883
FXUS65 KTFX 161115
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
515 AM MDT TUE JUN 16 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- WARM AND WINDY CONDITIONS DEVELOP BY THIS AFTERNOON FOLLOWED
BY SHOWERS AND THUNDERSTORMS WITH LOCALIZED STRONG WINDS, HAIL,
AND DOWNPOURS MOVING SOUTHWARD THROUGH THE PLAINS THIS EVENING.
- COOLER, SHOWERY, AND BREEZY TO WINDY CONDITIONS MOVE IN
ON WEDNESDAY, ESPECIALLY FOR CENTRAL AND NORTH-CENTRAL MONTANA.
- THE WORKWEEK WILL FINISH WITH A WARMING AND DRYING TREND BEFORE
SHOWER AND THUNDERSTORM ACTIVITY INCREASES AGAIN AND
TEMPERATURES COOL DOWN THIS WEEKEND.
DISCUSSION
/ISSUED 220 AM MDT TUE JUN 16 2026/
- METEOROLOGICAL OVERVIEW:
A WEAK SHORTWAVE EMBEDDED WITHIN A NORTHWESTERLY FLOW HAS BROUGHT
SOME LIGHT SHOWER ACTIVITY TO THE MILK RIVER VALLEY THIS MORNING.
THIS ACTIVITY SHOULD QUICKLY MOVE OFF TO THE EAST BY DAWN. THEN
THE FOCUS WILL SHIFT TO THE 45 TO 55 KT H700 JET STREAK THAT WILL
PASS THROUGH LATER THIS AFTERNOON. THE COMBINATION OF THIS WITH
DEEP LAYER MIXING WILL RESULT IN WINDY, WARM, AND DRY CONDITIONS
FOR VIRTUALLY THE ENTIRE FORECAST AREA. AREAS ALONG THE ROCKY
MOUNTAIN FRONT SOUTHWARD TO MACDONALD PASS, THE PLAINS WEST OF
I15, AND PORTIONS OF THE CENTRAL MT HIGHWAY 87/200 WILL SEE THE
STRONGEST WINDS FOR THE LONGEST PERIOD. THERE WILL ALSO BE SOME
INSTANCES OF GUSTS EXCEEDING 50 TO 55 MPH OVER AND NEAR THE BIG
BELT MOUNTAINS AND SOME OF THE HIGHER PEAKS IN SOUTHWEST MT.
RELATIVE HUMIDITIES WILL FALL TO NEAR CRITICAL LEVELS WHILE
TEMPERATURES WARM INTO THE 80S. THIS WILL CAUSE SOME LOCALIZED
FIRE WEATHER CONDITIONS, MOSTLY FOR SOUTHWEST MT WHERE THE FUELS
ARE SOMEWHAT DRIER.
A CANADIAN COLD FRONT AND ASSOCIATED SHOWERS AND THUNDERSTORMS
MOVE SOUTHWARD THROUGH CENTRAL AND NORTH-CENTRAL MT LATE THIS
AFTERNOON THROUGH TONIGHT. CAPE VALUES FOR THIS TIME PERIOD STILL
LOOK TO REMAIN AROUND 200 TO 500 J/KG; HOWEVER, BULK SHEAR WILL
GENERALLY BE OVER 40 KTS AND WILL BE SUPPORTIVE OF LOCALIZED
STRONG WIND GUSTS, HAIL, AND DOWNPOURS, ESPECIALLY DURING THE
EVENING HOURS.
GUSTY NORTHWESTERLY WINDS AND SCATTERED SHOWER/THUNDERSTORM
ACTIVITY LINGER ON THE BACKSIDE OF THIS SYSTEM THROUGH WEDNESDAY
EVENING. GENERAL UNSETTLED CONDITIONS CONTINUE FOR THE REMAINDER
OF THE SECOND HALF OF THE WORKWEEK, THOUGH IT WILL BE DRIER AND
WARMER HEADING TOWARDS THE FIRST HALF OF THE WEEKEND. THERE ARE
SOME DISAGREEMENTS WITH THE PRECISE DETAILS FOR THIS WEEKEND, BUT
THERE IS AGREEMENT WITH SHORTWAVES INTERACTING WITH ML CAPE VALUES
ABOVE 500 J/KG FOR INCREASED SHOWER AND THUNDERSTORM ACTIVITY
SOMETIME SATURDAY INTO SUNDAY. TEMPERATURES ALSO LOOK TO WARM
CLOSER TO AVERAGE FRIDAY AND SATURDAY BEFORE COOLING OFF AGAIN
SUNDAY INTO EARLY NEXT WEEK. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
WINDY, WARM, AND DRY CONDITIONS TODAY FOLLOWED BY EVENING
THUNDERSTORMS...
WESTERLY WINDS INCREASE SIGNIFICANTLY IN ADVANCE OF AN
APPROACHING TROUGH AND COLD FRONT TODAY. THE NAEFS ANOMALY INDEX
HAS H700/H500 WINDS APPROACHING THREE STANDARD DEVIATIONS ABOVE
CLIMATOLOGY AND THE EC EFI IS NOW RUNNING BETWEEN .7 AND .9 FOR
ANOMALOUSLY STRONG WINDS OVER THE PLAINS WESTWARD TO THE ROCKY
MOUNTAIN FRONT. VALUES APPROACHING 1.0 SUGGEST HIGHLY UNUSUAL
STRONG WINDS FOR THIS TIME OF YEAR WHEN COMPARED TO CLIMATOLOGY.
NBM PROBABILITIES ARE ALSO INCREASING WITH THE CHANCE FOR 55 MPH +
GUSTS NOW RUNNING IN THE 70 TO 90% RANGE FOR AREAS ALONG THE
ROCKY MOUNTAIN FRONT SOUTHWARD TO MACDONALD PASS, THE PLAINS WEST
OF I15, PORTIONS OF THE CENTRAL MT HIGHWAY 87/200, AND OVER THE
BIG BELT/BRIDGER RANGES.
THERE IS STILL SOME UNCERTAINTY ON WHETHER THESE WINDS WILL
PERSIST FOR LONGER THAN A THREE HOUR PERIOD, BUT IT'S LOOKING MORE
LIKE THE ANSWER TO THIS QUESTION IS TRENDING TOWARDS YES GIVEN
H700 WINDS RAMPING UP BY THE EARLY AFTERNOON HOURS. ALSO MODEL
GUIDANCE CONTINUES TO HOLD THE CANADIAN FRONT NORTH OF THE
INTERNATIONAL BORDER THROUGH AT LEAST 6 PM THIS EVENING. IT WOULD
TAKE EARLY THUNDERSTORM INITIATION TO BRING IT SOUTHWARD SOONER
WHICH WOULD RESULT INCREASED INSTANCES OF CONVECTIVELY DRIVEN
STRONG WINDS. GIVEN THESE FACTORS, I OPTED TO GO WITH A HIGH WIND
WARNING FOR THESE AFOREMENTIONED AREAS. TECHNICALLY, I COULD LEAVE
THE ROCKY MOUNTAIN FRONT ZONES OUT OF THE WARNING SINCE 75 MPH
GUSTS ARE NOT EXPECTED, BUT IT'S THE WARM SEASON NOW AND THERE
WILL BE MORE ONGOING ACTIVITIES COMPARED TO THE TYPICAL HIGH WIND
SEASON WHEN WINDS GUST IN THE 55 TO 65 MPH RANGE OCCUR REGULARLY.
NOTE THAT AREAS OUTSIDE OF THESE WARNINGS WILL BE WINDY AS WELL
AND MAY EVEN OBSERVE SOME ISOLATED CRITERIA GUSTS OR SUSTAINED
WINDS.
SHOWERS AND THUNDERSTORMS WILL MOVE FROM NORTH TO SOUTH THROUGH
CENTRAL/NORTH-CENTRAL MT LATE THIS AFTERNOON THROUGH THE EARLY
OVERNIGHT HOURS. THUNDERSTORM HAZARDS MAY INCLUDE LOCALIZED STRONG
WIND GUSTS, HAIL, AND DOWNPOURS. THIS ACTIVITY WILL BE MOST
WIDESPREAD ALONG THE HI-LINE, ESPECIALLY OVER HILL AND BLAINE
COUNTIES. WITH THAT BEING SAID ANY CENTRAL/NORTH-CENTGRAL LOCATION
WILL BE SUSCEPTIBLE TO ISOLATED INSTANCES OF THESE HAZARDS.
THE PRIMARY IMPACT FROM TODAY'S WINDS AND SUBSEQUENT
SHOWER/THUNDER ACTIVITY STILL LOOKS BE INCLEMENT OUTDOOR
RECREATION AND DIFFICULT TRAVEL FOR THOSE OPERATING HIGH PROFILE
VEHICLES. ALSO, IT'S IMPORTANT TO NOTE THE COMBINATION OF
TEMPERATURES WARMING WELL INTO THE 80S AND RHS FALLING TO NEAR
CRITICALLY LOW LEVELS THIS AFTERNOON MAY RESULT IN LOCALIZED
ELEVATED FIRE WEATHER CONDITIONS, MOSTLY FOR SOUTHWESTERN
LOCATIONS THAT HAVE MISSED OUT ON THE RAINFALL OR ARE HAVING A
POOR GREENUP.
GUSTY NORTHWESTERLY WINDS AND LINGERING SCATTERED SHOWERS AND
THUNDERSTORMS ON WEDNESDAY...
THE WINDS WILL SHIFT TO A MORE NORTHWESTERLY DIRECTION ON
WEDNESDAY AND WILL GENERALLY BE STRONGEST OVER THE PLAINS EAST OF
I15, ESPECIALLY ALONG THE HI-LINE AND OVER PORTIONS OF FERGUS
COUNTY. SHOWERS AND THUNDERSTORMS WILL MOSTLY BE CONCENTRATED OVER
CENTRAL/NORTH-CENTRAL MT AGAIN AND WILL GENERALLY BE WEAK;
HOWEVER, THEY WILL BE CAPABLE OF TRANSFERRING THE STRONGER 40 TO
50 KT WINDS ALOFT TO THE SURFACE AT TIMES. - RCG
AVIATION
16/12Z TAF PERIOD
GUSTY TO STRONG WESTERLY WINDS DEVELOP BY THIS AFTERNOON FOR MUCH
OF THE FORECAST AREA. THIS WILL BE ACCOMPANIED BY MOUNTAIN WAVE
TURBULENCE AND INSTANCES OF LOW LEVEL WIND SHEAR. SCATTERED
SHOWERS AND THUNDERSTORMS WILL DEVELOP FROM NORTH TO SOUTH AFTER
16/20Z AND WILL MOSTLY IMPACT THE PLAINS TERMINALS THROUGH AROUND
17/08Z. LOCALIZED ERRATIC WIND GUSTS, HAIL, AND BRIEF DOWNPOURS
WILL ACCOMPANY THE STRONGER CELLS. GENERAL VFR CONDITIONS WILL
PREVAIL, BUT LOWER VFR AND SOME MVFR CLOUDS WILL BECOME MORE
WIDESPREAD OVER THE PLAINS AFTER 17/00Z. - RCG
PRELIMINARY POINT TEMPS/POPS
GTF 86 50 71 46 / 10 50 40 40
CTB 80 45 67 43 / 40 70 50 50
HLN 86 52 75 47 / 0 0 20 0
BZN 88 52 75 44 / 0 0 10 0
WYS 82 40 73 34 / 0 0 0 0
DLN 86 48 77 42 / 0 0 0 0
HVR 85 48 70 43 / 50 60 40 20
LWT 82 45 65 41 / 10 90 20 20
TFX WATCHES/WARNINGS/ADVISORIES
HIGH WIND WARNING FROM NOON TODAY TO MIDNIGHT MDT TONIGHT FOR
BIG BELT, BRIDGER AND CASTLE MOUNTAINS-EAST GLACIER PARK REGION-
EASTERN GLACIER, WESTERN TOOLE, AND CENTRAL PONDERA-JUDITH BASIN
COUNTY AND JUDITH GAP-NORTHERN HIGH PLAINS-SOUTHERN HIGH PLAINS-
SOUTHERN ROCKY MOUNTAIN FRONT-UPPER BLACKFOOT AND MACDONALD PASS.
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