUCH OF SUN OVER THE
CWA. MOUNTAINS WILL BE OBSCURED AT TIMES THIS AFTERNOON BY PASSING
THUNDERSTORMS, THEN BECOME OBSCURED ONCE AGAIN OVER
CENTRAL/SOUTHWEST MT AFTER 09Z SAT AS THE WIDESPREAD RAIN BEGINS.
BRUSDA
HYDROLOGY
WIDESPREAD RAINFALL WILL AFFECT THE CWA THIS WEEKEND. IN LOOKING
AT NOAA ATLAS 14, 2 INCH RAINFALLS IN A 2 DAY PERIOD HAPPEN ABOUT
EVERY 2 TO 5 YEARS IN THE GREAT FALLS AREA. FOR AREAS WEST OF
AUGUSTA, A 3 INCH RAINFALL IN A 2 DAY PERIOD ALSO HAPPENS ABOUT
EVERY 2 TO 5 YEARS. THUS THE SPRING STORM THAT WE ARE FORECASTING
THIS WEEKEND IS ON PAR FOR A FAIRLY COMMON SPRING STORM...IT IS
JUST THAT WE HAVE NOT HAD A STORM LIKE THIS IN A FEW YEARS.
IN TERMS OF FLOOD STATEMENTS, AN ESF WILL BE ISSUED THIS MORNING
TO TALK ABOUT SOME OF THE EXPECTED RAINFALL OVER NORTH CENTRAL
MT. SOME OF THE BIGGER RIVERS ARE FORECAST TO RISE NEAR OR GO INTO
ACTION STAGE THIS WEEKEND/EARLY NEXT WEEK, HOWEVER, NO RIVER IS
CURRENTLY FORECAST TO GO INTO FLOOD STAGE. THAT COULD CHANGE AS
NEWER INFORMATION COMES IN. MANY MOUNTAINS HAVE MELTED OUT THE
SNOWPACK FOR THE SEASON, BUT A FEW AREAS ALONG THE DIVIDE DO HAVE
SNOW, ESPECIALLY GLACIER PARK. THIS WILL ADD TO RUN OFF CONCERNS
FOR RIVERS LIKE THE SUN RIVER, BADGER CREEK, AND THE ST MARY'S
RIVER. THUS THERE IS THE POTENTIAL THAT SOME RIVER FLOOD
STATEMENTS MIGHT BE NEEDED.
ADDITIONALLY, AREAL QPF OF 1 TO 3 INCHES IS POSSIBLE OVER THE
WESTERN HALF OF NORTH CENTRAL MT. OVERALL, MUCH OF THE AREA SHOULD
BE ABLE TO HANDLE THE FIRST FEW INCHES. THOSE 10 PERCENT LOCATIONS
THAT RECEIVE NEAR 3 INCHES OF RAINFALL COULD HAVE SOME IMPACTS,
AND THUS SOME AREAL FLOOD STATEMENTS MIGHT BE NEEDED. BRUSDA
PRELIMINARY POINT TEMPS/POPS
GTF 88 55 66 47 / 30 60 90 90
CTB 84 52 64 42 / 40 40 80 90
HLN 86 53 62 46 / 30 50 90 90
BZN 85 47 60 41 / 20 40 100 100
WYS 78 39 52 35 / 10 30 90 90
DLN 80 47 58 40 / 10 40 100 90
HVR 92 54 79 48 / 30 40 60 90
LWT 86 49 67 44 / 30 40 90 90
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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