498
FXUS65 KTFX 100543
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1143 PM MDT WED SEP 9 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- IT WILL BE DRY AND BREEZY THROUGH THURSDAY.
- PRECIPITATION AND COOLER TEMPERATURES WITH MOUNTAIN SNOW IS
EXPECTED FRIDAY THROUGH THIS WEEKEND.
DISCUSSION
/ISSUED 535 PM MDT WED SEP 9 2026/
- METEOROLOGICAL OVERVIEW:
THIS AFTERNOON THERE IS AN UPPER-LEVEL RIDGE OVER NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. THIS WILL BRING DRY AND WARM
TEMPERATURES (NEAR SEASONAL AVERAGES) TO THE AREA ON WEDNESDAY.
THIS AFTERNOON THE PRESSURE GRADIENT INCREASES WHICH WILL BRING
BREEZY CONDITIONS TO THE ROCKY MOUNTAIN FRONT. ON THURSDAY THE
UPPER-LEVEL RIDGE BEGINS TO BREAK DOWN. THIS WILL KEEP WARMER
TEMPERATURES WITH MOSTLY DRY WEATHER FOR THE AREA ON THURSDAY.
THURSDAY EVENING A COLD FRONT WILL MOVE THROUGH NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA.
ON FRIDAY ZONAL FLOW IS OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS COMBINED WITH THE COLD FRONT THAT MOVED
THROUGH WILL BRING COOLER TEMPERATURES (WELL-BELOW SEASONAL
AVERAGES). ON FRIDAY THERE WILL BE RAIN SHOWERS ACROSS NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. ON SATURDAY AN UPPER-
LEVEL RIDGE BUILDS IN BRIEFLY OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL BRIEFLY BRING DRY CONDITIONS TO
ALL BUT THE ROCKY MOUNTAIN FRONT AND STATUS QUO TEMPERATURES TO
THE AREA. SUNDAY THROUGH MONDAY THERE WILL BE UPPER-LEVEL CLOSED
LOW THAT WILL BRING COOLER TEMPERATURES AND WIDESPREAD
PRECIPITATION TO THE AREA. HIGHER ELEVATIONS LOCATIONS HAVE THE
POTENTIAL TO RECEIVE SNOW FRIDAY THROUGH SUNDAY. SEE THE FORECAST
CONFIDENCE & SCENARIOS SECTION FOR DETAILS. -IG
- FORECAST CONFIDENCE & SCENARIOS:
ON THURSDAY THERE IS GREATER THAN A 60% CHANCE FOR WIND GUSTS OF
45 MPH OR GREATER ACROSS THE ROCKY MOUNTAIN FRONT AND PLAINS WEST
OF 1- 15, THE HI-LINE, AND CASCADE TO JUDITH BASIN COUNTY. ON
THURSDAY ALONG THE ROCKY MOUNTAIN FRONT THERE IS A 60 - 80% CHANCE
FOR WIND GUSTS OF 55 MPH OR GREATER.
SATURDAY THROUGH SUNDAY THERE IS A 40 - 60% CHANCE FOR 4 INCHES OF
SNOW OR GREATER ALONG THE ROCKY MOUNTAIN FRONT. SATURDAY THROUGH
SUNDAY THERE IS A 30 - 60% CHANCE FOR 2 INCHES OF SNOW OR GREATER
ACROSS THE LITTLE BELTS AND MOUNTAINS OF SOUTHWESTERN MONTANA.
SUNDAY MORNING THERE IS A 20 - 40% CHANCE FOR LOW TEMPERATURES OF
36 DEGREES OR LESS ACROSS THE PLAINS OF NORTH-CENTRAL MONTANA. ON
MONDAY THERE IS A 60 - 80% CHANCE FOR LOW TEMPERATURES OF 36
DEGREES OR LOWER ACROSS THE LOWER-ELEVATIONS OF NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. ON MONDAY THERE IS A 30 - 50%
CHANCE FOR LOW TEMPERATURES OF 34 DEGREES OR LOWER ACROSS THE
LOWER-ELEVATIONS OF NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA.
ON FRIDAY THERE IS A 50 - 70% CHANCE FOR A QUARTER INCH OF
PRECIPITATION ACROSS THE MAJORITY OF NORTH-CENTRAL MONTANA. ON
SATURDAY THERE IS A 50% CHANCE FOR A QUARTER INCH OF
PRECIPITATION OR GREATER ALONG THE ROCKY MOUNTAIN FRONT. ON SUNDAY
ACROSS CENTRAL AND NORTH-CENTRAL MONTANA THERE IS A 50 - 70%
CHANCE FOR HALF AN INCH OF RAIN OR GREATER. ON SUNDAY THERE IS 30
- 60% CHANCE FOR A QUARTER INCH OF RAIN OR GREATER ACROSS
SOUTHWESTERN MONTANA. -IG
AVIATION
10/06Z TAF PERIOD
HIGH CONFIDENCE IN VFR CONDITION ACROSS ALL TERMINAL THROUGH THE
TAF PERIOD. I ADDED LLWS TO THE PREVAILING GROUPS FOR TERMINALS
KCTB AND KHVR AS MODEL SOUNDINGS AND SURFACE OBSERVATIONS CONTINUE
TO SUGGEST BOUNDARY LAYER DECOUPLING IS ONGOING LEADING TO STARK
DIFFERENCES BETWEEN SURFACE AND 2KFT WINDS. BREEZY CONDITIONS
WILL BE THE THEME THROUGH MUCH OF THE DAY ESPECIALLY ACROSS NORTH
CENTRAL MONTANA. WIDESPREAD WIND GUSTS OF 20-35KT ARE EXPECTED
AREA WIDE, WITH TERMINALS KCTB, KGTF, AND KHVR LIKELY SEEING GUSTS
ON THE UPPER END OF THAT RANGE. WINDS WILL REMAIN THROUGH THE
PERIOD, ONLY LIGHTENING UP TOWARDS THE IMMEDIATE END. -JR
FOR KGTF: ODDS OF LLWS HAS DROPPED FROM THE PREVIOUS DISCUSSION AS
MIXING HAS PROVED EFFICIENT AT KEEPING SURFACE WINDS UP. WINDS
WILL AGAIN RAMP UP INTO THE AFTERNOON WITH A SLIGHTLY MORE
FAVORABLE SOUTHWEST DIRECTION (220-230 DEGREES) THROUGH 10/18Z
WHEN PROBABILITY OF CROSSWIND CRITERIA EXCEEDANCE IS LOW (30%).
FOLLOWING THAT, WINDS WILL BECOME MORE WESTERLY (250-270 DEGREES)
AND CONFIDENCE IN BOTH CRITICAL SUSTAINED AND GUST CROSSWINDS
RISES GREATLY TO >60%. AS WE NEAR THE END OF THE TAF PERIOD WINDS
WILL BECOME WEAKER WHILE MAINTAINING THE WESTERLY COMPONENT THUS
THE RISK OF 15KT CROSS WINDS DECREASES BUT STILL REMAINS HIGH
ESPECIALLY WITH ANY SPORADIC GUSTS.-JR
PRELIMINARY POINT TEMPS/POPS
GTF 76 55 80 48 / 0 0 10 80
CTB 69 51 72 42 / 0 0 0 60
HLN 75 49 84 50 / 0 0 0 60
BZN 76 45 84 48 / 0 0 0 0
WYS 69 33 72 37 / 0 0 0 0
DLN 77 43 82 46 / 0 0 0 0
HVR 75 50 81 44 / 0 0 0 50
LWT 72 50 83 47 / 0 0 0 70
TFX WATCHES/WARNINGS/ADVISORIES
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