145
FXUS65 KTFX 161943
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
143 PM MDT SAT MAY 16 2026
KEY MESSAGES
- RAIN AND SNOW SHOWERS WILL AFFECT THE AREA THIS AFTERNOON
THROUGH MONDAY MORNING.
- IT WILL BE COLD THIS AFTERNOON THROUGH TUESDAY MORNING.
- IT WILL GRADUALLY WARM UP TUESDAY THROUGH THE END OF THE WORK
WEEK WITH ISOLATED SHOWERS AROUND.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
THIS AFTERNOON AN UPPER-LEVEL TROUGH ASSOCIATED WITH A SURFACE
PACIFIC COLD FRONT BEGINS TO MOVE OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL BRING RAIN AND SNOW SHOWERS AND
COOLER TEMPERATURES TO THE AREA THIS AFTERNOON. AHEAD OF THE COLD
FRONT IN SOUTHWESTERN MONTANA INSTABILITY WILL BUILD THIS AFTERNOON.
THIS WILL LEAD TO A FEW RUMBLES OF THUNDER ACROSS SOUTHWESTERN
MONTANA THIS AFTERNOON. A CANADIAN COLD FRONT WILL MOVE SOUTH FROM
CANADA TONIGHT. ON SUNDAY THE UPPER-LEVEL TROUGH REMAINS OVER NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS COMBINED WITH THE
CANADIAN COLD FRONT WILL BRING WELL-BELOW SEASONAL AVERAGES FOR
TEMPERATURES ON SUNDAY. ON SUNDAY THERE WILL BE WIDESPREAD
PRECIPITATION ACROSS THE AREA. ACROSS MOUNTAIN LOCATIONS THIS WILL
BE SNOW. AT LOWER-ELEVATIONS THIS WILL BE A RAIN/SNOW MIX WITH SOME
LOWER-ELEVATION LOCATIONS SEEING ALL SNOW. SUNDAY AFTERNOON THERE IS
ENOUGH INSTABILITY AROUND THAT THERE IS THE POTENTIAL FOR A FEW
RUMBLES OF THUNDER AS WELL.
ON MONDAY THE UPPER-LEVEL TROUGH REMAINS OVER NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA. AS A RESULT PRECIPITATION AND
COLD TEMPERATURES (WELL-BELOW SEASONAL AVERAGES) WILL LINGER
ACROSS THE AREA. ON TUESDAY THE UPPER-LEVEL TROUGH REMAINS OVER
NORTH- CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA IN THE MORNING
BEFORE AN UPPER-LEVEL RIDGE BUILDS 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. ON WEDNESDAY AN UPPER-
LEVEL TROUGH BUILDS BACK IN OVER NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. THIS WILL BRING ISOLATED RAIN SHOWERS AT
LOWER-ELEVATIONS AND SNOW SHOWERS AT MOUNTAIN LOCATIONS ON
WEDNESDAY WITH ABOUT SEASONAL AVERAGES FOR TEMPERATURES. ON
THURSDAY AND FRIDAY AN UPPER-LEVEL RIDGE BUILDS IN OVER NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THIS WILL ALLOW
TEMPERATURES TO WARM UP WITH MOSTLY DRY WEATHER. -IG
- FORECAST CONFIDENCE & SCENARIOS:
SUNDAY THROUGH MONDAY THERE IS A 10 - 50% CHANCE FOR GREATER THAN A
TENTH OF AN INCH OF SNOW ACROSS THE LOWER-ELEVATIONS OF NORTH-
CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA SOUTH OF THE MONTANA 200
CORRIDOR. ACROSS THE MOUNTAINS OF NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA THERE IS A 50 - 80% CHANCE FOR 4 INCHES OF SNOW
OR GREATER. AS A RESULT WINTER WEATHER ADVISORIES HAVE BEEN ISSUED
FOR MOST OF THE MOUNTAIN AREAS. AN AREA OF UNCERTAINTY IS WHEN THE
COLD AIR MOVES IN AND TRANSITIONS RAIN TO SNOW OR A RAIN/SNOW MIX AT
LOWER-ELEVATIONS. THERE IS GREATER THAN A 25% CHANCE FOR A QUARTER
INCH OF LIQUID PRECIPITATION OR GREATER ACROSS NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA FROM THIS EVENING THROUGH MONDAY
MORNING.
ON SUNDAY MORNING ACROSS THE LOWER-ELEVATIONS OF SOUTHWESTERN
MONTANA THERE IS GREATER THAN A 50% CHANCE FOR LOW TEMPERATURES OF
28 DEGREES OR COLDER. ON SUNDAY ACROSS MOST OF THE LOWER-ELEVATIONS
OF NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA THERE IS GREATER
THAN A 50% CHANCE FOR HIGH TEMPERATURES OF 45 DEGREES OR COLDER. ON
MONDAY AND 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. -IG
AVIATION
16/18Z TAF PERIOD
A MIX OF RAIN AND MOUNTAIN SNOW WILL CONTINUE ACROSS PORTIONS OF THE
REGION THIS AFTERNOON, MOSTLY ACROSS CENTRAL AND SOUTHWEST
MONTANA. A FEW THUNDERSTORMS WILL DEVELOP THIS AFTERNOON, BUT
CONFIDENCE IN ONE OF THESE IMPACTING A TERMINAL WAS TOO LOW TO
MENTION IN TAFS AT THIS TIME.
SNOW SLOWLY BECOMES THE FAVORED PRECIPITATION TYPE LATER TONIGHT AND
INTO TOMORROW IN MANY AREAS, PARTICULARLY BEHIND A COLD FRONT
ARRIVING FROM NORTH TO SOUTH SUNDAY MORNING AND AFTERNOON. MOUNTAINS
WILL BECOME INCREASINGLY OBSCURED THROUGH THE TAF PERIOD. -AM
PRELIMINARY POINT TEMPS/POPS
GTF 31 40 27 52 / 30 80 40 10
CTB 30 38 25 55 / 50 70 10 0
HLN 32 43 30 54 / 30 70 30 10
BZN 28 45 28 49 / 90 30 30 20
WYS 23 37 21 43 / 50 20 20 10
DLN 25 45 23 50 / 40 40 20 0
HVR 35 44 29 53 / 50 80 50 10
LWT 30 39 27 45 / 90 70 60 40
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
SUNDAY NIGHT FOR BIG BELT, BRIDGER AND CASTLE MOUNTAINS-EAST
GLACIER PARK REGION-ELKHORN AND BOULDER MOUNTAINS-LITTLE BELT
AND HIGHWOOD MOUNTAINS-SOUTHERN ROCKY MOUNTAIN FRONT-UPPER
BLACKFOOT AND MACDONALD PASS.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM MDT
SUNDAY FOR GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL
MOUNTAINS.
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