712
FXUS65 KTFX 211101
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
401 AM MST SAT DEC 21 2024
KEY MESSAGES
- COOL TEMPERATURES CONTINUE TO BE TRAPPED IN THE MILK RIVER
VALLEY.
- FREEZING RAIN TONIGHT IN THE HAVRE AND HARLEM AREAS.
- ABOVE NORMAL TEMPERATURES EXPECTED ALL OF NEXT WEEK.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL MOVE EASTWARD ACROSS MT
TODAY. HOWEVER, COLD AIR WILL REMAIN TRAPPED AT LOWER LEVELS
AROUND HARLEM/HAVRE. AN UPPER LEVEL DISTURBANCE WILL MOVE EASTWARD
ACROSS THE CWA TONIGHT, AS THE UPPER LEVEL RIDGE MOVES TO OUR
EAST. STRONG DOWNSLOPE WINDS WILL DEVELOP JUST EAST OF THE DIVIDE.
OVERALL WIND SPEEDS ARE EXPECTED TO REMAIN JUST BELOW WARNING
CRITERIA. EXPECT RAIN/SNOW IN THE MOUNTAINS ALONG THE DIVIDE AND
THEN A MIX OF FREEZING RAIN/SNOW IN THE HAVRE/HARLEM AREAS. LIQUID
AMOUNTS UP TO A 0.10 INCHES ARE POSSIBLE IN THE HAVRE/HARLEM
AREAS. WITH COLD AIR TRAPPED NEAR THE SURFACE, FREEZING RAIN IS
EXPECTED IN THIS AREA, THUS A WINTER WEATHER ADVISORY HAS BEEN
ISSUED FOR THE HAVRE/HARLEM AREAS.
THE UPPER LEVEL DISTURBANCE EXITS THE CWA ON SUNDAY MORNING, WITH
THE FORECAST MODELS COMING INTO BETTER AGREEMENT FOR MUCH OF NEXT
WEEK. OVERALL, ABOVE NORMAL TEMPERATURES ARE EXPECTED ALL OF NEXT
WEEK. THE BEST CHANCE FOR ANY PRECIPITATION LOOKS TO BE CHRISTMAS
EVE/CHRISTMAS DAY OVER SOUTHWEST MT. SNOW AMOUNTS ARE FORECAST TO
BE LESS THAN AN INCH AT LOWER ELEVATIONS OF SOUTHWEST MT, WITH 2
TO 5 INCHES POSSIBLE IN THE MOUNTAINS ACROSS ZONE 330. A SECOND
UPPER LEVEL DISTURBANCE WILL MOVE THROUGH THE FAR SOUTHERN
PORTIONS OF THE CWA THU INTO FRIDAY, MAINLY AFFECTING JUST THE
WEST YELLOWSTONE AREA.
- FORECAST CONFIDENCE & SCENARIOS:
THE FORECAST MODELS ARE SHOWING A HIGH POTENTIAL FOR FREEZING RAIN
TONIGHT IN THE HAVRE/HARLEM AREAS, WITH WARM AIR ALOFT AND
TEMPERATURES NEAR/BELOW FREEZING AT THE SURFACE. THIS WILL BE A
QUICK SYSTEM, WITH MOST OF THE THE FREEZING RAIN FALLING IN JUST A
FEW HOURS.
FOR CHRISTMAS EVE/CHRISTMAS DAY, THE PROBABILITY OF 2 INCHES OF
SNOWFALL IS ABOUT 60 PERCENT IN THE MOUNTAINS AROUND BIG SKY/WEST
YELLOWSTONE AREA. FOR THU/FRI...THE WEST YELLOWSTONE AREA HAS
AGAIN ABOUT A 60 PERCENT CHANCE FOR 2 INCHES OR MORE OF SNOWFALL.
BRUSDA
AVIATION
21/06Z TAF PERIOD
GUSTY WINDS ALONG THE ROCKY MOUNTAIN FRONT AND PLAINS WILL
CONTINUE TO DIMINISH TONIGHT WHILE MID- AND HIGHER LEVEL CLOUDS
CONTINUE TO PASS OVERHEAD. RIDGING ALOFT WILL GENERALLY MAINTAIN
VFR CONDITIONS THROUGH 22/00Z; HOWEVER, HI-RES GUIDANCE STILL
HIGHLIGHTS STRATUS/FOG DEVELOPMENT ALONG THE MILK RIVER VALLEY
(KHVR AREA). THE ABUNDANCE OF HIGHER LEVEL CLOUDS IS EXPECTED TO
LIMIT OVERALL COVERAGE/IMPACT AND THIS IS REFLECTED IN THE
IMPACTFUL FOG PROBABILITY BEING LESS THAN 20%. AN APPROACHING
PACIFIC WEATHER SYSTEM THEN BRINGS MOUNTAIN OBSCURING CLOUDS,
LIGHT, MOSTLY MOUNTAIN PRECIPITATION, AND GUSTY WINDS AFTER
22/00Z. - RCG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 55 37 49 32 / 0 20 0 0
CTB 51 35 44 27 / 0 20 0 0
HLN 48 31 45 29 / 0 30 0 0
BZN 49 27 45 25 / 0 30 0 0
WYS 38 16 32 19 / 0 30 20 30
DLN 46 25 42 26 / 0 10 0 0
HVR 38 26 43 23 / 0 80 20 0
LWT 56 33 45 27 / 0 20 0 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM MST SUNDAY
FOR HILL COUNTY-NORTHERN BLAINE COUNTY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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