714
FXUS65 KTFX 052015
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
215 PM MDT MON MAY 5 2025
AVIATION SECTION UPDATED.
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.
UPDATE
/ISSUED 902 AM MDT MON MAY 5 2025/
RAIN AND SNOW WILL CONTINUE TO MOVE SOUTHEASTWARD THIS MORNING
ENDING FROM NORTHWEST TO SOUTHEAST THIS AFTERNOON THROUGH THIS
EVENING. LIGHT SNOW IS FALLING ACROSS THE LOWER-ELEVATIONS OF
JUDITH BASIN AND FERGUS COUNTIES. THIS WILL REDUCE VISIBILITY AND
CAUSE SLICK SPOTS ON ROADS THIS MORNING. THE WINTER WEATHER
ADVISORIES WILL REMAIN IN EFFECT AS IS AT THIS TIME. FOR THE
UPDATE, TEMPERATURES ALONG THE MONTANA HIGHWAY 200/US HIGHWAY 87
CORRIDOR WERE DECREASED TO BETTER REFLECT CURRENT OBSERVATIONS AND
TRENDS. MINOR CHANGES WERE MADE TO WIND, WIND GUST, AND SKY
GRIDS. THE REST OF THE FORECAST IS ON TRACK. -IG
DISCUSSION
/ISSUED 902 AM MDT MON MAY 5 2025/
- 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
05/20Z TAF PERIOD
RAIN/SNOW CONTINUE TO AFFECT CENTRAL AND SOUTHWEST MT THIS
AFTERNOON. MODERATE SNOWFALL IS POSSIBLE AT TIMES. THE HEAVIEST
PRECIPITATION SHOULD START TO DIMINISH AFTER 03Z TUE. THE MAIN
CONCERN OVERNIGHT WILL BE THE POTENTIAL FOR FOG. SOME AREAS OVER
NORTH CENTRAL MT COULD GET SOME PERIODS OF DENSE FOG, AS SKIES ARE
PROGGED TO CLEAR OUT THE MOST IN THAT REGION. MOUNTAINS WILL BE
OBSCURED OVER CENTRAL/SOUTHWEST MT THROUGH ABOUT 15Z TUE. BRUSDA
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED
REGIONAL AVIATION WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 51 31 59 38 / 100 10 10 0
CTB 56 28 61 34 / 50 0 0 0
HLN 47 33 60 37 / 100 30 10 0
BZN 44 30 53 31 / 100 80 10 0
WYS 47 27 59 28 / 70 70 10 0
DLN 43 30 53 33 / 90 70 10 0
HVR 58 30 65 36 / 80 0 0 0
LWT 39 29 52 33 / 100 50 20 0
TFX WATCHES/WARNINGS/ADVISORIES
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 UNTIL 6 AM MDT TUESDAY FOR GALLATIN AND
MADISON COUNTY MOUNTAINS AND CENTENNIAL MOUNTAINS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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