921
FXUS65 KTFX 190528
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1128 PM MDT MON MAY 18 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- IT WILL BE COLD THROUGH TUESDAY MORNING.
- ISOLATED RAIN AND SNOW SHOWERS WILL AFFECT NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA THROUGH FRIDAY WITH THE
HEAVIEST AND MOST WIDESPREAD PRECIPITATION WEDNESDAY THROUGH
THURSDAY.
- IT WILL GRADUALLY WARM UP TUESDAY AFTERNOON THROUGH THE
WEEKEND.
DISCUSSION
/ISSUED 539 PM MDT MON MAY 18 2026/
- METEOROLOGICAL OVERVIEW:
THIS AFTERNOON AN UPPER-LEVEL TROUGH REMAINS OVER NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. AS A RESULT RAIN/SNOW SHOWERS AND
COLD TEMPERATURES (WELL-BELOW) SEASONAL AVERAGES WILL LINGER ACROSS
THE AREA. THIS AFTERNOON RAIN/SNOW SHOWERS WILL PRIMARILY BE
CONFINED TO THE CONTINENTAL DIVIDE WITH A FEW ISOLATED RAIN SHOWERS
SPREADING EASTWARD TO THE PLAINS OF NORTH-CENTRAL MONTANA. ON
TUESDAY THE UPPER-LEVEL TROUGH REMAINS OVER NORTH-CENTRAL, CENTRAL,
AND SOUTHWESTERN MONTANA IN THE MORNING BEFORE NORTHWEST FLOW ALOFT
MOVES OVER THE AREA BY THE AFTERNOOON. THIS WILL KEEP COLD
TEMPERATURES ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA
TUESDAY MORNING BEFORE THEY GRADUALLY WARM UP BY TUESDAY AFTERNOON.
TUESDAY AFTERNOON THERE WILL BE ISOLATED LOWER-ELEVATION RAIN
SHOWERS AND MOUNTAIN SNOW SHOWERS DUE TO THE NORTHWEST FLOW ALOFT.
ADDITIONALLY THERE WILL BE ENOUGH INSTABILITY AROUND IN THE
AFTERNOON THAT THERE IS THE POTENTIAL FOR A FEW RUMBLES OF THUNDER.
ON WEDNESDAY AN UPPER-LEVEL TROUGH, ASSOCIATED WITH A CANADIAN COLD
FRONT, MOVES OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA.
THIS WILL BRING RAIN TO LOWER-ELEVATIONS AND SNOW TO MOUNTAIN
LOCATIONS ON WEDNESDAY. ON WEDNESDAY TEMPERATURES WILL COOL DOWN TO
SLIGHTLY BELOW SEASONAL AVERAGES. WEDNESDAY AFTERNOON SOME
INSTABILITY WILL BUILD AND ALLOW A FEW RUMBLES OF THUNDER TO OCCUR
ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. ON THURSDAY
THE UPPER-LEVEL TROUGH REMAINS OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL ALLOW COOLER TEMPERATURES WITH
WIDESPREAD PRECIPITATION TO LINGER OVER THE AREA ON THURSDAY. ON
FRIDAY NORTHWEST FLOW ALOFT MOVES OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL ALLOW TEMPERATURES TO WARM UP TO
NEAR SEASONAL AVERAGES WITH ISOLATED SHOWERS AND THUNDERSTORMS
FRIDAY AFTERNOON. ON SATURDAY AND SUNDAY AN UPPER-LEVEL RIDGE/ZONAL
FLOW BUILDS IN OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA. THIS WILL BRING WARM, MOSTLY DRY, AND WINDY WEATHER TO THE
AREA FOR MEMORIAL DAY WEEKEND. -IG
- FORECAST CONFIDENCE & SCENARIOS:
ON TUESDAY MORNING THERE IS A 30 - 70% CHANCE FOR LOW TEMPERATURES
OF 28 DEGREES OR COLDER ACROSS THE LOWER-ELEVATIONS OF NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. ON TUESDAY THERE IS A
20% CHANCE FOR THUNDER ACROSS NORTH-CENTRAL MONTANA. ON WEDNESDAY
THERE IS A 15 - 30% CHANCE FOR THUNDER ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. ON WEDNESDAY ALONG THE ROCKY
MOUNTAIN FRONT THERE IS GREATER THAN A 50 - 70% CHANCE FOR A HALF
INCH OF LIQUID PRECIPITATION. ON WEDNESDAY ALONG THE HIGHWAY 200
CORRIDOR BETWEEN GREAT FALLS AND LEWISTOWN THERE IS 25 - 40%
CHANCE FOR A HALF INCH OF LIQUID PRECIPITATION OR GREATER.
ELSEWHERE ACROSS NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA
THERE IS A 10 - 40% CHANCE FOR A QUARTER INCH OF LIQUID
PRECIPITATION OR GREATER ON WEDNESDAY. WEDNESDAY THROUGH THURSDAY
THERE IS GREATER THAN A 50% CHANCE FOR 2 INCHES OF SNOW OR GREATER
ACROSS THE MOUNTAINS OF NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA. ON SATURDAY AND SUNDAY THERE IS A 20 - 50% CHANCE FOR
WIND GUSTS OF 40 MPH OR GREATER. -IG
AVIATION
19/06Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE DURATION OF THE
1906/2006 TAF PERIOD; HOWEVER, WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS WILL DEVELOP BETWEEN 16-19Z TUESDAY AND
PERSIST THROUGH 03-06Z WEDNESDAY ACROSS SOUTHWEST THROUGH NORTH
CENTRAL MONTANA. MAIN IMPACT FROM ANY SHOWER OR STORM WILL BE
ERRATIC WINDS AND BRIEF REDUCTIONS IN CIGS TO LOW-VFR, ALONG WITH
MOUNTAIN OBSCURATION. - MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 30 64 40 56 / 0 40 20 70
CTB 29 63 37 53 / 30 20 30 90
HLN 30 65 38 60 / 10 30 30 40
BZN 24 62 33 60 / 0 0 30 20
WYS 15 54 25 54 / 0 10 20 20
DLN 25 61 33 61 / 0 10 20 10
HVR 28 68 40 60 / 0 40 60 50
LWT 26 60 36 56 / 0 20 30 70
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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