678
FXUS65 KTFX 252046
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
246 PM MDT SAT APR 25 2026
KEY MESSAGES
- SCATTERED SNOW SHOWER ACTIVITY AND COOL CONDITIONS
CONTINUE THROUGH SUNDAY, WITH THE GREATEST WINTER IMPACTS ALONG
THE NORTHERN ROCKY MOUNTAIN FRONT SUNDAY MORNING.
- TEMPERATURES BEGIN TO SLOWLY TREND CLOSER TO AVERAGE HEADING
INTO THE MIDDLE OF NEXT WEEK; HOWEVER, ADDITIONAL ROUNDS OF
MOSTLY MOUNTAIN SNOW DEVELOP LATE SUNDAY INTO MONDAY AND TO A
LESSER DEGREE AGAIN TUESDAY INTO WEDNESDAY.
- GENERAL MILDER AND DRIER CONDITIONS MOVE IN FOR THE SECOND HALF
OF NEXT WEEK, BUT THERE WILL BE SOME PASSING WEATHER SYSTEMS
WITH AT LEAST BRIEF COOL DOWNS AND INCREASED MOSTLY MOUNTAIN
SNOW NEXT WEEKEND.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
A COLD CORE MID- LEVEL LOW WILL CONTINUE TO CHURN OVER THE
CANADIAN PRAIRIES AND SEND MULTIPLE SHORTWAVES INTO THE NORTHERN
ROCKIES. THIS COMBINED DIURNAL INSTABILITY TO MAINTAIN SCATTERED
TO NUMEROUS SNOW SHOWER ACTIVITY AND WELL BELOW AVERAGE
TEMPERATURES OVER THE NEXT 24 HOURS. LOW LEVEL EASTERLY FLOW LOOKS
TO BRING THE MOST IMPACTFUL ACCUMULATING SNOW IMPACTS TO THE
NORTHERN ROCKY MOUNTAIN FRONT AND ADJACENT FOOTHILL/PLAINS TONIGHT
INTO SUNDAY MORNING.
THIS LOW FINALLY EJECTS NORTHEASTWARD LATER ON SUNDAY, BUT
GENERAL TROUGHING WILL REMAIN IN PLACE THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK. THERE WILL BE SEVERAL SHORTWAVES/SMALLER SCALE
TROUGHS THAT BRING OPPORTUNITIES FOR ROUNDS OF LIGHT, MOSTLY
MOUNTAIN, SNOW AND LOWER ELEVATION INCREASED SHOWER ACTIVITY BY
SUNDAY AFTERNOON. THE DEPARTING CANADIAN LOW WILL TAKE THE COLDER
AIR ALOFT WITH IT, ALLOWING H700 TEMPERATURES TO WARM UP TO AROUND
0 TO -5C AREAWIDE BY MONDAY. THIS WILL COMMENCE A SLOW WARMING
TREND WHILE KEEPING MINOR SNOW IMPACTS MOSTLY IN THE MOUNTAINS.
WHILE A MAJORITY OF ENSEMBLES FAVOR RISING HEIGHTS AND GENERAL
WARMING ALOFT FOR THE SECOND HALF OF NEXT WEEK, THEY ALSO SUPPORT
MORE PACIFIC TROUGHS PASSING THROUGH THE NORTHERN ROCKIES NEXT
WEEKEND. OVERALL, TEMPERATURES LOOK TO RETURN TO NEAR OR SLIGHTLY
ABOVE AVERAGE FOR THE WEDNESDAY THROUGH FRIDAY PERIOD, FOLLOWED BY
COOLER AND WETTER CONDITIONS. SIMILAR TO THE MOST RECENT STORM,
FORCING LOOKS SMALLER SCALE AND TRANSIENT IN NATURE. THIS ERODES
FORECAST CONFIDENCE WITH RAIN, SNOW, AND TEMPERATURES ALL BEING
DETERMINED BY THESE FEATURES. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
SNOW AND SNOW SHOWERS THROUGH SUNDAY MORNING...
SNOW SHOWER ACTIVITY WILL BE MOST NUMEROUS OVER CENTRAL AND
NORTH- CENTRAL MT TONIGHT INTO SUNDAY MORNING. THE LATEST SUITE OF
ENSEMBLE DATA HAVE BECOME MORE AGGRESSIVE WITH LOW LEVEL EASTERLY
FLOW BRINGING A MORE CONCENTRATED AREA OF LIGHT TO MODERATE SNOW
ALONG THE ROCKY MOUNTAIN FRONT AND NEARBY FOOTHILLS AND PLAINS.
THE NBM SNOWFALL EXCEEDENCE PROBABILITY FOR 2 INCHES OF SNOW OR
MORE HAVE INCREASED TO AROUND A 50 TO 60% CHANCE FOR THE E.
GLACIER AND MARIAS PASS AREAS. THE NEARBY HIGHER TERRAIN,
INCLUDING MARIAS PASS HAVE AROUND A 30 TO 40% CHANCE FOR RECEIVING
4 INCHES OF SNOW MORE.
A WINTER WEATHER ADVISORY HAS BEEN ISSUED TONIGHT THROUGH SUNDAY
MORNING TO ADDRESS WINTER DRIVING CONDITIONS, INCLUDING SNOWY
ROADWAYS AND REDUCED VISIBILITY. SOME CONSIDERATION WAS GIVEN TO
ADDING THE EASTERN GLACIER COUNTY AND SOUTHERN ROCKY MOUNTAIN
FRONT ZONES GIVEN THE AFOREMENTIONED EASTERLY UPSLOPE FLOW, BUT
HELD OFF FOR NOW WITH THE HEAVIER AMOUNTS DROPPING OFF SOME
HEADING TO THE EAST AND SOUTHEAST. WHILE SNOW SHOWERS WILL BECOME
MORE WIDESPREAD ACROSS CENTRAL AND NORTH-CENTRAL MT, IMPACTS LOOK
TO BE LIMITED BY SPOTTY SNOWFALL AMOUNTS IN EXCESS OF AN INCH.
MOUNTAIN SNOW SUNDAY NIGHT THROUGH WEDNESDAY...
THE FOCUS THEN SHIFTS TO A SHORTWAVE THAT BRINGS INCREASED MOSTLY
MOUNTAIN SNOW TO CENTRAL AND SOUTHWEST MT SUNDAY NIGHT INTO
MONDAY. WARMING TEMPERATURES ALOFT LOOK TO KEEP THE ACCUMULATING
SNOW THREAT OVER THE HIGHER TERRAIN. NBM PROBABILISTIC GUIDANCE
RESERVES THE HIGHEST CHANCES (60 TO 70%) FOR SNOWFALL AMOUNTS OVER
2 INCHES FOR AREAS ABOVE 6,000 FT, MOSTLY OVER THE LITTLE BELTS
AND THE MOUNTAIN PEAKS OF BEAVERHEAD, GALLATIN, AMD MADISON
COUNTIES. THE PRIMARY UNCERTAINTY WITH THIS SYSTEM IS DURING THE
ONSET WHEN WARM AIR ADVECTION ALOFT IS CAPABLE OF PRODUCING A
BRIEF PERIOD OF HEAVIER BANDING ON THE NORTHERN FRINGE OF THE
SNOW. THE WINDOW OF OPPORTUNITY TO PRODUCE HEAVIER SNOW DOESN'T
APPEAR TO BE LONG ENOUGH TO EXERT IMPACTFUL CONDITIONS, BUT THIS
SITUATION WILL BE MONITORED FOR THE NEED OF WINTER ADVISORIES.
PASSING SHORTWAVES BRING ADDITIONAL ROUNDS OF LIGHT, MOSTLY
MOUNTAIN, SNOW THROUGH WEDNESDAY, THOUGH FURTHER WARMING ALOFT
SHOULD PRECLUDE WIDESPREAD IMPACTS. - RCG
AVIATION
25/18Z TAF PERIOD
AREA REMAINS BENEATH A MOIST AND SOMEWHAT UNSTABLE CYCLONIC
NORTHWEST FLOW ALOFT THROUGH THE TAF PERIOD. THIS WILL MAINTAIN
LOWER VFR TO MVFR CLOUD CEILINGS AND MOUNTAIN OBSCURATION WITH
PERIODS OF INCREASED SNOW SHOWER ACTIVITY. SCATTERED SHOWERS THIS
AFTERNOON WILL BRING THE RISK OF BRIEF MVFR CONDITIONS TO MOST
TERMINALS WITH A PERIOD OF MORE WIDESPREAD SNOW SHOWERS AND
ASSOCIATED MVFR CONDITIONS DEVELOPING THIS AFTERNOON NEAR THE
ROCKY MTN FRONT AND KCTB TERMINAL, POTENTIALLY EXPANDING TO
PORTIONS OF SOUTHWEST MT TONIGHT THROUGH SUNDAY MORNING. HOENISCH
PRELIMINARY POINT TEMPS/POPS
GTF 24 39 22 48 / 50 50 30 30
CTB 19 35 15 47 / 70 80 10 10
HLN 23 42 25 47 / 30 40 30 50
BZN 22 44 25 47 / 20 30 60 70
WYS 17 44 21 43 / 30 60 70 80
DLN 23 47 27 48 / 10 20 50 50
HVR 20 41 20 49 / 40 20 10 10
LWT 20 37 22 43 / 30 50 50 50
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON MDT
SUNDAY FOR EAST GLACIER PARK REGION-NORTHERN HIGH PLAINS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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