651
FXUS65 KGGW 191211 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
511 AM MST THU DEC 19 2024
DISCUSSION
KEY MESSAGES:
- HEADLINES:
COLD WEATHER ADVISORY: 12 PM
- LIGHT SNOW SHOWERS ON FRIDAY, WITH ACCUMULATIONS AS HIGH AS 1
INCH.
- CHRISTMAS DAY SYSTEM MAY PROVIDE A CHANCE AGAIN FOR A WINTRY
MIX.
WEATHER PATTERN OVERVIEW:
THE SHORTWAVE TROUGH MOVING THROUGH NORTH DAKOTA THIS MORNING IS
PRODUCING SNOW BANDS ACROSS NORTHEAST MONTANA. AS WE MOVE INTO MID
AND LATE MORNING, MOST SNOW BANDS ARE EXPECTED TO ADD AN
ADDITIONAL INCH OF SNOWFALL THROUGH NOON. THOUGH WINDS WILL STILL
BE ELEVATED TODAY, A TAPERING OF THE PEAK GUSTS HAS ALREADY
STARTED FOR SOME SITES AND WILL CONTINUE THROUGH LATER THIS
MORNING. GIVEN THIS, BOTH THE WINTER WEATHER ADVISORY AND HIGH
WIND WARNING HAVE BEEN ENDED. WITH RESPECT TO THE COLD ADVISORY,
STILL LOOKING TO BOTTOM OUT IN -30F WIND CHILL RANGE, SO THAT
HEADLINE ALSO REMAINS VALID.
NORTHWEST FLOW ALOFT FROM TODAY WILL ALLOW A WEAK SHORTWAVE TROUGH
TO MOVE THROUGH THE FORECAST PROVIDING LIGHT SNOW SHOWERS FOR
AREAS EAST OF THE UL BEND OF FORT PECK LAKE ON FRIDAY. UP TO
ADDITIONAL INCH OF SNOWFALL IS EXPECTED AT THIS TIME.
THE REGIONS DRYS OUT ON SATURDAY. MEANWHILE OFF THE PNW, A WEAK
TROUGH WILL MOVE OVER THE NW'ERN US, ARRIVING TO THE FORECAST AREA
SUNDAY AM. LATEST ANALYSIS OF THE LOW LEVEL TEMPERATURE CROSS
SECTION OF THE DETERMINISTIC MODELS SHOW A CLEAR WARM NOSE
DEVELOPING YET AGAIN ACROSS NE MT, PROVIDING ADDITIONAL CHANCES
FOR FREEZING RAIN/RAIN MIX. ADDITIONAL MODEL RUNS WILL HELP BETTER
DETERMINE WHAT THE LOW LEVELS TEMPS ARE FORECAST TO MAX OUT AT.
AS THE DISTURBANCE MOVES EAST, MUCH OF THE STATE WILL REMAIN UNDER
RIDGE INFLUENCE, RESULTING IN SURFACE TEMPERATURES CLIMBING UP
ABOVE AVERAGE FOR THIS TIME OF YEAR INTO CHRISTMAS EVE. IN TYPICAL
SANTA FASHION, PRECIPITATION IS LOOKING TO MOVE IN CHRISTMAS DAY,
BUT THERE IS DISAGREEMENT IN THE QPF AMOUNT FOR THAT TIME PERIOD
AND POTENTIALLY YET FOR THE UMPTEENTH TIME, WHAT TYPE OF
HYDROMETEORS WILL FALL. STAY TUNED TO SEE WHAT CHRISTMAS GIFT
WE'LL GET.
FORECAST CONFIDENCE & DEVIATIONS:
MAIN ADJUSTMENTS TO THE NEAR-TERM GRIDS WERE TO POP, BLENDING A
50/50 WEIGHT WITH THE GFS1HR GRIDS, SHOWING A SLOWER DEPARTURE OF
SNOW CHANCES, AS SEEN WITH THE SHALLOW SNOW BANDS NEAR KGGW
BETWEEN 08Z-09Z THIS MORNING.
THE LOWEST ELEMENT OF CONFIDENCE IN THIS FORECAST WAS THE
PRECIPITATION TYPE ON CHRISTMAS DAY. NBM PRODUCED FREEZING RAIN
WEATHER ELEMENTS, BUT FELT IT WAS TOO LOW CONFIDENCE TO KEEP IT IN
THE ZONE FORECAST PRODUCT AND THE WEATHER RADIO. SO I CHANGED IT
TO ONLY SHOW A RAIN/SNOW MIX.
- ENRIQUEZ
AVIATION
UPDATED: 0915Z
FLIGHT CATEGORY: IFR/LIFR BECOMING VFR/MVFR THIS AFTERNOON
DISCUSSION: THE SURFACE LOW CONTINUES TO MOVE FURTHER INTO THE
MIDWEST. WRAP AROUND MOISTURE IS ENDING FROM WEST TO EAST TODAY.
FRIDAY, A CHANCE OF LIGHT SNOW SHOWERS WILL BRING MFVR CONDITIONS
TO MOST TERMINALS.
WINDS: NW WINDS 20-30 KTS GUSTING AS HIGH AS 40 KTS. FROM 18Z TO
06Z FRI, WINDS WILL SWITCH TO BE PRIMARILY SE AT 5-10 KTS.
- ENRIQUEZ
GGW WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL NOON MST TODAY FOR DANIELS-NORTHERN
PHILLIPS-NORTHERN VALLEY-SHERIDAN.
WEATHER.GOV/GLASGOW
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