545
FXUS65 KTFX 082012
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
212 PM MDT TUE SEP 8 2026
KEY MESSAGES
- RAIN WILL GRADUALLY END ALONG THE HI-LINE THIS EVENING.
- IT WILL BE DRY AND BREEZY ON WEDNESDAY AND THURSDAY.
- PRECIPITATION AND COOLER TEMPERATURES RETURN FRIDAY THROUGH
THIS WEEKEND.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
AN UPPER-LEVEL TROUGH IS MOVING OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA THIS AFTERNOON. AS A RESULT RAIN SHOWERS WILL
LINGER ACROSS THE HI-LINE THROUGH THIS EVENING WITH COOLER
TEMPERATURES ACROSS THE AREA. ON WEDNESDAY AN UPPER-LEVEL RIDGE
MOVES OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS
WILL BRING DRY AND WARM TEMPERATURES (NEAR SEASONAL AVERAGES) TO THE
AREA ON WEDNESDAY. ON WEDNESDAY 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 AN UPPER-LEVEL TROUGH 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) TO THE AREA. ON FRIDAY THERE WILL BE RAIN SHOWERS ACROSS
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. SATURDAY THROUGH
MONDAY THERE WILL BE AN UPPER-LEVEL CLOSED LOW THAT WILL BRING
COOLER TEMPERATURES AND WIDESPREAD PRECIPITATION TO THE AREA. HIGHER
ELEVATION LOCATIONS HAVE THE POTENTIAL TO RECEIVE SNOW THIS WEEKEND.
SEE THE FORECAST CONFIDENCE & SCENARIOS SECTION FOR DETAILS. -IG
- FORECAST CONFIDENCE & SCENARIOS:
ON WEDNESDAY THERE IS A 60 - 80% CHANCE FOR WIND GUSTS OF 40 MPH OR
GREATER. ON THURSDAY THERE IS GREATER THAN A 60% CHANCE FOR WIND
GUSTS OF 40 MPH OR GREATER ACROSS THE ROCKY MOUNTAIN FRONT AND
PLAINS WEST OF 1-15, THE HI-LINE, CASCADE TO JUDITH BASIN COUNTY,
AND THE NORTH-SOUTH ORIENTATED VALLEYS OF SOUTHWESTERN MONTANA. ON
THURSDAY ALONG THE ROCKY MOUNTAIN FRONT THERE IS A 60 - 80% CHANCE
FOR WIND GUSTS OF 55 MPH OR GREATER.
SATURDAY THROUGH MONDAY DETERMINISTIC AND ENSEMBLE MODELS DIFFER ON
THE TRACK AND STRENGTH OF THE UPPER-LEVEL TROUGH/CLOSED-LOW. ON
SATURDAY TWO CLUSTERS HAVE A CLOSED UPPER-LEVEL LOW IN THE VICINITY
OF WASHINGTON/OREGON. THIS SCENARIO WOULD KEEP TEMPERATURES SIMILAR
TO FRIDAY WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS ACROSS
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. ON SATURDAY ONE
CLUSTER HAS AN UPPER-LEVEL TROUGH OVER EASTERN WASHINGTON AND
OREGON. THIS SCENARIO WOULD KEEP SIMILAR WEATHER TO THE CLOSED LOW
SCENARIO BUT IT WOULD BE SLIGHTLY LESS WINDY. A THIRD CLUSTER HAS A
UPPER-LEVEL TROUGH OVER MONTANA. THIS SCENARIO WOULD BRING COOLER
TEMPERATURES AND WIDESPREAD PRECIPITATION ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. ON SUNDAY THREE OUT OF FOUR
CLUSTERS HAVE AN UPPER-LEVEL TROUGH OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS SCENARIO WOULD BRING COOL TEMPERATURES
AND WIDESPREAD PRECIPITATION TO NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. ON SUNDAY THE FOURTH CLUSTER HAS A CLOSED
UPPER-LEVEL LOW OFF THE COAST OF WASHINGTON/OREGON WITH AN UPPER-
LEVEL RIDGE OVER MONTANA. THIS WOULD BRING WARM AND MOSTLY DRY
WEATHER TO NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS
ALL SHOWS THAT THIS WEEKEND THROUGH MONDAY THERE IS HIGH UNCERTAINTY
IN THE OVERALL WEATHER PATTERN. HOWEVER, IN WHICHEVER SCENARIO PANS
OUT THERE IS AT LEAST A MODERATE CHANCE FOR SNOW ACROSS THE
HIGHER PEAKS OF NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA
THIS WEEKEND. -IG
AVIATION
08/18Z TAF PERIOD
RAIN SHOWERS WILL CONTINUE OVER NORTH-CENTRAL MT THROUGH THIS
AFTERNOON, DISSIPATING AROUND 21Z FOR KCTB AND 01Z FOR KHVR. THERE
IS A CHANCE OF WEAK THUNDERSTORMS OVER KBZN FROM 22Z TO 01Z. NEAR
ANY SHOWERS AND WEAK THUNDERSTORMS, MOUNTAIN OBSCURATION IS
POSSIBLE. VFR CONDITIONS WILL PREVAIL THROUGHOUT THIS TAF PERIOD
WITH THE EXCEPTION OF KHVR, WHICH COULD SEE MVFR VISBILITIES
THROUGH 01Z.
FOR KGTF: DUE TO THE VARYING WIND DIRECTIONS, A TEMPO GROUP WAS
ADDED WITH -SHRA TO REFLECT THE SPORADIC NATURE OF THE WINDS, AS
WELL AS THE POTENTIAL FOR LIGHT SHOWERS NEAR THE TERMINAL. WHILE
VFR CONDITIONS WILL PREVAIL THROUGHOUT THIS TAF PERIOD, CLOUD
DECKS WILL REMAIN LOW, NEAR MVFR LEVELS AT TIMES, THROUGH THE
AFTERNOON, BEFORE BEGINNING TO LIFT AROUND 00Z. DUE TO THE STRONG
NORTHWESTERLY COMPONENT OF THE WIND, THERE IS HIGH CONFIDENCE OF
PERIODIC WIND GUSTS EXCEEDING THE CROSS-WIND THRESHOLD THROUGH
02Z, AT WHICH A SOUTHWESTERLY WIND SHIFT WILL CREATE A LESS THAN
10% CHANCE OF THE CROSS-WIND THRESHOLD BEING EXCEEDED. -DZOMBA
PRELIMINARY POINT TEMPS/POPS
GTF 44 76 54 81 / 10 0 0 0
CTB 44 69 50 72 / 10 0 0 0
HLN 42 76 49 84 / 0 0 0 0
BZN 39 77 45 84 / 0 0 0 0
WYS 30 70 30 72 / 0 0 0 0
DLN 37 78 41 81 / 0 0 0 0
HVR 43 75 49 81 / 40 0 0 0
LWT 41 73 50 82 / 20 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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