261
FXUS65 KTFX 050602
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1202 AM MDT SAT SEP 5 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- IT WILL BE WINDY ACROSS NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA THIS AFTERNOON WITH ISOLATED SHOWERS AND
THUNDERSTORMS.
- WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL AFFECT
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA SUNDAY
THROUGH EARLY NEXT WEEK.
- IT WILL COOL OFF THIS WEEKEND THOUGH EARLY NEXT WEEK.
DISCUSSION
/ISSUED 550 PM MDT FRI SEP 4 2026/
- METEOROLOGICAL OVERVIEW:
THIS AFTERNOON AN UPPER-LEVEL CLOSED LOW IS OVER WASHINGTON AND
OREGON WITH SOUTHERLY FLOW OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL BRING BREEZY WINDS TO THE AREA WITH
THE STRONGEST WINDS IN NORTH-SOUTH ORIENTATED VALLEYS IN
SOUTHWESTERN MONTANA. THERE WILL BE ISOLATED SHOWERS AND
THUNDERSTORMS PRIMARILY CONFINED ALONG THE CONTINENTAL DIVIDE THIS
AFTERNOON/EVENING. SOME OF THESE SHOWERS AND THUNDERSTORMS COULD
MAKE IT AS FAR THE I-15 CORRIDOR BY THIS EVENING. IT WILL BE AROUND
SEASONAL AVERAGES TODAY. ON SATURDAY THE UPPER-LEVEL CLOSED LOW
REMAINS OVER WASHINGTON AND OREGON WITH SOUTHERLY FLOW ALOFT. IT
WILL REMAIN WARM AND BREEZY ON SATURDAY WITH SHOWERS AND
THUNDERSTORMS PRIMARILY CONFINED TO THE CONTINENTAL DIVIDE.
ON SUNDAY THE UPPER-LEVEL CLOSED LOW REMAINS OVER WASHINGTON AND
OREGON WITH SOUTHERLY FLOW ALOFT. AS THE UPPER-LEVEL LOW WEAKENS AND
BEGINS TO SLIDE EAST A SHORTWAVE MOVES THROUGH THE UPPER-LEVEL
TROUGH. THIS WILL BRING SHOWERS AND THUNDERSTORMS TO NORTH-CENTRAL
MONTANA WITH STRONGER THUNDERSTORMS EXPECTED IN BLAINE AND FERGUS
COUNTY. SEE THE FORECAST CONFIDENCE & SCENARIOS SECTION FOR
DETAILS. ON MONDAY THE UPPER-LEVEL TROUGH MOVES OVER NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS WILL BRING COOLER
TEMPERATURES AND WIDESPREAD SHOWERS AND THUNDERSTORMS TO THE AREA
ON MONDAY. ON TUESDAY THE UPPER-LEVEL TROUGH BEGINS TO EXIT
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS WILL ALLOW
TEMPERATURES TO GRADUALLY WARM UP BUT REMAIN BELOW SEASONAL
AVERAGES ACROSS THE AREA. RAIN SHOWERS WILL LINGER THROUGH THE DAY
ON TUESDAY. ON WEDNESDAY AND THURSDAY AN UPPER-LEVEL RIDGE BUILDS
BACK IN OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA.
THIS WILL ALLOW TEMPERATURES TO WARM UP WITH MOSTLY DRY WEATHER.
-IG
- FORECAST CONFIDENCE & SCENARIOS:
ON SUNDAY THERE IS A 30 - 40% CHANCE FOR THUNDERSTORMS ALONG AND
EAST OF A CUT BANK TO GREAT FALLS LINE. FOR SUNDAY THE STORM
PREDICTION CENTER HAS ISSUED A MARGINAL RISK (5% CHANCE FOR 58 MPH
WIND GUSTS OR GREATER AND/OR A 5% CHANCE FOR HAIL 1 INCH IN DIAMETER
OR GREATER) FOR SEVERE THUNDERSTORMS NORTHEAST OF A CUT BANK TO
GREAT FALLS TO JUDITH GAP LINE. ON MONDAY THERE IS A 25 - 40%
CHANCE FOR THUNDERSTORMS ACROSS NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA.
FROM 6 AM SUNDAY THROUGH 6 AM TUESDAY THERE IS GREATER THAN A 60%
CHANCE FOR 2 INCHES OF RAIN OR GREATER ALONG THE HI-LINE. FROM 6 AM
SUNDAY THROUGH 6 AM TUESDAY THERE IS A 60 - 80% CHANCE FOR 1 INCH OF
RAINFALL OR GREATER ACROSS NORTH-CENTRAL MONTANA. FROM 6 AM SUNDAY
THROUGH 6 AM TUESDAY THERE IS A 30 - 60% CHANCE FOR HALF AN INCH OF
RAIN OR GREATER ACROSS CENTRAL AND SOUTHWESTERN MONTANA.
DETERMINISTIC MODELS ARE STILL FLIP-FLOPING WITH RESPECT TO WHERE
THE HEAVIEST PRECIPITATION AMOUNTS WILL BE. -IG
AVIATION
05/06Z TAF PERIOD
SCATTERED RAIN SHOWERS WILL CONTINUE THROUGH THE REST OF THE NIGHT
WITH MINOR IMPACTS POSSIBLE FOR KGTF AND KLWT AND MORE SIGNIFICANT
IMPACTS EXPECTED AROUND KCTB WHERE PERIODS OF MVFR/IFR CONDITIONS
ARE POSSIBLE. FOR AREAS ALONG AND WEST OF THE I-15 CORRIDOR, LOW
STRATUS IS EXPECTED TO LINGER THROUGH THE REST OF THE NIGHT INTO
SATURDAY MORNING BEFORE ANOTHER ROUND OF MOISTURE IS EXPECTED
SATURDAY AFTERNOON. MOUNTAIN OBSCURATION WILL BE AN ONGOING
CONCERN ALONG THE CONTINENTAL DIVIDE THROUGH THE PERIOD.
OTHERWISE THERE ARE SOME CONCERNS THAT FOG COULD DEVELOP AT BOTH
KBZN AND KWYS RIGHT AROUND SUNRISE ON SATURDAY BUT CONFIDENCE IN
THE EXACT IMPACT AND TIMING WAS TOO LOW TO INCLUDE IT IN THE TAF.
FOR KGTF: VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD WITH A
LOW STRATUS DECK EXPECTED TO LINGER THROUGH AT LEAST THE MID-
MORNING HOURS ON SATURDAY. WINDS IN THE EARLY AFTERNOON WILL START
TO PICK UP OUT OF THE EAST/NORTHEAST WITH GUSTS UP TO 20KTS
POSSIBLE. OVERALL THE RISK FOR EXCEEDING THE CROSSWIND THRESHOLD
IS RATHER LOW AT AROUND 15%. THE TIME FRAMES TO WATCH FOR WILL BE
RIGHT AS THE WINDS START TO INCREASE OUT OF THE EAST TOWARDS THE
EARLY AFTERNOON AND THEN AS SHOWERS AND THUNDERSTORMS MOVE THROUGH
WHICH MAY PRODUCE GUSTY/ERRATIC WINDS AT TIMES. THE MAIN
THREAT FOR THUNDERSTORMS AT KGTF WILL BE BETWEEN 06/00Z AND
06/05Z. -THOR
PRELIMINARY POINT TEMPS/POPS
GTF 49 75 50 75 / 40 10 30 10
CTB 46 67 48 64 / 70 70 70 70
HLN 49 77 49 78 / 20 20 30 10
BZN 46 81 46 82 / 0 0 0 0
WYS 39 72 38 75 / 0 0 0 0
DLN 45 79 44 81 / 10 0 0 0
HVR 50 81 55 80 / 0 10 30 60
LWT 48 78 50 78 / 0 0 10 30
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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