556
FXUS65 KTFX 200526
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1126 PM MDT TUE MAY 19 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON
THROUGH THIS EVENING ACROSS THE REGION.
- MORE WIDESPREAD PRECIPITATION TOMORROW THROUGH THURSDAY.
- SNOW LEVELS DROP WEDNESDAY NIGHT INTO THURSDAY, ALLOWING FOR
LIGHT SNOWFALL ACCUMULATION IN THE MOUNTAINS.
- WARM AND DRY CONDITIONS ARE EXPECTED FRIDAY THROUGH THIS
WEEKEND.
DISCUSSION
/ISSUED 608 PM MDT TUE MAY 19 2026/
- METEOROLOGICAL OVERVIEW:
RESIDUAL MOISTURE FROM THE BACKSIDE OF AN UPPER LEVEL TROUGH
EXITING TO THE EAST WILL BRING SLIGHT CHANCES FOR PRECIPITATION
THIS AFTERNOON THROUGH THIS EVENING. THERE IS ENOUGH INSTABILITY
TO SUPPORT WEAK THUNDERSTORM DEVELOPMENT, ESPECIALLY IN CENTRAL
AND NORTH-CENTRAL MT. ANOTHER UPPER LEVEL TROUGH MOVES DOWN FROM
THE CANADIAN ROCKIES INTO MONTANA TOMORROW, BRINGING WIDESPREAD
WETTING PRECIPITATION. THERE WILL STILL BE ENOUGH INSTABILITY TO
WHERE A RUMBLE OF THUNDER COULD BE HEARD ACROSS THE REGION. A WEAK
COLD FRONT PASSING THROUGH TOMORROW NIGHT WILL CAUSE SNOW LEVELS
TO DROP TO AROUND 6,000 FT. THIS WILL ALLOW FOR LIGHT SNOWFALL
OVER THE MOUNTAINS AND HIGHER ELEVATION MOUNTAIN PASSES TOMORROW
NIGHT THROUGH THURSDAY MORNING. THE EXCEPTIONS ARE THE GALLATIN
AND MADISON RANGES, WHICH COULD SEE A FEW INCHES.
THURSDAY THE UPPER LEVEL TROUGH BEGINS TO MOVE SOUTHEASTWARD OUT
OF MT, ALLOWING TEMPERATURES TO BEGIN TO RISE. RIDGING BUILDS OVER
THE WESTERN CONUS THROUGH THE LATER PART OF THIS WORK WEEK INTO
THE WEEKEND, ALLOWING WARM TEMPERATURES, SUNNY SKIES, AND DRY
CONDITIONS TO PREVAIL. CURRENT MODELS ARE SHOWING BREEZY
CONDITIONS THIS WEEKEND, BUT AS OF NOW NOTHING IMPACTFUL. -DZOMBA
- FORECAST CONFIDENCE & SCENARIOS:
HI-RES MODELS ARE SHOWING PRETTY SCATTERED 15-30% CHANCES FOR
PRECIPITATION ACROSS THE REGION TODAY. IN GENERAL, MOST LOCATIONS
WILL REMAIN DRY THROUGHOUT THE DAY EXCEPT FOR WHERE THESE POP-UP
SHOWERS END UP DEVELOPING. THE HIGHEST CHANCES FOR THUNDERSTORM
ACTIVITY WILL BE ACROSS CENTRAL AND NORTH-CENTRAL MT
THERE IS STILL GOOD AGREEMENT FOR WIDESPREAD WETTING RAINS
TOMORROW. THE HEAVIEST AMOUNTS ARE CURRENTLY EXPECTED ALONG A
STRETCH FROM THE NORTHERN ROCKIES DOWN THROUGH CENTRAL MT
INCLUDING GREAT FALLS AND HELENA INTO LEWISTOWN. PROBABILITIES OF
MORE THAN 0.10" OF PRECIPITATION IN THIS AREA ARE CURRENTLY
80-100%, WHILE PROBABILITIES OF 0.25" OF PRECIPITATION ARE
CURRENTLY SITTING AT 50-70%. WHILE PRECIPITATION AMOUNTS ACROSS
THE REMAINDER OF NORTH-CENTRAL AND SOUTHWEST MT ARE NOT EXPECTED
TO BE QUITE AS HIGH, THERE IS STILL A 20-40% CHANCE FOR A TENTH OF
AN INCH OR MORE. -THOR AND DZOMBA
AVIATION
20/06Z TAF PERIOD
AN UPPER LEVEL DISTURBANCE MOVING OVER THE NORTHERN ROCKIES WILL
SPREAD PRECIPITATION FROM NORTH TO SOUTH ACROSS NORTH CENTRAL
THROUGH SOUTHWEST MONTANA, WITH VFR CIGS FALLING TO MVFR/LOW-VFR
BETWEEN 15-21Z WEDNESDAY AND THEN PERSISTING THROUGH THE REMAINDER
OF THE 2006/2106 TAF PERIOD. WHILE TERMINALS WILL PREDOMINATELY
SEE LIGHT RAIN OR RAIN SHOWERS THE KGTF, KLWT, AND KHLN TERMINALS
HAVE THE BEST OPPORTUNITY FOR AN ISOLATED THUNDERSTORMS; HOWEVER,
EVEN THESE CHANCES WERE TO LOW TO MENTION. MOUNTAIN OBSCURATION
WILL BEGIN TO INCREASE BETWEEN 09-15Z WEDNESDAY. - MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 39 56 36 60 / 20 90 60 20
CTB 38 54 33 62 / 20 70 20 10
HLN 38 63 36 61 / 10 60 90 20
BZN 33 61 33 56 / 20 30 90 50
WYS 26 56 28 51 / 10 20 90 40
DLN 34 61 33 58 / 20 10 80 30
HVR 39 61 34 65 / 30 50 10 20
LWT 35 56 33 55 / 20 80 60 40
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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