127
FXUS65 KTFX 050837
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
237 AM MDT MON MAY 5 2025
KEY MESSAGES
- PRECIPITATION SLOWLY COMES TO AND END FROM NORTH TO SOUTH ACROSS
THE REGION TODAY INTO TONIGHT.
- SNOW LEVELS LARGELY LOOK TO BE CONFINED TO NEAR AND ABOVE PASS
LEVEL, BUT WILL FALL TO PORTIONS OF THE PLAINS AND VALLEY
FLOORS THIS MORNING AND AGAIN TOWARD TONIGHT.
- TRENDING WARMER AND LARGELY DRIER THROUGH THE REST OF THE WEEK.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
SPLIT TROUGHING IS IN PLACE ACROSS THE WEST, WITH CLOSED LOW OVER AZ
AND VICINITY AND AN OPEN WAVE OVER WESTERN MT AND VICINITY.
PRECIPITATION MUCH OF THE OVERNIGHT THUS FAR HAS BEEN FRONTOGENETIC
IN NATURE, EVIDENT BY THE TIGHTENING TEMPERATURE GRADIENT THROUGH
06Z AT 700 MB. FRONTOGENETIC FORCING SLOWLY DIMINISHES THE REMAINDER
OF THE OVERNIGHT, THOUGH INCREASING NORTHERLY TO NORTHEASTERLY
UPSLOPE WINDS WILL ATTEMPT TO PICK UP THE SLACK THROUGH THE DAY
TODAY. THIS WILL KEEP PRECIPITATION IN THE FORECAST FOR MOST OF THE
DAY, SLOWLY ENDING FROM NORTHWEST TO SOUTHEAST BEGINNING THIS
AFTERNOON, FINALLY ENDING TOMORROW MORNING. SNOW LEVELS LARGELY LOOK
TO BE AROUND AND A BIT BELOW PASS LEVEL, THOUGH DO LOOK TO
BRIEFLY LOWER ONTO THE PLAINS AND INTO VALLEYS THIS MORNING AS
WELL AS HEADING INTO TONIGHT AS COOLER AIR WORKS IN.
THE UPPER CLOSED LOW AND TROUGHING SHIFT FAR ENOUGH AWAY FROM THE
REGION TOMORROW TO INITIATE A WARMING TREND INTO WEDNESDAY.
OUTSIDE OF EASTERN AREAS TOMORROW, THE REGION IS LOOKING DRY OVER
THIS TIMEFRAME. MORNING LOWS DO LOOK TO REMAIN ON THE CHILLY
SIDE, HOWEVER.
A WEAK SYSTEM TRAVERSING A DEVELOPING WESTERLY TO SOUTHWESTERLY FLOW
ALOFT THURSDAY WILL INTRODUCE LOW-END CHANCES FOR SHOWERS AND
PERHAPS A FEW THUNDERSTORMS, MAINLY IN THE MOUNTAINS.
THEREAFTER A BUILDING TROUGH OFF THE PACIFIC COASTLINE BRINGS ABOUT
UNCERTAINTY TOWARD THIS WEEKEND. ENSEMBLES ARE ON THE WARMER SIDE
FOR BOTH SATURDAY AND SUNDAY, WHILE RECENT DETERMINISTIC GUIDANCE
HAS TRENDED MUCH COOLER FOR SUNDAY. BOTH SOLUTIONS WOULD FEATURE AT
LEAST LOW-END OPPORTUNITIES FOR SHOWERS AND THUNDERSTORMS. -AM
- FORECAST CONFIDENCE & SCENARIOS:
CONFIDENCE IN PRECIPITATION IS HIGH FOR THE UPCOMING 24 HOURS OR
SO, BUT CONFIDENCE IN SNOW LEVELS IS MUCH LOWER. SO FAR THIS
MORNING WHERE PRECIPITATION RATES HAVE BEEN HEAVIEST, SNOW LEVELS
HAVE FALLEN TO AT LEAST 4,200 FT (GEYSER AREA), AND PERHAPS LOWER.
THESE AREAS HAVE BEEN UNDER THE STRONGEST BANDED PRECIPITATION
HOWEVER, WHICH LEADS TO LOWER CONFIDENCE IN THESE SNOW LEVELS
BEING THAT LOW OVER THE ENTIRE REGION.
NONETHELESS, ANOTHER SHOT OF COOLER AIR ARRIVES FROM THE NORTH THIS
MORNING AND AFTERNOON, WHICH LOOKS TO REDUCE SNOW LEVELS FURTHER, AT
LEAST BRIEFLY. ADDITIONAL WINTER WEATHER ADVISORIES WERE ADDED WHERE
CONFIDENCE IN AT LEAST BRIEFLY SLUSHY ACCUMULATIONS IS HIGH ENOUGH.
THE SITUATION IS QUITE FLUID, SO EXPECT FURTHER TWEAKS IN THE
FORECAST THROUGH THE DAY TODAY.
AS FOR THE REST OF THE WEEK INTO THE WEEKEND, THE GREATEST
UNCERTAINTY CONTINUES TO BE THE WEEKEND - ESPECIALLY SUNDAY. EC
PLOTS SHOW WIDESPREAD 0.7 EFI AND HIGHER FOR HIGH TEMPERATURES ON
SUNDAY, WITH A SHIFT OF TAILS OF AT LEAST ZERO. THAT SAID, RECENT
DETERMINISTIC GUIDANCE HAS SIGNIFICANTLY BACKED OFF OF THE
THOUGHT OF WARM TEMPERATURES SUNDAY. ENSEMBLE GUIDANCE IS STILL
REASONABLY WARM SO THERE IS STILL QUITE A FEW DETAILS TO BE WORKED
OUT ON THE EVOLUTION OF THE PATTERN FOR THIS WEEKEND. -AM
AVIATION
05/00Z TAF PERIOD
SHOWERS AND THUNDERSTORMS TRACKING NORTH ACROSS SOUTHWEST MT EARLY
THIS EVENING WILL EVOLVE INTO AN AREA OF STEADY PRECIPITATION
EXTENDING NORTH THROUGH NORTH-CENTRAL MT BY 06Z. THUNDERSTORM
RISK ACROSS SW MT DECREASES AFTER 02Z WITH IFR CONDITIONS
BECOMING WIDESPREAD AT MOST TERMINALS BY 06Z AND PERSISTING
THROUGH MONDAY MORNING. EMBEDDED AREAS OF MODERATE PRECIPITATION
INTENSITY AND POTENTIALLY SOME MIXING WITH WET SNOW EARLY MONDAY
MORNING MAY PUSH CEILINGS TO LIFR AT CENTRAL MT TERMINALS. GUSTY
NORTH WINDS DEVELOP OR PERSIST AT MOST TERMINALS THROUGH MONDAY
WITH GRADUAL IMPROVEMENT EXPECTED MONDAY AFTERNOON. HOENISCH
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED
REGIONAL AVIATION WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 49 32 58 37 / 100 10 10 0
CTB 56 30 60 34 / 50 0 0 0
HLN 47 34 59 37 / 100 30 10 0
BZN 44 30 52 32 / 100 80 10 0
WYS 47 27 57 27 / 70 70 10 0
DLN 43 32 53 33 / 80 60 0 0
HVR 58 31 63 37 / 80 0 0 0
LWT 42 32 51 33 / 100 50 20 10
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR LITTLE BELT AND
HIGHWOOD MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 9 PM MDT THIS EVENING FOR ELKHORN
AND BOULDER MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR BIG BELT,
BRIDGER AND CASTLE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 AM MDT
TUESDAY FOR GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL
MOUNTAINS.
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