375
FXUS65 KTFX 091806
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1206 PM MDT TUE SEP 9 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- THERE WILL BE ISOLATED SHOWERS AND THUNDERSTORMS TODAY THROUGH
THURSDAY WITH THE COVERAGE INCREASING EACH DAY.
- THERE WILL BE HAZE AROUND NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA THROUGH WEDNESDAY DUE TO WILDFIRES IN THE
REGION.
- FRIDAY THROUGH EARLY NEXT WEEK THERE WILL BE SHOWERS AND
THUNDERSTORMS BUT THERE IS GREAT UNCERTAINTY IN THE TOTAL
RAINFALL AMOUNT.
UPDATE
/ISSUED 829 AM MDT TUE SEP 9 2025/
THERE WERE SOME SLIGHT ADJUSTMENTS MADE TO THE SMOKE FORECAST
BASED ON UPDATED MODEL GUIDANCE BUT OTHERWISE THE GOING FORECAST
REMAINS ON TRACK. -THOR
DISCUSSION
/ISSUED 829 AM MDT TUE SEP 9 2025/
- METEOROLOGICAL OVERVIEW:
TODAY AN UPPER-LEVEL RIDGE IS OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA WITH AN UPPER-LEVEL TROUGH APPROACHING THE
AREA. AS A RESULT IT WILL BE ANOTHER WARM DAY TODAY. DUE TO THE
SOUTHWEST FLOW ALOFT COMBINED WITH MONSOONAL MOISTURE, THERE WILL BE
ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THE STRONGEST
THUNDERSTORMS WILL PRODUCE STRONG WIND GUSTS, FREQUENT LIGHTNING,
AND A BRIEF HEAVY DOWNPOUR. ON WEDNESDAY THE UPPER-LEVEL RIDGE
BEGINS TO SHIFT EASTWARD AND THE UPPER-LEVEL TROUGH APPROACHES
MONTANA. ON WEDNESDAY IT WILL BE ANOTHER WARM DAY WITH ISOLATED
SHOWERS AND THUNDERSTORMS ACROSS NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA DUE TO THE UPPER-LEVEL RIDGE AND APPROACHING
TROUGH COMBINED WITH MONSOONAL MOISTURE. TODAY AND WEDNESDAY DUE TO
THE SOUTHWEST FLOW ALOFT THERE WILL BE HAZY SKIES FROM REGIONAL
WILDFIRES ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA.
ON THURSDAY THE UPPER-LEVEL TROUGH MOVES OVER NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. THIS WILL COOL TEMPERATURES DOWN
AND BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO THE AREA.
THE STRONGEST THUNDERSTORMS WILL PRODUCE STRONG WINDS, FREQUENT
LIGHTNING, AND A BRIEF HEAVY DOWNPOUR. ON FRIDAY THE UPPER-LEVEL
TROUGH REMAINS OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA. THIS WILL COOL TEMPERATURES DOWN TO NEAR SEASONAL AVERAGES
ACROSS THE AREA AND BRING SHOWERS TO THE AREA. SATURDAY THROUGH
MONDAY GENERALLY AN UPPER-LEVEL TROUGH PERSISTS WITH A FEW UPPER-
LEVEL SHORTWAVES. THIS WILL KEEP TEMPERATURES AT ABOUT SEASONAL
AVERAGES WITH DAILY CHANCES FOR SHOWERS ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA SATURDAY THROUGH MONDAY.
- FORECAST CONFIDENCE & SCENARIOS:
TODAY THERE IS A 15 - 30% CHANCE FOR THUNDERSTORMS ACROSS NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. ON WEDNESDAY THERE IS A
10 - 30% CHANCE FOR THUNDERSTORMS WITH THE HIGHEST CHANCES ALONG THE
ROCKY MOUNTAIN FRONT. ON THURSDAY THERE IS A 20 - 40% CHANCE FOR
THUNDERSTORMS ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA WITH THE HIGHEST CHANCES IN NORTH-CENTRAL MONTANA. ON FRIDAY
THERE IS A 20 - 40% CHANCE FOR THUNDERSTORMS ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA.
ON WEDNESDAY THERE IS A 20 - 50% CHANCE FOR A TENTH OF AN INCH OF
RAIN OR GREATER ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA. ON THURSDAY ACROSS NORTH-CENTRAL AND CENTRAL MONTANA THERE
IS A 35 - 60% CHANCE FOR A QUARTER INCH OF RAIN OR GREATER.
FRIDAY THROUGH MONDAY THERE IS HIGH UNCERTAINTY IN THE UPPER-
LEVEL PATTERN. HOWEVER, ALL FOUR CLUSTERS HAVE AN UPPER-LEVEL
TROUGH AFFECTING MONTANA. THIS UPPER-LEVEL TROUGH VARIES
SIGNIFICANTLY IN AMPLITUDE AND POSITION BETWEEN ALL FOUR CLUSTERS
FRIDAY THROUGH MONDAY. THIS INCREASES THE CONFIDENCE THAT
TEMPERATURES WILL BE COOL FRIDAY THROUGH MONDAY. DUE TO THE
VARIOUS TROUGHS THAT THE CLUSTERS SHOW, THE SPREAD BETWEEN THE
10TH PERCENTILE (REASONABLE LOW-END SCENARIO) AND THE 90TH
PERCENTILE (REASONABLE HIGH-END SCENARIO) RAINFALL FROM 6 AM
FRIDAY THROUGH 6 AM MONDAY IS GREATER THAN AN INCH ACROSS NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. -IG
AVIATION
09/18Z TAF PERIOD
VFR IS FORECAST TO DOMINATE TERMINALS ACROSS THE REGION THROUGH
THE NEXT 24+ HOURS WITH A LOW PROBABILITY OF RESTRICTIONS DUE TO
LOCALIZED SHOWER ACTIVITY AND HAZE/SMOKE FROM NEARBY WILDFIRES. AT
THE REGIONAL SCALE, A BAND OF SHOWER ACTIVITY WITH ISOLATED
EMBEDDED T IS PRESENTLY AS OF NOON TUE MOVING INTO SW MT AND IS
EXPECTED TO PUSH NORTH THROUGH TODAY, EXITING NORTH OVERNIGHT.
SHRA/T COVERAGE IS FORECAST TO GROW MORE SPARSE FURTHER NORTH AND
EAST... WITH A 40% CHANCE IN SW MT VERSUS A 20% OR LESS CHANCE
ALONG THE HI-LINE. SCATTERED SHOWERS MAY LINGER ALONG THE HI-LINE
IN THE EARLY DAYTIME ON WED.
THOUGH VFR CIGS ARE EXPECTED WITH THIS ACTIVITY, MOUNTAIN TOP
OBSCURATION WILL STILL BE PRESENT IN THE VICINITY OF SHOWERS.
ADDITIONALLY NEARBY WILDFIRE SMOKE WILL CAUSE PERIODIC REDUCTION
IN VIS...THOUGH RESTRICTIONS ARE NOT EXPECTED AT TERMINALS.
FOR WINDS...BROAD, REGIONAL FLOW IS GENERALLY LIGHT AND OUT OF
THE SOUTHEAST, HOWEVER TERRAIN FUNNELING AND VARIABLE FLOW FROM
SHOWER ACTIVITY WILL DICTATE DIRECTION WITH SPEEDS GENERALLY BELOW
10 KTS. LOCALIZED GUSTS 15-25 KTS CAN BE EXPECTED WITH -SHRA; ISO
T WILL ALSO BE PRESENT IN THE REGION AND CAPABLE OF PRODUCING
GUSTY/ERRATIC WINDS, WITH AROUND A 25% CHANCE IN SW MT.
-CASEY
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 85 53 82 54 / 30 50 10 40
CTB 81 49 79 51 / 30 40 30 50
HLN 82 52 84 54 / 40 50 20 50
BZN 81 47 83 49 / 40 40 20 30
WYS 71 37 73 38 / 50 40 30 40
DLN 74 45 78 44 / 30 40 20 20
HVR 85 55 84 55 / 10 40 40 30
LWT 82 52 82 54 / 10 30 20 40
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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