050
FXUS65 KTFX 171937
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
137 PM MDT SUN MAY 17 2026
KEY MESSAGES
- PRECIPITATION LARGELY SUBSIDE THIS EVENING.
- TWO COLD NIGHTS AHEAD, WITH LOWS IN THE 20S FOR MANY AREAS.
- SLOWLY TRENDING WARMER THROUGH THE WEEK, WITH A FEW ROUNDS OF
PRECIPITATION AT TIMES.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
THE CORE OF THE UPPER LEVEL TROUGHING IS BEGINNING TO TRACK EAST OF
THE REGION THIS AFTERNOON, RESULTING IN A NORTHERLY FLOW ALOFT.
NORTHERLY/NORTHWESTERLY UPSLOPE PRECIPITATION CONTINUES THIS
AFTERNOON, WITH ADDITIONAL PRECIPITATION DEVELOPING IN THE FORM OF
SHOWERS, MAINLY ACROSS SOUTHWEST MT AND VICINITY.
LOSS OF DAYTIME HEATING AND UPSLOPE FLOW WILL ALLOW FOR
PRECIPITATION TO COME TO AN END THIS EVENING. LIGHTER NORTHERLY
FLOW ALOFT CONTINUES INTO TONIGHT THOUGH, WHICH WILL ALLOW FOR
QUITE A COLD NIGHT ACROSS THE REGION. MOST LOCATIONS LOOK TO FALL
INTO THE 20S, WITH A FEW COLD PRONE LOCATIONS DIPPING INTO THE
TEENS. SOME PATCHY FOG CANNOT BE RULED OUT TONIGHT, THOUGH
COVERAGE WILL DEPEND ON WHERE MOST PRECIPITATION FALLS THROUGH THE
REMAINDER OF THE DAY TODAY.
COOL AIR ALOFT PERSISTS INTO MONDAY, WHICH WILL COMBINE WITH DAYTIME
HEATING TO RESULT IN A MIX OF RAIN AND SNOW SHOWERS ACROSS THE
REGION. SLIGHTLY WARMER AIR ALOFT BEGINS TO MOVE IN MONDAY NIGHT,
THOUGH LINGERING COOLER AIR AT THE SURFACE WILL RESULT IN ANOTHER
COLD NIGHT BEFORE TEMPERATURES TREND CLOSER TO AVERAGE DURING THE
DAY TUESDAY. A FEW AFTERNOON SHOWERS WILL BE AROUND TUESDAY, BUT
OVERALL COVERAGE OF THE SHOWERS IS QUESTIONABLE AT THIS TIME.
SEVERAL DISTURBANCES PASS ACROSS THE REGION WITHIN A NORTHWEST FLOW
ALOFT WEDNESDAY ONWARD, WHICH WILL ALLOW FOR A COUPLE STRETCHES OF
PRECIPITATION. TEMPERATURES OVER THIS TIMEFRAME SLOWLY TREND WARMER,
THOUGH THIS TREND WILL BE BRIEFLY INTERRUPTED BY THE SHOWERY
CONDITIONS AT TIMES. -AM
- FORECAST CONFIDENCE & SCENARIOS:
COLD TEMPERATURES TONIGHT AND MONDAY NIGHT:
THE PROBABILITY FOR AN OVERNIGHT LOW BELOW 32F IS NEARLY 100% IN ALL
AREAS TONIGHT. THAT PROBABILITY ISN'T QUITE AS HIGH FOR MONDAY NIGHT,
BUT IS AT OR GREATER THAN 50% IN THE OVERWHELMING MAJORITY OF AREAS.
PRECIPITATION WEDNESDAY:
A SHARPER TROUGH LOOKS TO PASS ACROSS THE REGION WEDNESDAY INTO
WEDNESDAY NIGHT. THIS TROUGH LOOKS COOL ENOUGH TO RESULT IN SOME
MOUNTAIN SNOW, BUT MOST PRECIPITATION LOOKS TO FALL AS RAIN. AREAS
ALONG THE ROCKY MOUNTIAN FRONT AND ACROSS CENTRAL MONTANA TERRAIN
HAVE A ROUGHLY 30% PROBABILITY FOR 0.25" LIQUID FROM THIS SYSTEM. -AM
AVIATION
17/18Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL AT THE KBZN, KEKS, AND KWYS TERMINALS
DURING THIS TAF PERIOD. AT THE KBZN AND KEKS TERMINALS BETWEEN
17/18Z AND 18/02Z THERE IS A 15 - 20% CHANCE FOR RAIN AND SNOW
SHOWERS AND THUNDERSTORMS. A THE KHLN TERMINAL THERE IS A 30 - 40%
CHANCE FOR RAIN AND SNOW SHOWERS AND A 15 - 20% CHANCE FOR
THUNDER BETWEEN 17/18Z AND 17/24Z. AT THE KGTF AND KCTB TERMINALS
THERE IS A 15 - 40% CHANCE FOR RAIN AND SNOW SHOWERS BETWEEN
18/00Z AND 18/06Z. AT THE KLWT TERMINAL DURING THE MAJORITY OF
THIS TAF PERIOD THERE IS AT LEAST A 15 - 40% FOR RAIN AND SNOW
SHOWERS. ANY THUNDERSTORMS WILL PRODUCE GUSTY, ERRATIC WINDS AND
FREQUENT LIGHTNING. AT ANY SITES THAT CLEAR THERE IS A VERY LOW
CHANCE FOR PATCHY FOG TO FORM WHICH IS TOO LOW TO INCLUDE IN ANY
TAF AT THIS TIME. DURING THE MAJORITY OF THIS TAF PERIOD THERE
WILL BE MOUNTAIN OBSCURATION ACROSS NORTH-CENTRAL, CENTRAL, AND
SOUTHWESTERN MONTANA. -IG
PRELIMINARY POINT TEMPS/POPS
GTF 28 53 30 65 / 40 10 0 10
CTB 24 54 30 63 / 20 10 10 20
HLN 31 56 32 65 / 20 10 0 0
BZN 25 51 25 61 / 20 20 10 0
WYS 21 44 18 54 / 10 10 10 0
DLN 25 51 26 60 / 20 10 0 0
HVR 27 55 28 68 / 40 10 0 0
LWT 27 47 25 60 / 60 30 10 10
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT 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.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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