040
FXUS65 KTFX 120517
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1117 PM MDT THU SEP 11 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON, SOME OF WHICH COULD PRODUCE SOME GUSTY WINDS OR
LOCALIZED HEAVY RAIN.
- BRIEFLY WARMER SUNDAY.
- COOL AND UNSETTLED WEATHER RETURNS ON MONDAY.
UPDATE
/ISSUED 811 PM MDT THU SEP 11 2025/
SHOWERS AND THUNDERSTORMS CONTINUE TO TRACK GENERALLY NORTHWARD
ACROSS THE AREA WITHIN THE BROAD CIRCULATION OF AN ELONGATED
TROUGH EXTENDING FROM THE GREAT BASIN THROUGH THE NORTHERN
ROCKIES. A MORE CONCENTRATED AREA OF SHOWERS AND THUNDERSTORMS IS
ASSOCIATED WITH AN EMBEDDED VORTICITY FEATURE LIFTING OUT ACROSS
WEST-CENTRAL MT THIS EVENING, BUT OVERALL DIFFLUENT FLOW ALOFT
AND LINGERING MID-LEVEL INSTABILITY WILL MAINTAIN A RISK FOR
SHOWERS AND AT LEAST A FEW ISOLATED THUNDERSTORMS THROUGH MUCH OF
THE OVERNIGHT PERIOD WITH ACTIVITY GRADUALLY SHIFTING NORTHWARD
ACROSS NORTH-CENTRAL MT WHILE DECREASING OR ENDING ACROSS SW MT.
CLEARING OF CLOUDS ACROSS SOUTHWEST MT MAY LEAD TO SOME PATCHY
VALLEY FOG DEVELOPMENT, ESPECIALLY IN LOCATIONS THAT SAW
PRECIPITATION EARLIER THIS EVENING. HOENISCH
DISCUSSION
/ISSUED 811 PM MDT THU SEP 11 2025/
- METEOROLOGICAL OVERVIEW:
A BROAD, SLOW MOVING, AND GRADUALLY WEAKENING UPPER LEVEL TROUGH
CURRENTLY OVER THE WESTERN US WILL KEEP US COOL AND UNSETTLED THE
NEXT FEW DAYS BEFORE ANOTHER TROUGH APPROACHES FROM THE WEST AND
FORCES IT TO MOVE NORTHWARD ON SUNDAY. WITH THIS TROUGH TO THE
WEST, EXPECT SUNDAY TO BE SLIGHTLY WARMER HIGHS GENERALLY 3-5
DEGREES WARMER THAN THE PREVIOUS FEW DAYS. SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO BE AROUND, HOWEVER, ESPECIALLY
LATER IN THE DAY AS AFTERNOON HEATING COMBINES WITH THE
APPROACHING UPPER LEVEL TROUGH. THIS TROUGH WILL SETTLE OVERHEAD
FOR THE FIRST HALF OF THE WEEK, BRINGING COOL AND UNSETTLED TO THE
AREA FOR THE FIRST HALF OF NEXT WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
THE MAIN IMPACTS OVER THE NEXT FEW DAYS WILL BE THE LOW END RISK
FOR AN ISOLATED STRONG AND/OR HEAVY THUNDERSTORM, PARTICULARLY
THIS AFTERNOON AND FRIDAY AFTERNOON. FORECAST SOUNDINGS THE NEXT
TWO DAYS TEND TO SHOW A “TALL, SKINNY” CAPE PROFILE (CAPE BEING A
MEASURE OF INSTABILITY), WHICH INDICATES AN ELEVATED CHANCE FOR
SOME HEAVY RAIN OUT OF ANY SHOWER OR THUNDERSTORM. WPC DOES ALIGN
WITH THIS EXPECTATION, AS WE ARE UNDER A MARGINAL (⅕) RISK FOR
EXCESSIVE RAINFALL. FOR THE MOST PART, THE MAIN CONCERN WILL BE
ANY RECENT BURN SCARS (SUCH AS THE HORSE GULCH OR ANY ACTIVE
FIRES). IN ADDITION TO THE RAIN, A FEW STRONGER WIND GUSTS WILL BE
POSSIBLE FROM SOME OF THE STORMS AS WELL, PARTICULARLY FURTHER
EAST ACROSS THE PLAINS (GENERALLY EAST OF A GREAT FALLS TO HAVRE
LINE).
LOOKING INTO NEXT WEEK, THERE ISN’T MUCH IMPACTFUL WEATHER
EXPECTED AT THIS TIME, THOUGH SHOWERS AND THUNDERSTORMS ARE
EXPECTED MOST DAYS. ALSO OF NOTE, WITH THE UPPER LEVEL LOW ACROSS
THE AREA IN THE FIRST PART OF NEXT WEEK, I CAN’T REALLY RULE OUT
SOME SNOW FALLING AT THE HIGHER ELEVATIONS OF BEAVERHEAD, MADISON,
AND GALLATIN COUNTIES. WHILE ANY SNOW ACCUMULATIONS WILL BE LIGHT
AND ISOLATED TO THE HIGHEST TERRAIN, IT IS STILL NOTEWORTHY AS
SOME OF THE FIRST SNOW OF THE SEASON. LUDWIG
AVIATION
12/06Z TAF PERIOD
VFR CONDITIONS WILL PREDOMINATELY PREVAIL THROUGHOUT THE 1206/1306
TAF PERIOD; HOWEVER, BRIEF PERIODS OF MVFR/LOW-VFR CONDITIONS ARE
POSSIBLE BENEATH SHOWER AND THUNDERSTORM ACTIVITY WITH ADDITIONAL
IMPACTS TO TERMINAL OPERATIONS COMING IN THE FORM OF GUSTY AND
VARIABLE WINDS. WITH SHOWER AND THUNDERSTORM COVERAGE BEING
ISOLATED TO WIDELY SCATTERED OVER MUCH OF THE NEXT 24 HOURS
MENTIONS FOR THIS TAF PERIOD WERE KEPT TO PROB30 GROUPS FOR THE
TIME BEING. WHILE WIDESPREAD MOUNTAIN OBSCURATION IS NOT EXPECTED
THERE WILL BE PERIODS OF OBSCURATION BENEATH/NEAR PRECIPITATION. -
MOLDAN
HYDROLOGY
A FEW HEAVY SHOWERS AND THUNDERSTORMS ARE POSSIBLE TODAY. WHILE
UNLIKELY, SHOULD ONE OF THE HEAVIEST RAIN SHOWERS HIT A BURN SCAR
SOME FLASH FLOODING MAY BE POSSIBLE. LUDWIG
PRELIMINARY POINT TEMPS/POPS
GTF 50 77 49 78 / 40 30 20 20
CTB 48 76 46 77 / 20 30 20 10
HLN 49 77 49 76 / 60 40 20 30
BZN 43 76 44 71 / 40 30 10 30
WYS 33 70 34 63 / 10 30 20 50
DLN 41 72 41 70 / 10 30 10 20
HVR 54 78 51 78 / 40 40 30 20
LWT 48 75 47 71 / 30 40 40 50
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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