833
FXUS65 KTFX 310604
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1204 AM MDT MON AUG 31 2026
KEY MESSAGES
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES THROUGH THE WORK
WEEK, WITH THE WARMEST DAY OCCURRING ON TUESDAY.
- GUSTY WINDS ON WEDNESDAY AND THURSDAY, ESPECIALLY ALONG THE
ROCKY MOUNTAIN FRONT AND IN THE NORTH-SOUTH ORIENTATED VALLEYS
OF SOUTHWEST MONTANA.
- SHOWER AND THUNDERSTORM CHANCES RETURN ON TUESDAY AND
WEDNESDAY.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
AS THE UPPER LEVEL TROUGH MOVES NORTHEAST OUT OF THE STATE, UPPER
LEVEL RIDGING BEGINS TO BUILD TO THE WEST. THIS BUILDING RIDGE OF
HIGH PRESSURE WILL ALLOW FOR TEMPERATURES TO WARM BACK UP, WITH
HIGHS TODAY IN THE MID 70S TO MID 80S. ON TUESDAY, THE RIDGE WILL
BEGIN TO PROPAGATE EASTWARD WITH A NEGATIVE TILT, CREATING
SOUTHWESTERLY FLOW ALOFT. EMBEDDED SHORTWAVES WITHIN THIS FLOW WILL
CREATE ENOUGH INSTABILITY FOR THE DEVELOPMENT OF AFTERNOON/EVENING
THUNDERSTORMS, MAINLY IN SOUTHWEST MT. INCREASED MOISTURE ALOFT WILL
RESULT IN CHANCES FOR SOME SHOWERS IN THE AFTERNOON/EVENING HOURS IN
SOUTHWEST MT AS WELL.
ON WEDNESDAY, THE UPPER LEVEL RIDGE EXITS THE REGION, AND AN UPPER
LEVEL TROUGH SWING NORTHEASTWARD FROM NORTHERN CALIFORNIA INTO THE
NORTHERN ROCKIES. THIS WILL ALLOW FOR SHOWER AND THUNDERSTORM
CHANCES TO BECOME MORE WIDESPREAD, AS WELL AS STRONG SOUTHWESTERLY
WINDS TO FORM. ON THURSDAY, THIS SMALLER UPPER LEVEL TROUGH WILL
GIVE WAY TO A MUCH LARGER UPPER LEVEL TROUGH FORMING OVER THE
OLYMPIC PENINSULA, ALLOWING ONCE AGAIN FOR WIDESPREAD SHOWER AND
THUNDERSTORM CHANCES AND STRONG SOUTHWESTERLY WINDS.
LOOKING INTO FRIDAY AND BEYOND, CONDITIONS WILL DEPEND OF WHAT THIS
LARGER UPPER LEVEL TROUGH DOES. THERE REMAINS INCONSISTENCY IN WHAT
THE MODELS ARE PREDICTING FOR THE PATH OF THIS TROUGH, AS OUTLINED
IN THE FORECAST CONFIDENCE AND SCENARIOS SECTION BELOW. -DZOMBA
FORECAST CONFIDENCE AND SCENARIOS:
WINDS WEDNESDAY AND THURSDAY: AS A SERIES OF UPPER LEVEL TROUGHS
EMBEDDED IN PERSISTENT UPPER LEVEL SOUTHWESTERLY FLOW MOVES
OVERHEAD, WINDS WILL INCREASE, PRIMARILY ACROSS SOUTHWESTERN MONTANA
WEDNESDAY AND THURSDAY. WHILE THE WIND INCREASE LOOKS LIKELY, THE
MAGNITUDE, EXTENT, AND DURATION OF THE WINDS ARE LIKELY TO BE QUITE
SENSITIVE TO THE EXACT TRACK OF THESE DISTURBANCES. AS OF SUNDAY,
THE NBM PROBABILITIES SEEM TO INDICATE THAT THERE ARE ROUGHLY
SIMILAR PROBABILITIES FOR WIND GUSTS OVER 45 MPH, WITH CHANCES
AROUND 50% GENERALLY CONFINED TO SOME OF THE NORTH/SOUTH ORIENTED
VALLEYS OF SOUTHWESTERN MONTANA NEAR AND SOUTH OF INTERSTATE 15.
NEXT WEEKEND: THERE ARE A FEW WAYS NEXT WEEKEND COULD PAN OUT,
LARGELY DRIVEN BY HOW STRONG AN UPPER LEVEL TROUGH GETS OVER THE
WEST COAST AND WHETHER OR NOT IT “CUTS OFF” FROM THE FLOW AND
BECOMES A CLOSED UPPER LEVEL LOW. THERE DOES SEEM TO BE A LITTLE
MORE SUPPORT FOR THE LATTER SCENARIO (AROUND 75% OF THE ENSEMBLE
MEMBERS), BUT ITS STRENGTH AND LOCATION WILL PLAY A LARGE ROLE IN
THE DETAILS OF OUR WEATHER, AND MODELS SEEM TO BE IN QUITE A BIT OF
DISAGREEMENT WITH THESE PARTICULARS. SHOULD THE LOW/TROUGH WIND UP
STAYING OFFSHORE, NEXT WEEKEND IS LIKELY TO BE A BIT ON THE WARMER
SIDE OF THE FORECAST, WITH UPPER LEVEL RIDGING BUILDING IN OVERHEAD.
HOWEVER, A MORE EASTWARD PLACEMENT OF THIS LOW/TROUGH, WHICH IS
AROUND 60% OF THE ENSEMBLE MEMBERS WOULD RESULT IN A COOLER, MORE
UNSETTLED RESULT FOR NEXT WEEKEND’S WEATHER. LUDWIG
AVIATION
31/06Z TAF PERIOD
SCATTERED MID-LEVEL CLOUD COVER ALONG AND NORTH OF THE US HWY 2
CORRIDOR WILL GRADUALLY DISSIPATE THROUGH 09-12Z MONDAY, WITH
OTHERWISE VFR CONDITIONS EXPECTED THROUGH THE 2106/0106 TAF PERIOD.
FOR KGTF: WINDS WILL REMAIN PREDOMINATELY OUT OF THE SOUTHWEST
THROUGH 21Z MONDAY, WITH THE PROBABILITY FOR CROSSWINDS BEING
EXCEEDED BELOW A 5% CHANCE. BEYOND 21Z MONDAY WINDS WILL BECOME
LIGHT AND VARIABLE. - MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 78 48 84 55 / 0 0 0 20
CTB 75 45 81 50 / 0 0 0 0
HLN 79 47 84 52 / 0 0 0 60
BZN 77 45 80 48 / 0 0 0 70
WYS 71 35 70 36 / 0 20 50 70
DLN 80 44 81 44 / 0 0 0 80
HVR 77 46 87 54 / 0 0 0 0
LWT 74 46 82 52 / 0 0 0 10
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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