644
FXUS65 KTFX 230601
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1201 AM MDT FRI OCT 23 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- SIGNIFICANT SHIFT TO COOLER AND WETTER CONDITIONS WILL OCCUR ON
FRIDAY.
- RAIN DEVELOPS TONIGHT WEST OF I-15 WITH RAIN AND MOUNTIAN SNOW EARLY
FRIDAY AND A TRANSITION TO LOWER ELEVATION SNOW BY FRIDAY
EVENING BEFORE PRECIPITATION ENDS.
- GUSTY TO LOCALLY STRONG NORTHWEST WINDS DEVELOP ACROSS NORTH-CENTRAL
MONTANA ON FRIDAY WITH MUCH COOLER TEMPERATURES SPREADING
ACROSS THE AREA BY FRIDAY AFTERNOON.
- DRIER BUT CONTINUED COOLER THAN AVERAGE CONDITIONS ARE
EXPECTED FOR THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
/ISSUED 527 PM MDT THU OCT 22 2026/
- METEOROLOGICAL OVERVIEW:
A SIGNIFICANT SHIFT FROM THE ONGOING MILD/BENIGN WEATHER IS ON TRACK
FOR FRIDAY AS AN UPPER LEVEL TROUGH MOVING ONSHORE INTO CA/NV TODAY
LIFTS NORTH ACROSS MT AHEAD OF AN EASTWARD MOVING TROUGH FROM
NORTHERN PACIFIC.
THE TROUGH LIFTING OUT OF CA/NV WILL SPREAD UNUSUALLY DEEP MOISTURE
FOR THIS TIME OF YEAR (PWATS>200% OF NORMAL) NORTH INTO THE AREA
TONIGHT THROUGH FRIDAY MORNING WITH PRECIPITATION DEVELOPING ACROSS
WESTERN PORTIONS OF THE FORECAST AREA (MAINLY W OF I-15) TONIGHT AS
THIS MOISTURE IS DRAWN NORTH ALONG A DEFORMATION AXIS ACROSS THE
NORTHERN ROCKIES. THIS PRECIPITATION WILL BE A MIX OF DECAYING
CONVECTION THAT DEVELOPS OVER THE GREAT BASIN THIS AFTERNOON WITH
ADDITIONAL LIFT PROVIDED BY UPPER JET ENERGY LIFTING NORTH FROM THE
GREAT BASIN AS WELL AS IN ADVANCE OF THE TROUGH ARRIVING FROM THE
NW.
THE UPPER TROUGH APPROACHING FROM THE NW CROSSES THE NORTHERN
ROCKIES FRIDAY AFTERNOON, SHIFTING THE AXIS OF PRECIPITATION EAST
ACROSS THE AREA WHILE ALSO BRINGING COOLER AIR ALOFT AND LOWERING
SNOW LEVELS BEFORE PRECIPITATION DECREASES FROM WEST TO EAST FRIDAY
EVENING. COOLING ALOFT WILL SUPPORT AN INITIAL DROP IN SNOW LEVELS
FROM ABOVE 9000 FT TO AROUND 6000-7000 FT ACROSS MOST OF THE AREA BY
FRIDAY AFTERNOON, RESULTING IN A CHANGE TO WET SNOW OVER THE
MOUNTAINS. A SECONDARY PUSH OF LOWER LEVEL COOLING SURGES SOUTHEAST
OUT OF AB AS THE NORTHERN UPPER TROUGH AXIS EMERGES EAST OF THE
ROCKIES AND WITH SURFACE LOW PRESSURE DEEPENING ACROSS EASTERN MT.
SNOW LEVELS QUICKLY LOWER TO 3000-4000 FT ACROSS N-CENTRAL MT AS
EARLY AS LATE FRIDAY MORNING ACROSS GLACIER COUNTY AND BY LATE
FRIDAY AFTERNOON ACROSS EASTERN PORTIONS OF NORTH-CENTRAL/CENTRAL MT
AND FRIDAY EVENING ACROSS SW MT VALLEYS. GUSTY TO LOCALLY STRONG
NORTHWEST WINDS DEVELOP WITH THE SURGE OF COOLER AIR ACROSS N-
CENTRAL MT FRIDAY, DRIVEN MOSTLY BY THE SURFACE PRESSURE GRADIENT
BEHIND THE INTENSIFYING LOW TO THE EAST.
MAINLY DRY CONDITIONS FOLLOW FOR THE WEEKEND INTO AT LEAST EARLY
NEXT WEEK WITH TEMPERATURES REMAINING SOMEWHAT COOLER THAN AVERAGE
FOR LATE OCTOBER WITH AFTERNOON TEMPS IN THE MID-UPPER 40S AND
OVERNIGHT LOWS IN THE 20S. A MORE UNSETTLED PERIOD MAY DEVELOP BY
MID TO LATE NEXT WEEK AS THE NEXT TROUGH DIGGING SOUTHWARD ALONG THE
WEST COAST BEGINS TO SHIFT INLAND, THOUGH THERE THERE IS STILL
CONSIDERABLE UNCERTAINTY WITH TIMING AND DETAILS AT THIS POINT.
HOENISCH
- FORECAST CONFIDENCE & SCENARIOS:
PRECIPITATION IMPACTS TONIGHT THROUGH FRIDAY MORNING:
INSTANCES OF LOCALLY MODERATE/HEAVY PRECIPITATION RATES ARE LIKELY
TONIGHT THROUGH FRIDAY MORNING WITH SOME EMBEDDED CONVECTIVE
ELEMENTS AND EVEN SOME ISOLATED THUNDER POSSIBLE.
PRECIPITATION TYPE AND WINTER WEATHER IMPACTS:
THERE IS STILL SOME UNCERTAINTY IN THE HOW QUICKLY THE LOWER LEVEL
COOLING CAN CHANGE PRECIPITATION TO SNOW ACROSS LOWER ELEVATIONS OF
NORTH-CENTRAL MT FRIDAY AFTERNOON. FOR MOST AREAS OUTSIDE OF THE
MOUNTAINS, THE TRANSITION TO WET SNOW WILL OCCUR WITH STILL WARM
GROUND TEMPS AND LITTLE OPPORTUNITY FOR ACCUMULATION BEFORE
PRECIPITATION ENDS FRIDAY EVENING. ACROSS JUDITH BASIN AND FERGUS
COUNTIES HOWEVER THERE IS SOME CONCERN FOR THE TRANSITION TO SNOW
COINCIDING WITH GUSTY NORTHWEST WINDS AND POTENTIAL FOR UPSLOPE
ENHANCEMENT, PARTICULARLY FOR NEAR JUDITH GAP, LEWISTOWN AND AREAS
FROM RAYNESFORD TO GEYSER. WITH POTENTIAL FOR A QUICK 1-2 INCHES OF
SNOWFALL OCCURRING NEAR/SHORTLY AFTER SUNSET FRIDAY AND POTENTIAL
FOR GUSTY WINDS TO ADD TO VISIBILITY REDUCTION, WINTER WEATHER
ADVISORIES WERE ADDED FOR THESE AREAS.
WIND IMPACTS:
STRONGEST NORTHWEST WINDS ON FRIDAY ARE EXPECTED NEAR THE CANADIAN
BORDER AND AREAS WHERE WINDS ARE ENHANCED NEAR THE ISLAND MTN
RANGES, PARTICULARLY THE SWEET GRASS HILLS, BEARS PAW, JUDITH AND
SNOWY RANGES, WHERE PROBABILITIES FOR GUSTS IN EXCESS OF 55 MPH
ARE 60-80% AND A HIGH WIND WARNING HAS BEEN ISSUED. GUSTS IN
EXCESS OF 40 MPH ARE LIKELY ACROSS MOST OF NORTH-CENRTAL MT FRIDAY
AFTERNOON, WHICH WHEN COMBINED WITH TEMPERATURES FALLING TO THE
30S WILL ADD TO THE RAW CONDITIONS FOR THOSE OUTDOORS. HOENISCH
AVIATION
23/06Z TAF PERIOD
INITIAL CONCERN THIS TAF PERIOD WILL BE FOR RAIN DEVELOPING
TONIGHT FROM SOUTH TO NORTH ACROSS THE REGION. CEILINGS SLOWLY
LOWER AS THE RAIN DEVELOPS, EVENTUALLY RESULTING IN MOUNTAIN
OBSCURATION BY 23/15Z. A COLD FRONT THEN MOVES SOUTHWARD OVER THE
PLAINS FRIDAY MORNING AND INTO CENTRAL AND SOUTHWEST MONTANA
VALLEYS EARLY IN THE AFTERNOON. A SHARP WIND SHIFT WITH GUSTY
WINDS WILL ACCOMPANY THE FRONT, ALONG WITH EVEN LOWER CEILINGS.
RAIN TRANSITIONS TO SNOW IN MANY AREAS BEHIND THE COLD FRONT,
THOUGH CONFIDENCE IN HOW QUICK THIS TRANSITION OCCURS IS LOWER
CONFIDENCE ACROSS SW MT.
GUSTY WINDS WILL BE STRONG AT TIMES OVER THE PLAINS THROUGH THE
AFTERNOON FRIDAY WITH SOME VISIBILITY REDUCTIONS DUE TO BLSN
POSSIBLE AT KLWT. MVFR TO IFR CONDITIONS ARE EXPECTED AFTER 23/15Z
WITH PERIODS OF LIFR MOST LIKELY TO OCCUR THROUGH THE AFTERNOON
AND EVENING HOURS AT KLWT AND KGTF. PRECIPITATION WILL START TO
TAPER OFF AFTER 24/03Z. -AM/THOR
PRELIMINARY POINT TEMPS/POPS
GTF 42 52 27 45 / 0 100 50 0
CTB 36 48 22 44 / 10 90 0 0
HLN 43 53 23 46 / 30 100 60 0
BZN 40 55 22 43 / 10 100 100 0
WYS 32 45 17 46 / 50 100 90 0
DLN 42 49 26 45 / 80 100 90 0
HVR 42 57 25 46 / 0 100 80 0
LWT 45 62 23 42 / 0 100 100 0
TFX WATCHES/WARNINGS/ADVISORIES
HIGH WIND WARNING FROM 11 AM TO 3 PM MDT FRIDAY FOR EASTERN
GLACIER, WESTERN TOOLE, AND CENTRAL PONDERA-EASTERN TOOLE AND
LIBERTY-HILL COUNTY.
WINTER WEATHER ADVISORY FROM 4 PM FRIDAY TO 3 AM MDT SATURDAY
FOR BEARS PAW MOUNTAINS AND SOUTHERN BLAINE-FERGUS COUNTY BELOW
4500FT-JUDITH BASIN COUNTY AND JUDITH GAP-SNOWY AND JUDITH
MOUNTAINS.
HIGH WIND WARNING FROM NOON TO 9 PM MDT FRIDAY FOR FERGUS COUNTY
BELOW 4500FT.
WINTER WEATHER ADVISORY FROM NOON FRIDAY TO MIDNIGHT MDT FRIDAY
NIGHT FOR ELKHORN AND BOULDER MOUNTAINS-GALLATIN AND MADISON
COUNTY MOUNTAINS AND CENTENNIAL MOUNTAINS-LITTLE BELT AND
HIGHWOOD MOUNTAINS-NORTHWEST BEAVERHEAD COUNTY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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