910
FXUS65 KGGW 212013
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
113 PM MST SAT DEC 21 2024
DISCUSSION
KEY MESSAGES:
- FREEZING RAIN EXPECTED LATE TONIGHT THROUGH SUNDAY AFTERNOON.
A WINTER WEATHER ADVISORY HAS BEEN ISSUED.
- STRETCH OF ABOVE NORMAL TEMPERATURES CONTINUES FOR SEVERAL
DAYS THROUGH THE CHRISTMAS HOLIDAY.
WEATHER PATTERN OVERVIEW:
A WARM UPPER RIDGE WILL BE THE MAIN WEATHER PLAYER THROUGH EARLY
NEXT WEEK MAKING FOR WARM TEMPERATURES (ESPECIALLY JUST OFF THE
SURFACE). THIS TEMPERATURE PROFILE, COLDER SUB FREEZING TEMPS AT
THE SURFACE WITH WARM TEMPS ALOFT (CLOSE TO 50F AT 2K FEET AGL)
WILL SET THE STAGE FOR A FREEZING RAIN EVENT STARTING IN THE WEST
AROUND 09Z TONIGHT AS A DISTURBANCE PASSES THROUGH THE UPPER
RIDGE. CURRENT WINTER WEATHER ADVISORY LOOKS ON TRACK, WITH THE
THREAT FOR FZRA TAPERING AS TEMPS WARM ABOVE FREEZING IN THE
AFTERNOON.
THE PRECIPITATION PUSHES OFF TO THE EAST SUNDAY EVENING AS THE
DISTURBANCE EXITS. HIGH PRESSURE RIDGING WILL RETURN, RESULTING
IN A WARM AND DRY DAY ON MONDAY. TEMPERATURES WILL REMAIN ABOVE
NORMAL ALL WEEK. THE UPPER RIDGE FLATTENS SOMEWHAT ON CHRISTMAS
DAY WITH ANOTHER DISTURBANCE PUSHING THROUGH, HOWEVER WITH THIS
DISTURBANCE MOST OF THE ENERGY STAYS WELL TO THE SOUTH. A WARM SW
FLOW ALOFT IS EXPECTED THURSDAY AND FRIDAY.
FORECAST CONFIDENCE & DEVIATIONS:
CONFIDENCE IS HIGH ON THE FREEZING RAIN MAINLY NORTH OF THE
MISSOURI RIVER AND ALONG THE LOWER YELLOWSTONE VALLEY EARLY
SUNDAY MORNING AND AFTERNOON. CONFIDENCE IS HIGH ON ABOVE NORMAL
TEMPS FOR THE NEXT SEVERAL DAYS. STAYED WITH HIGHER POPS THAN THE
BASE FORECAST ON SUNDAY.
AVIATION
UPDATED: 18Z
FLIGHT CATEGORY: VFR BECOMING MVFR TO LIFR IN HAZARDOUS FREEZING
RAIN AND POTENTIALLY FOG EARLY SUNDAY MORNING. CONDITIONS WILL
IMPROVE STARTING SUNDAY AFTERNOON.
DISCUSSION: THERE WILL BE SOME MID AND HIGH CLOUDS AT TIMES IN
OTHERWISE CLEAR SKIES THIS EVENING. THE CLOUD DECK WILL LOWER TO
MVFR OR EVEN IFR AT TIMES AFTER MIDNIGHT, WITH FREEZING RAIN
POSSIBLE AFTER 10Z SUNDAY AT KGGW AND AFTER 12Z SUNDAY AT THE
OTHER TAF SITES.
WINDS: EXPECT GENERALLY LIGHT AND VARIABLE WINDS.
LLWS: WITH THE APPROACHING WEATHER DISTURBANCE TONIGHT EXPECT
SOME PERIODS OF LOW LEVEL WIND SHEAR AT 2K FT AGL WHERE WESTERLY
WINDS WILL BLOW AT 35-40KTS.
GGW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 2 AM TO 11 AM MST SUNDAY FOR
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
NORTHERN PHILLIPS-NORTHERN VALLEY.
WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM MST SUNDAY FOR DANIELS-
DAWSON-EASTERN ROOSEVELT-MCCONE-RICHLAND-SHERIDAN-WESTERN
ROOSEVELT-WIBAUX.
WEATHER.GOV/GLASGOW
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