726
FXUS63 KMQT 181729
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1229 PM EST WED DEC 18 2024
KEY MESSAGES
- WINTER WEATHER ADVISORIES ARE IN EFFECT FOR PORTIONS OF THE
WESTERN AND EASTERN UP FOR LAKE EFFECT SNOW IN THE NORTHWEST
WIND SNOW BANDS INTO TONIGHT.
- EYES ARE ON A FAST-HITTING CLIPPER SYSTEM THAT COULD BRING
SOME FLUFFY LAKE ENHANCED SNOWFALL OVER PORTIONS OF THE U.P.
LATE THURSDAY INTO THURSDAY NIGHT.
- ANOTHER SYSTEM COULD POTENTIALLY BRING A FEW INCHES OF SNOW
ON MONDAY WITH LIKELY DRIER AND WARMER CONDITIONS BEHIND THE
SYSTEM FOR CHRISTMAS EVE INTO CHRISTMAS DAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 325 AM EST WED DEC 18 2024
WITH THE SURFACE COLD FRONT NOW PAST THE UP, SNOW WILL CONTINUE TO
BUILD IN THE NORTHWEST WIND LES BANDS. WITH EVEN THE 5TH PERCENTILE
OF THE NBM SHOWING OVER 20:1 SNOW RATIOS BY THIS EVENING, THE SNOW
FALLING TODAY AND TONIGHT WILL BE QUITE FLUFFY. MEAN HREF QPF
THROUGH 12Z THURSDAY IS AROUND A QUARTER TO A THIRD OF AN INCH,
LEADING TO 1-3 INCHES OF SNOWFALL EXPECTED WIDESPREAD ALONG LAKE
SUPERIOR WITH AREAS OF 3-5 INCHES IN ALGER, LUCE, AND N. SCHOOLCRAFT
COUNTIES AS WELL AS THE TERRAIN OF THE WEST HALF. SNOWFALL WILL END
IN THE WEST SOONER THAN THE EAST AS HIGH PRESSURE OF A GEFS-MEAN
1032 MB ENCROACHES ON THE REGION, WITH THE GEFS SHOWING THE CENTER
OVER NORTHWESTERN ONTARIO BY 06Z THURSDAY. THE SURFACE WIND PATTERN
DRIVING LAKE EFFECT SNOW BANDS WILL BE FURTHER COMPLICATED OVERNIGHT
TONIGHT BY A CLEAR LAND BREEZE SHOWN IN THE CAMS. ULTIMATELY, THIS
FORECAST PACKAGE WILL MAINTAIN THE CURRENT WINTER WEATHER ADVISORIES
THROUGH 00Z THURSDAY FOR GOGEBIC, ONTONAGON, AND N. HOUGHTON
COUNTIES WITH ADVISORIES CONTINUING THROUGH 06Z THURSDAY FOR ALGER,
LUCE, AND N. SCHOOLCRAFT COUNTIES. WITH SNOWFALL RATES DECREASING
THROUGH THE AFTERNOON IN THE WEST, A CANCELLATION MAY (30%
CHANCE) COME AS SOON AS 18Z, WHILE ~30% PROBABILITIES OF
6-HOURLY SNOWFALL RATES OF 2"/6- HR IN THE EAST HALF OF ALGER
COUNTY LINGER UNTIL AROUND 12Z, WHICH COULD JUSTIFY AN
EXTENSION. HOWEVER, UNCERTAINTY IN THE EVOLUTION OF SAID TIMING
CHANGES WILL LEAVE THE DECISION TO CHANGE HEADLINES TO BE MORE
REACTIVE THAN PROACTIVE. WIND GUSTS OF UP TO 30 MPH IN THE EAST
IN ADDITION TO FALLING FLUFFY SNOW WILL CREATE SOME PATCHY
BLOWING AND DRIFTING SNOW THREATS ALONG LAKE SUPERIOR IN THE
EAST TODAY. ATTENTION THEN TURNS UPSTREAM TO AN APPROACHING
CLIPPER LOW AND ASSOCIATED ISENTROPIC ASCENT AND WARM ADVECTION,
THOUGH EVEN THE 75TH TO 90TH PERCENTILE OF AVAILABLE GUIDANCE
ONLY BRINGS CHANCES OF PRECIPITATION PRIOR TO 12Z THURSDAY IN
THE IRONWOOD AREA OF ONLY AROUND 20%. IT WILL BE A PRETTY COOL
OVERNIGHT PERIOD, WITH WIDESPREAD 70-90% CHANCES OF SINGLE-DIGIT
LOWS IN THE WEST HALF PER THE NBM, WITH THE DETERMINISTIC NBM
SHOWING VALUES NEAR 0 FOR THE WESTERN MARQUETTE/SOUTHERN
BARAGA/NORTHERN IRON COUNTY REGION. THE APPROACHING HIGH
PRESSURE CALMING THE WINDS WILL AT LEAST HELP WIND CHILLS ONLY
BE SLIGHTLY BELOW 0 OVERNIGHT.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 451 AM EST WED DEC 18 2024
BEGINNING THURSDAY, STILL SOME MODEL UNCERTAINTY REGARDING THE TRACK
OF THE WEAKENING CLIPPER SYSTEM DIVING SE THROUGH THE NORTHERN
PLAINS AND MIDWEST ON THURSDAY. GENERALLY PRETTY GOOD AGREEMENT
BETWEEN MOST OF THE 00Z OPERATIONAL RUNS AND CLUSTERING OF GEFS AND
EPS ENSEMBLE MEMBERS AND MEANS WHICH SHOWS A CONSENSUS TRACK TAKING
THE LOW THROUGH THE DAKOTAS AND IA REACHING NORTHERN IL BY THU
EVENING. THE NOTABLE EXCEPTION AND OUTLIER TO THIS CONSENSUS TRACK
IS THE LATEST 00Z NAM WHICH HAS TRENDED MUCH FARTHER NORTH WITH THE
LOW TAKING IT THROUGH ND, CENTRAL MN AND CENTRAL WI. THE NAM
SOLUTION IS ALSO SUSPICIOUS IN THAT SAMPLING OF THE SYSTEM'S
SHORTWAVE FOR THE 00Z RUN WAS STILL WELL OFFSHORE OVER THE NORTHERN
PACIFIC, WHERE THE NAM'S INSUFFICIENT SAMPLING OVER MARINE AREAS HAS
HISTORICALLY LED TO POOR RESULTS. SIDING WITH THE MORE CONSISTENT
GFS, ECMWF AND GEFS/EPS MEAN SOLUTIONS, MOST OF THE MODERATE TO
POTENTIALLY HEAVIER SYSTEM SNOW WITH THE CLIPPER SHOULD STAY SOUTH
INTO CENTRAL AND SOUTHERN WI ON THURSDAY WHERE THOSE MODELS INDICATE
THE BETTER ISENTROPIC ASCENT WILL BE LOCATED JUST NORTH OF THE
SYSTEM'S 850 MB WARM FRONT. HOWEVER, IT LOOKS LIKE THERE WILL BE
ENOUGH WEAK FORCING ON THE NORTHERN PERIPHERY OF THE SYSTEM TO
GENERATE A DOMINANT N-S LAKE ENHANCED SNOW BAND OFF LAKE MI WHICH
MODELS, PARTICULARLY THE HIGH-RES NSSL-WRF AND HRRR, SHOW COULD
POTENTIALLY IMPACT DELTA, MENOMINEE, SCHOOLCRAFT, ALGER AND EASTERN
MARQUETTE COUNTIES THURSDAY AFTERNOON INTO THURSDAY NIGHT WITH
MODERATE TO POSSIBLY HEAVY LAKE EFFECT SNOW UNDER A DEVELOPING
CONVERGENT S-SE SFC-850 MB WIND FLOW AND 850 MB TEMPS HOVERING AT -
12C TO -14C. A FEW OF THE MODELS EVEN SUGGEST A LAKE ENHANCED BAND
FORMING OVER CENTRAL LAKE SUPERIOR AND THEN MOVING INTO AND
IMPACTING THE KEWEENAW PENINSULA WITH MODERATE TO OCCASIONALLY HEAVY
LES SNOW LATE THURSDAY INTO THURSDAY NIGHT. WINTER WEATHER ADVISORY
HEADLINES WILL LIKELY NEED TO BE CONSIDERED AT SOME POINT FOR THESE
COUNTIES THU-THU NIGHT BUT GIVEN THAT THERE STILL IS SOME MODEL
UNCERTAINTY WITH THE FORECAST DETAILS AND ONGOING HEADLINES IN
EFFECT TODAY WILL HOLD OFF ON ADDITIONAL HEADLINES FOR NOW.
AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE NORTHERN PLAINS FRIDAY
AND BACKING N-NE SFC-850 WIND FLOW BECOMES MORE ANTICYCLONIC THROUGH
THE DAY, EXPECT THE ASSOCIATED INCOMING SUBSIDENCE TO GREATLY
DIMINISH THE LES ACROSS THE AREA THROUGH THE DAY. HOWEVER, REMNANT
LAKE-INDUCED TROUGHING OVER THE GREAT LAKES BASIN MAY BE JUST STRONG
ENOUGH TO ALLOW WEAK LAKE EFFECT SNOWFALL TO CONTINUE OVER THE N-NW
WIND SNOW BELTS FRIDAY NIGHT INTO SATURDAY AS THE THERMODYNAMIC
PROFILE (LAKE DELTA-TS INCREASING TO THE LOWER TO MID 20S C) WILL BE
VERY SUPPORTIVE OF LAKE EFFECT SNOW DESPITE THE RIDGING PUSHING INTO
THE AREA. THE LAKE EFFECT SNOW LOOKS TO EVENTUALLY END LATER THIS
WEEKEND (SATURDAY NIGHT INTO SUNDAY) AS THE HIGH PRESSURE RIDGING
FROM ONTARIO FINALLY FIGHTS ITS WAY INTO THE GREAT LAKES BASIN.
EXPECT A GENERAL WARMING TREND FOR CHRISTMAS WEEK AS WARM AIR FROM
MORE TROPICAL AREAS OF THE PACIFIC MOVES OVER THE ROCKIES AND
DOWNSLOPES INTO THE CANADIAN AND U.S. PLAINS. THAT BEING SAID, IT
DOES LOOK LIKE WE WILL HOLD ON TO COOLER TEMPERATURES A LITTLE
LONGER EARLY NEXT WEEK, ENOUGH TO ALLOW ANOTHER WARM ADVECTION
SNOWFALL EVENT TO POTENTIALLY OCCUR ON MONDAY AS A WAVE MOVING OVER
THE NORTHERN ROCKIES IS FORECAST TO TRACK THROUGH THE NORTHERN
PLAINS INTO THE WESTERN GREAT LAKES. MODELS SHOWING REMARKABLY GOOD
AGREEMENT ON THE TRACK OF THIS SYSTEM FIVE DAYS OUT, AND IF MODEL
CONSISTENCY CONTINUES TO HOLD OVER THE NEXT SEVERAL MODEL RUNS
FORECAST CONFIDENCE WILL INCREASE ON THE POTENTIAL FOR A WIDESPREAD
FEW INCHES OF SNOW ACROSS THE U.P. ON MONDAY, INCREASING CHANCES FOR
A WHITE CHRISTMAS OVER MUCH OF THE AREA. AFTER MONDAY'S SYSTEM
WEAKENS AND MOVES EAST, MODELS INDICATE DRIER AND WARMER CONDITIONS
FOR CHRISTMAS EVE INTO CHRISTMAS DAY AS WEAK RIDGING MOVES OVER THE
AREA AND HIGH TEMPS POSSIBLY REACH AT OR ABOVE FREEZING BOTH DAYS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1229 PM EST WED DEC 18 2024
LAKE EFFECT SNOW SHOWERS AND CLOUD COVER WILL CONTINUE IN THIS
PERIOD, BRINGING WITH IT TAPERING SNOW SHOWERS THIS AFTERNOON,
PRIMARILY MVFR CONDITIONS AT KCMX/KIWD/KSAW, AND GUSTY NORTHWEST
WINDS UP TO 25KTS THIS AFTERNOON. IMPROVEMENT TO VFR IS EXPECTED
THIS EVENING AT KSAW AND OVERNIGHT AT KIWD. THURSDAY, A SYSTEM
MOVING THROUGH THE UPPER MIDWEST WILL RESULT IN INCREASED SNOW
CHANCES THROUGH THE DAY AND A TREND TOWARD MVFR CEILINGS AND
IFR/LIFR VISIBILITIES.
MARINE
ISSUED AT 451 AM EST WED DEC 18 2024
EXPECT NORTHWEST WINDS OF 20 TO 30 KNOTS OVER THE LAKE TODAY,
HIGHEST EAST HALF. SOME MODERATE FREEZING SPRAY WILL LIKELY DEVELOP
OVER CENTRAL AND EASTERN LAKE SUPERIOR AS COLDER AIR DROPS DOWN FROM
CANADA. THE FREEZING SPRAY ENDS WEDNESDAY NIGHT AS WINDS WEAKEN TO
20 KNOTS OR LESS AGAIN DUE TO A HIGH PRESSURE RIDGE MOVING THROUGH
THE UPPER GREAT LAKES. AS A CLIPPER DROPS DOWN TOWARDS THE CHICAGO
AREA WEDNESDAY NIGHT AND THURSDAY, SECONDARY INVERTED SHORTWAVE
TROUGHS OVER NORTHERN LAKE MICHIGAN AND SOUTHERN LAKE SUPERIOR
ASSOCIATED WITH THE CLIPPER MAY BE STRONG ENOUGH TO CREATE NORTHEAST
TO NORTHERLY WINDS OF 20 TO 25 KNOTS OVER WESTERN LAKE SUPERIOR
THURSDAY NIGHT BEFORE WEAKENING AGAIN BY FRIDAY MORNING. A SURGE OF
ARCTIC AIR ACROSS THE LAKE COULD CAUSE N-NW WINDS TO INCREASE TO 25
KNOTS AGAIN LATE FRIDAY INTO FRIDAY NIGHT AT LEAST OVER THE EAST
HALF OF THE LAKE BEFORE HIGH PRESSURE FIGHTS ITS WAY INTO THE GREAT
LAKES BASIN AND WINDS DIE BACK DOWN AGAIN BLO 20 KTS FOR THE WEEKEND.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING
FOR MIZ002-003-009.
WINTER WEATHER ADVISORY UNTIL 1 AM EST THURSDAY FOR MIZ006-007-
085.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...GS
LONG TERM...VOSS
AVIATION...JTP
MARINE...VOSS
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