081
FXUS65 KTFX 191108
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
408 AM MST THU DEC 19 2024
AVIATION SECTION UPDATED.
KEY MESSAGES
- UPPER LEVEL RIDGING BUILDS IN TODAY, BRINGING A PERIOD OF MUCH
CALMER WEATHER TO THE AREA
- BREEZY ON FRIDAY AS A WEAK SYSTEM MOVES THROUGH
- ACTIVE SOUTHWESTERLY FLOW SETS UP OVER THE WEEKEND AND THROUGH
MOST OF NEXT WEEK, KEEPING OUR WEATHER WARM AND ACTIVE
DISCUSSION
/ISSUED 323 AM MST THU DEC 19 2024/
METEOROLOGICAL OVERVIEW:
BEHIND THE UPPER LEVEL TROUGH THAT TROUGH STRONG WINDS AND SOME
SNOW TO THE AREA ON WEDNESDAY, UPPER LEVEL RIDGING WILL BRIEFLY
SET UP ACROSS THE AREA TODAY, WHICH WILL RESULT IN QUIET AND
GENERALLY WARM WEATHER ACROSS NORTH CENTRAL AND SOUTHWESTERN
MONTANA, THOUGH A SURFACE COLD FRONT DRAPED ALONG A LINE FROM CUT
BANK TO FORT BENTON TO GRASS RANGE WILL KEEP AREAS TO ITS NORTH
AND EAST ON THE COOLER SIDE, WITH SOME AREAS IN THE CORE OF THE
COLDER AIR ONLY REACHING THE TEENS WHILE MOST OF THE REST OF US
REACH INTO THE 40S.
WHILE THE UPPER LEVEL RIDGE WILL MORE OR LESS MAINTAIN ITS
INFLUENCE OVER THE WEATHER THROUGH SATURDAY, A FEW WEAK WAVES OF
ENERGY WILL RIDE OVER THE RIDGE, BRINGING A FEW PERIODS OF
SLIGHTLY ACTIVE WEATHER TO THE AREA. THE FIRST SUCH PERIOD WILL BE
ON FRIDAY, AS A WEAK AND FAST MOVING SYSTEM RESULTS IN SOME
BREEZY WINDS ACROSS THE USUALLY WINDIER SPOTS ALONG THE ROCKY
MOUNTAIN FRONT AND ALONG THE NORTHERN SLOPES OF THE LITTLE BELT
MOUNTAINS. SATURDAY WILL BE QUIET, FOLLOWED BY THE ARRIVAL OF A
SLIGHTLY MORE VIGOROUS SYSTEM PUSHES THROUGH SATURDAY NIGHT AND
SUNDAY, BRINGING SOME LIGHT RAIN AND MOUNTAIN SNOW TO CENTRAL AND
SOUTHWESTERN MONTANA. BEHIND THIS SYSTEM, MULTIPLE WEAK
DISTURBANCES WILL MOVE THROUGH THE AREA NEXT WEEK EMBEDDED IN
WESTERLY FLOW, WHICH WILL BRING MULTIPLE CHANCES FOR LIGHT TO
MODERATE SNOW TO AREAS IN SOUTHWESTERN MONTANA AND ALONG THE
CONTINENTAL DIVIDE WHILE THE PLAINS REMAIN ON THE WARM BUT BREEZY
SIDE.
FORECAST CONFIDENCE & SCENARIOS:
THROUGH THE REST OF THE WEEK, CONFIDENCE IN THE FORECAST IS
FAIRLY HIGH, WITH THE TWO MAIN AREAS OF UNCERTAINTY BEING HOW FAR
NORTH AND EAST THE WARM AIR MAKES IT TODAY ACROSS THE PLAINS AND
IF SOME SNOW WILL ACCOMPANY A WARM FRONT THAT WILL PUSH THROUGH
FRIDAY MORNING. FOR THE FORMER, I WOULD EXPECT THE COLD AIR WILL
BE FAIRLY STUBBORN, BUT IT SHOULD AT LEAST MAKE IT THROUGH CUT
BANK, GREAT FALLS, AND LEWISTOWN BY THIS AFTERNOON BEFORE THE COLD
AIR STOPS ITS PROGRESS. FOR THE LATTER, MODELS SEEM TO BE LESS
ENTHUSIASTIC ABOUT THE PROSPECT OF SNOW DEVELOPING WEST OF A
HARLEM TO GRASS RANGE THAN THEY WERE EARLIER, GOING FROM AROUND A
20% CHANCE TO ABOUT A 10% CHANCE. EVEN IF THE SNOW WERE ABLE TO
DEVELOP, IT WOULD GENERALLY BE LIGHT AND NOT CAUSE MUCH IN THE WAY
OF IMPACTS TO DAY TO DAY LIFE.
BEYOND SATURDAY, WHILE MODELS DO DIVERGE ON THE DETAILS, THE
OVERALL MESSAGE IS FAIRLY CONSISTENT, WITH SOUTHWESTERLY FLOW
DEVELOPING WITH MULTIPLE WAVES EMBEDDED IN THE FLOW. RIGHT NOW,
THE MAIN SOURCE OF DISAGREEMENT IN THE MODELS APPEARS TO BE WHERE
THE STRONGEST FLOW AND MOISTURE TRANSPORT SET UP OVER THE PACIFIC
AND WEST COAST. WHILE THIS WON’T AFFECT OUR FORECAST MUCH, WE WILL
HAVE TO PAY ATTENTION TO THESE NUANCES FOR THE POTENTIAL FOR
IMPACTFUL SNOW ALONG THE CONTINENTAL DIVIDE AND SOUTHWESTERN
MONTANA, AS WELL AS WINDS ACROSS THE PLAINS DEPENDING ON THE EXACT
LOCATION OF ANY ASSOCIATED JET STREAKS. SO WHILE THE DETAILS WILL
REMAIN UNCERTAIN FOR THE NEXT FEW DAYS, THE MAIN MESSAGE WILL
GENERALLY REMAIN THAT A PERIOD OF MORE ACTIVE WEATHER IS EXPECTED
FOR CHRISTMAS WEEK. LUDWIG
AVIATION
19/12Z TAF PERIOD
EXPECT VFR CONDITIONS ACROSS NORTH CENTRAL AND SOUTHWESTERN
MONTANA OVER THE NEXT 24 HOURS AS UPPER LEVEL RIDGING MOVES IN.
THERE IS A LOW RISK OF SOME MID/LOW LEVEL CLOUDS AT HAVRE AS
WARMER AIR RUNS OVER SOME COLDER AIR AT THE SURFACE, BUT THERE
ISN'T ENOUGH CONFIDENCE IN THIS TO PUT IN THE TAF AT THIS TIME.
LUDWIG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 46 30 55 34 / 0 0 0 0
CTB 39 23 49 29 / 0 10 0 0
HLN 44 27 48 28 / 0 0 0 0
BZN 42 22 47 24 / 0 0 0 0
WYS 32 9 37 8 / 0 0 0 0
DLN 41 24 45 25 / 0 0 0 0
HVR 20 8 38 19 / 0 10 0 0
LWT 42 25 52 31 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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