447
FXUS65 KTFX 050229
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
829 PM MDT SUN MAY 4 2025
KEY MESSAGES
- ISOLATED THUNDERSTORMS MAINLY BEFORE MIDNIGHT, OTHERWISE
WIDESPREAD LOWER ELEVATION RAIN AND MOUNTAIN SNOW DEVELOP THIS
EVENING.
- RAIN AND SNOW BEGIN TO DIMINISH MONDAY EVENING, BUT WILL LINGER
INTO TUESDAY FOR SOME AREAS OVER OUR FAR EASTERN PORTIONS OF THE
CWA.
- GENERALLY QUIET CONDITIONS EXPECTED FROM WED INTO THE START OF
THE WEEKEND, ALONG WITH A NICE WARMING TREND.
- SOME POTENTIAL FOR ANOTHER WEEKEND WEATHER SYSTEM NEXT WEEKEND,
BUT CONFIDENCE IS QUITE LOW RIGHT NOW FOR THIS OCCURRING.
UPDATE
FOCUS FOR PRECIPITATION THIS EVENING IS SHIFTING FROM A
DECREASING THUNDERSTORM RISK ACROSS SOUTHWEST MT TO AN AREA OF
WIDESPREAD PRECIPITATION DEVELOPING ALONG A BAROCLINIC ZONE
STRETCHING FROM SW TO NE ACROSS THE AREA. HI-RES MODELS APPEAR TO
HAVE A REASONABLE HANDLE ON THE EVOLUTION SO FAR THIS THIS EVENING
WITH HIGHER INTENSITY PRECIPITATION DEVELOPING ALONG AN AXIS OF
700MB FRONTOGENESIS FROM SOUTHERN LEWIS AND CLARK COUNTY NE
THROUGH CASCADE AND CHOUTEAU COUNTIES THROUGH THE EARLY OVERNIGHT
PERIOD. SNOW LEVELS ARE AN AN AREA OF GREATER UNCERTAINTY
OVERNIGHT THROUGH MONDAY MORNING AS COOLING ALOFT HAS BEGUN TO
LOWER SNOW LEVELS SOME ALREADY THIS EVENING WITH ADDITIONAL
COOLING ARRIVING LATER TONIGHT AS COOLER AIR SURGES SOUTH FROM
ALBERTA INTO NORTH-CENTRAL MT. PRECIPITATION INTENSITY IS ALSO
LIKELY TO PLAY A ROLE THROUGH THE OVERNIGHT PERIOD. ACCUMULATING
SNOW STILL LOOKS TO MAINLY BE LIMITED TO ELEVATIONS ABOVE 5000 FT
BUT A MIX OR CHANGE TO WET SNOW IS POSSIBLE AS LOW AS AROUND 3500
FT ACROSS CENTRAL/NORTH-CENTRAL MT BY MONDAY MORNING, OR EARLIER
IN AREAS OF MORE INTENSE PRECIPITATION. HOENISCH
DISCUSSION
/ISSUED 537 PM MDT SUN MAY 4 2025/
- METEOROLOGICAL OVERVIEW:
RAIN IS AFFECTING AREAS MAINLY WEST OF A LINE FROM AUGUSTA TO
SHELBY THIS AFTERNOON, AS AN UPPER LEVEL DISTURBANCE MOVES
NORTHEASTWARD THROUGH THIS AREA. FURTHER SOUTH,
SHOWERS/THUNDERSTORMS ARE DEVELOPING IN LEMHI COUNTY, ID AND IN
BEAVERHEAD COUNTY, MT. THESE STORMS WILL CONTINUE TO MOVE
NORTHEASTWARD THROUGH THIS EVENING. SOME STORMS COULD PRODUCE
BRIEF HEAVY RAINFALL. OVERALL, THIS AREA OF PRECIPITATION OVER THE
SOUTHWEST WILL BECOME A WIDESPREAD AREA OF LOWER ELEVATION RAIN
AND MOUNTAIN SNOW OVER CENTRAL MT THIS EVENING. THE LATEST NAM
CONTINUES TO INCREASE QPF, WITH AREAS AROUND GREAT FALLS FORECAST
TO RECEIVE OVER 1 INCH OF LIQUID. THIS IS REASONABLE, AND SOME
AREAS WILL GET 1 INCH OF RAIN, IT JUST THE HIGHER AMOUNTS MIGHT
NOT BE OVERLY WIDESPREAD. THAT BEING SAID, MANY AREAS OVER
CENTRAL/NORTH CENTRAL MT ARE LIKELY TO GET BETWEEN 0.50 AND 0.75
INCHES OF LIQUID. THE WINTER WEATHER ADVISORY LOOKS ON TRACK FOR
THE KINGS HILL AREA. TEMPERATURES SHOULD COOL THIS EVENING
ALLOWING THE RAIN TO CHANGE TO SNOW. THE GREATEST IMPACTS WILL BE
FOR ELEVATIONS ABOVE 6000 FEET IN THE KINGS HILL AREA.
FOR MONDAY, EXPECT THE PRECIPITATION TO SLOWLY BEGIN TO DIMINISH
FROM WEST TO EAST. THE PRECIPITATION IS LIKELY TO CONTINUE INTO
TUESDAY MORNING THOUGH OVER THE EASTERN PORTIONS OF THE CWA.
TEMPERATURES WILL BE COOL ON MONDAY, THEN REBOUND A BIT FOR
TUESDAY.
FOR WEDNESDAY THROUGH SATURDAY...A NICE WARMING TREND IS EXPECTED
ACROSS THE CWA. AFTERNOON TEMPERATURES ARE LIKELY TO BE IN THE 70S
WHICH IS A GOOD 10 DEGREES ABOVE NORMAL. A ISOLATED
SHOWER/THUNDERSTORM IS POSSIBLE THURSDAY AND AGAIN ON SATURDAY,
BUT CONFIDENCE IS LOW RIGHT NOW FOR THIS ACTIVITY. FOR NEXT
SUNDAY, THE GFS/EC MODELS ARE PROGGING ANOTHER SPRING STORM TO
AFFECT THE CWA. HOWEVER, HOW MUCH PRECIPITATION IT PRODUCES IS
STILL IN QUESTION.
- FORECAST CONFIDENCE & SCENARIOS:
THE MAIN CONCERN IS RAIN/SNOW TONIGHT. THERE IS NOW AROUND A 90
PERCENT CHANCE FOR 0.50 INCHES OF LIQUID AROUND GREAT FALLS
TONIGHT, AND A 60 PERCENT CHANCE OF 0.50 INCHES AROUND HELENA AND
HAVRE. IN TERMS OF SNOW, THERE IS AN 80 PERCENT CHANCE OF SNOW
ACCUMULATIONS AROUND 6 INCHES IN THE KINGS HILL AREA. ALSO THE
MOUNTAINS AROUND PONY COULD GET 4 TO 6 INCHES OF SNOWFALL AS WELL.
WINDS WILL INCREASE ON THURSDAY A BIT, WITH A 60 PERCENT CHANCE OF
WIND GUSTS NEAR 70 MPH ALONG THE FRONT RANGE OF THE ROCKIES AND A
30 PERCENT CHANCE OF WIND GUSTS NEAR 60 MPH NEAR CUT BANK. IT IS
POSSIBLE THAT HIGH WIND STATEMENTS MIGHT BE NEEDED LATER THIS
WEEK. BRUSDA
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 37 51 31 59 / 100 90 10 0
CTB 36 56 30 61 / 90 50 0 0
HLN 40 51 33 59 / 100 90 20 10
BZN 37 46 30 53 / 90 90 50 20
WYS 35 48 28 56 / 50 70 60 20
DLN 37 47 31 53 / 90 80 30 10
HVR 40 59 31 63 / 90 80 0 0
LWT 34 43 31 53 / 90 90 40 20
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL NOON MDT MONDAY FOR LITTLE BELT
AND HIGHWOOD MOUNTAINS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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