691
FXUS65 KTFX 031430
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
830 AM MDT SAT MAY 3 2025
KEY MESSAGES
- AFTER THE WARMEST DAY OF THE WEEK TODAY, THE REGION TRENDS COOLER
AND WETTER SUNDAY INTO MONDAY.
- AFTER A PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS CENTRAL AND SOUTHWEST
MONTANA SUNDAY AFTERNOON, PRECIPITATION BECOMES MORE
WIDESPREAD SUNDAY NIGHT INTO MONDAY.
- SNOW LOOKS TO LARGELY BE CONFINED TO THE MOUNTAINS, THOUGH
AREAS NEAR TERRAIN WILL HAVE AT LEAST A LOW-END CHANCE FOR
SNOW SUNDAY NIGHT INTO MONDAY. RAIN IS FAVORED AT LOWER
ELEVATIONS OTHERWISE.
UPDATE
TODAY WILL BE A PLEASANT DAY WITH WARM TEMPERATURES AND LIGHT
WINDS. FOR THE UPDATE SKY GRIDS WERE ADJUSTED TO REFLECT CURRENT
OBSERVATIONS AND TRENDS. POPS WERE ADJUSTED THIS AFTERNOON TO
BETTER REFLECT THE LATEST HI-RES MODEL GUIDANCE. THE REST OF THE
FORECAST IS ON TRACK. -IG
DISCUSSION
/ISSUED 519 AM MDT SAT MAY 3 2025/
- METEOROLOGICAL OVERVIEW:
SHARP UPPER LEVEL RIDGING WILL SLOWLY SLIDE EASTWARD THROUGH THE DAY
TODAY AS UPPER LEVEL TROUGHING OFF THE WEST COAST TRUDGES EASTWARD.
THE RESULTING AMPLIFIED PATTERN WILL RESULT IN A DEEP FETCH OF
SOUTHERLY FLOW ALOFT, HELPING AFTERNOON HIGHS TODAY SOAR TO THE
HIGHEST SEEN SO FAR THIS SEASON. A DRY DAY IS FORECAST FOR THE VAST
MAJORITY, THOUGH BY THIS EVENING THE TROUGHING WILL BEGIN TO EXERT
INFLUENCE NEAR THE CONTINENTAL DIVIDE, YIELDING LOW-END SHOWER AND
THUNDERSTORM CHANCES INTO THE OVERNIGHT HOURS.
THE AFOREMENTIONED TROUGHING SPLITS HEADING INTO SUNDAY, WITH THE
STRONGER PORTION OF THE SYSTEM (CLOSED UPPER LOW) DIVING
SOUTHEASTWARD TOWARD THE DESERT SOUTHWEST. THAT SAID, THE REMAINING
TROUGHING WILL BE MORE THAN ENOUGH TO RESULT IN IMPACTS ACROSS THE
NORTHERN ROCKIES SUNDAY INTO MONDAY.
INITIAL SIGNS OF THIS SYSTEM ARRIVING SUNDAY WILL BE IN THE FORM OF
A COLD FRONT, ARRIVING INITIALLY ACROSS THE PLAINS DURING THE DAY
MORNING AND EARLY AFTERNOON SUNDAY, AND MAKING INROADS TOWARD
SOUTHWEST MONTANA LATER SUNDAY AFTERNOON INTO SUNDAY NIGHT. THE
SURFACE AIRMASS WILL REMAIN RELATIVELY WARM ACROSS PORTIONS OF
SOUTHWEST AND CENTRAL MONTANA DURING THE DAY SUNDAY, WHICH WILL
RESULT IN AT LEAST A BRIEF WINDOW FOR SHOWERS AND THUNDERSTORMS.
GUIDANCE THAT IS SLOWER WITH THE PROGRESSION OF THE COOLER SURFACE
AIRMASS FEATURES DEEP INVERTED-V SOUNDINGS IN THE AFOREMENTIONED
AREAS, WHICH WOULD FAVOR A GUSTY WIND THREAT WITH THUNDERSTORMS
THAT DO MANAGE TO FORM.
HEADING INTO SUNDAY NIGHT AS THE COLD FRONT FINALLY MAKES ITS WAY
THROUGH THE REGION, ATTENTION TURNS TOWARD A PERIOD OF MORE
STRATIFORM TYPE OF PRECIPITATION. THERE ARE STILL SOME NON-
INSIGNIFICANT DISCREPANCIES BETWEEN DETERMINISTIC GUIDANCE AND THEIR
ENSEMBLES AS TO WHERE THE BEST MID-LEVEL SUPPORT WILL BE FOR
PRECIPITATION, BUT THERE IS AGREEMENT THAT THERE WILL BE A SOUTHWEST
TO NORTHEAST ORIENTED CORRIDOR OF HIGHER PRECIPITATION AMOUNTS. AS
FOR PRECIPITATION TYPE WITH THIS SYSTEM, RAIN IS MAINLY FAVORED AT
LOWER ELEVATIONS, THOUGH AS THE HIGHEST PRECIPITATION RATES ARRIVE
LATE SUNDAY NIGHT, A BRIEF TRANSITION TO SNOW CANNOT BE RULED OUT AT
LOWER ELEVATIONS. SNOW IS FAVORED IN THE MOUNTAINS, THOUGH
CONFIDENCE IN EXACT IMPACTS FOR EACH RANGE REMAINS LOW GIVEN THE
FORECAST TRACK UNCERTAINTY.
PRECIPITATION CHANCES SLOWLY WANE MONDAY EVENING INTO TUESDAY AS
INFLUENCE FROM THE TROUGHING WANES. TEMPERATURES TREND WARMER
TUESDAY AND WEDNESDAY AS THE REGION LARGELY DRIES OUT. LOW-END
CHANCES FOR PRECIPITATION WILL BE AROUND AT TIMES NEXT WEEK, BUT
LOOKS TO BE SPOTTY AT BEST AT THIS POINT.
- FORECAST CONFIDENCE & SCENARIOS:
THE GREATEST UNCERTAINTY IN THE FORECAST CONTINUES TO BE RELATED TO
WHERE EXACTLY THE CORRIDOR OF GREATEST PRECIPITATION AMOUNTS SETS UP
SUNDAY NIGHT INTO MONDAY. THE GFS HAS A MORE SHARP CORRIDOR OF
HIGHER PRECIPITATION AMOUNTS FURTHER WEST, WHILE THE EC IS FURTHER
EAST AND MORE DIFFUSE. SNOW LEVELS ARE ALSO UNCERTAIN, SETTLING
SOMEWHERE NEAR THE HIGH PLAINS/FOOTHILLS INTERFACE. THAT SAID,
PRECIPITATION RATES MAY BRIEFLY DRAG SNOW LEVELS TO LOWER ELEVATIONS
ON THE PLAINS MONDAY MORNING.
OVERALL, GIVEN THE LOWER CONFIDENCE IN THE LOCATION OF HEAVIER
PRECIPITATION AS WELL SNOW LEVELS, NO WINTER STORM WATCHES OR
WINTER WEATHER ADVISORIES ARE WARRANTED AT THIS TIME.
THE OTHER WORTHWHILE MENTION RELATED TO UNCERTAINTY WILL BE FOR THE
TIMING OF THE COLD FRONT SUNDAY AFTERNOON AND EVENING ACROSS
SOUTHWEST MONTANA. GUIDANCE THAT IS QUICKER TO PROGRESS THE FRONT
INTO SOUTHWEST MONTANA IS QUICKER TO SHUT DOWN THE WINDOW FOR
SURFACE BASED SHOWERS AND THUNDERSTORMS. IF THIS WERE TO PAN OUT,
THE CONCERN FOR GUSTY WINDS FROM THUNDERSTORMS THAT DEVELOP WOULD
BE LOWER. -AM
AVIATION
03/12Z TAF PERIOD
EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE OVERNIGHT HOURS
TONIGHT AND INTO THE DAY ON SATURDAY AS WARM TEMPERATURES CONTINUE
THANKS TO THE FADING INFLUENCE OF AN UPPER LEVEL RIDGE. WITH THAT
SAID, A FEW SHRA MAY DEVELOP AFTER 21Z SATURDAY, THOUGH THESE
SHOULD LARGELY REMAIN OVER THE HIGH TERRAIN. WITH THAT SAID, THESE
SHRA SHOULD LARGELY REMAIN AWAY FROM TAF SITES, SO DID NOT INCLUDE
A PROB30 GROUP FOR ANY SITES AT THIS TIME. LUDWIG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 83 50 70 39 / 0 0 30 90
CTB 82 49 57 35 / 0 30 60 80
HLN 83 50 71 40 / 10 10 60 90
BZN 80 44 75 38 / 0 0 60 90
WYS 70 35 71 35 / 0 0 40 70
DLN 76 43 72 38 / 10 0 60 80
HVR 85 47 73 39 / 0 0 10 80
LWT 78 50 71 36 / 0 0 10 80
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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