213
FXUS63 KMQT 171142
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
642 AM EST TUE DEC 17 2024
KEY MESSAGES
- WESTERLY GALES TO 35 TO 40 KNOTS OVER LAKE SUPERIOR ARE EXPECTED
INTO THIS MORNING. WEST WIND GUSTS UP TO 40 MPH ARE EXPECTED OVER
THE KEWEENAW EARLY THIS MORNING.
- LIGHT LAKE EFFECT SNOW IS POSSIBLE OVER THE WEST TO NORTHWEST
WIND SNOW BELTS TODAY.
- LAKE EFFECT SNOW BEGINS TO PICK BACK UP AGAIN TUESDAY NIGHT
INTO WEDNESDAY OVER THE NORTHWEST WIND SNOW BELTS. GENERALLY
1-3 INCHES OF FLUFFY SNOW IS EXPECTED ALONG LAKE SUPERIOR.
- EYES ARE ON A FAST-HITTING CLIPPER SYSTEM THAT COULD BRING
SOME FLUFFY SNOWFALL OVER THE U.P. THURSDAY AND THURSDAY
NIGHT. HOWEVER, WE MAY MISS OUT ON THE SYSTEM SNOWFALL
ENTIRELY SHOULD IT GO TOO FAR SOUTH. CHANCES TO OF OVER 6"+ OF
SNOWFALL ALONG THE MI/WI STATE LINE HAVE FALLEN TO 10-30%.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 355 AM EST TUE DEC 17 2024
A TIGHT PRESSURE GRADIENT SOUTHWEST OF A SFC LOW NOW OVER JAMES BAY
ALONG WITH COLD ADVECTION IN THE WAKE OF ITS ASSOCIATED COLD FRONT
HAS LED TO GUSTY WEST TO NORTHWEST WINDS ACROSS THE FORECAST AREA
EARLY THIS MORNING, PARTICULARLY ACROSS THE KEWEENAW PENINSULA AND
THE FAR EASTERN SHORELINE OF THE U.P. WHERE GUSTS HAVE REACHED 40
MPH. THE COLD ADVECTION WITH 850 MB TEMPS DROPPING AS LOW AS -8C TO -
9C ARE ALSO JUST COLD ENOUGH TO ALSO GENERATE SOME LIGHT LES
ACROSS THE WEST TO NORTHWEST SNOW BELTS EARLY THIS MORNING.
ALTHOUGH WEST-NORTHWEST WINDS ARE EXPECTED TO GRADUALLY SUBSIDE
THROUGH THE DAY, THE LIGHT LES WILL CONTINUE BUT ONLY A DUSTING
OF SNOW ACCUMULATION IS EXPECTED. HIGHS TODAY UNDER MOSTLY
CLOUDY SKIES WILL BE IN THE UPPER 20S TO LOWER 30S.
WEST-NORTHWEST LAKE EFFECT SNOW WILL RAMP UP LATER TONIGHT AS A
CLIPPER SHORTWAVE TROUGH MOVING THROUGH THE AREA PROVIDES DEEPER
MOISTURE AND MODEST LIFT FOR ENHANCEMENT. THE COMBINATION OF WEAK
LIFT, DEEPER MOISTURE AND CAA WITH 850 MB TEMPS DROPPING TO -12C TO -
13C BY 12Z WED SHOULD LEAD TO 1-2 INCHES OF LES ACCUMULATION TONIGHT
OVER THE WNW SNOW BELTS, GREATEST OVER THE HIGHER TERRAIN OF THE
COPPER COUNTRY, PARTICULARLY FROM IRONWOOD NORTHEAST TO PAINESDALE.
EXPECT LOWS TONIGHT RANGING FROM THE UPPER TEENS TO MID 20S, COOLEST
OVER THE WESTERN INTERIOR AND WARMEST SOUTH CENTRAL AND EAST.
LONG TERM /WEDNESDAY THROUGH MONDAY/
ISSUED AT 419 AM EST TUE DEC 17 2024
A PROGRESSIVE PATTERN CONTINUES OVER THE UPPER GREAT LAKES BEGINNING
WEDNESDAY MORNING AS 500MB TROUGHING SWEEPS OVER THE UP. FOLLOWING
RIDGING WILL BE SHORT-LIVED AS A DIGGING CLIPPER TROUGH RACES
FROM MONTANA TO THE CHICAGO METRO FROM WEDNESDAY NIGHT TO
THURSDAY NIGHT. MORE PROLONGED RIDGING THEN DOMINATES THE
CENTRAL CONUS BEFORE THE NEXT TROUGH IS SET TO ARRIVE OVER THE
GENERAL UPPER MIDWEST REGION TO KICK OFF CHRISTMAS WEEK.
MULTIPLE CHANCES OF SYNOPTIC SNOWFALL ARE POSSIBLE WITH THE
RESULTANT SURFACE FEATURES OF THE AFOREMENTIONED TROUGHS, WITH
THE COLD AIR ALOFT IN THE WAKE OF THOSE TROUGHS PROVIDING LAKE
EFFECT SNOW CHANCES. TEMPERATURES THROUGH THIS PERIOD WILL
PRIMARILY BE BELOW NORMAL FOR THIS TIME PERIOD, AND WITH
MULTIPLE DIFFERENT MECHANISMS FOR SNOWFALL, A "WHITE CHRISTMAS"
REMAINS POSSIBLE, THOUGH A WARMUP IN THE BEGINNING OF CHRISTMAS
WEEK KEEPS THAT SOLUTION SOMEWHAT UNCERTAIN.
AS HAS FREQUENTLY BEEN THE CASE THIS WINTER SO FAR, NORTHWESTERLY
LAKE EFFECT SNOW WILL BE ONGOING WEDNESDAY MORNING. SLIGHTLY
CYCLONIC SURFACE-LAYER FLOW WILL PROVIDE SOME CONVERGENCE TO SUPPORT
THE BANDS, AND THE THERMODYNAMIC SUPPORT IS DEFINITELY PRESENT WITH
850MB TEMPERATURES FALLING TO NEAR -20 C BY 21Z WEDNESDAY PER THE
00Z GFS. THIS CONTRASTED WITH LAKE SUPERIOR TEMPERATURES OF AROUND 6
C WILL PROVIDE GOOD DELTA TS, THOUGH SOUNDINGS SHOW SATURATION NEAR
TO THE TOP OF THE DGZ OR ABOVE WITH SIGNIFICANT DRY AIR AT AND ABOVE
THE INVERSION, SO QPF WILL BE LIMITED. 00Z HREF SHOWS ONLY A 10%
CHANCE OF 1"/HR SNOWFALL RATES IN THESE BANDS, AND WITH 6-HOURLY PMM
SNOWFALL RATES PEAKING AT AROUND 0.1"/6HR, SNOWFALL RATES WILL ONLY
RARELY EXCEED "LIGHT-TO-MODERATE" RANGE. BROADLY EXPECTING AROUND 1-
3 INCHES OF FLUFFY SNOWFALL IN THE ALGER/N. SCHOOLCRAFT/LUCE RANGE
AND IN THE HIGH TERRAIN OF THE WEST HALF WITH LESS THAN AN INCH
EXPECTED ELSEWHERE BY THURSDAY MORNING. WIND GUSTS OF 20-30 MPH
COULD CREATE ISOLATED BLOWING AND DRIFTING SNOW ALONG THE SHORELINES
OF LAKE SUPERIOR, BUT WIDESPREAD TRAVEL IMPACTS ARE NOT EXPECTED.
LES INTENSITY AND COVERAGE WILL WANE OVERNIGHT INTO THURSDAY AS
~1030MB HIGH PRESSURE MOVES NEARLY DIRECTLY OVER LAKE SUPERIOR,
PROVIDING SUPPRESSIVE SUBSIDENCE, THOUGH THERMODYNAMICS ALONE WILL
AT LEAST KEEP VERY LIGHT SNOW SHOWERS OVER THE EAST HALF INTO
THURSDAY MORNING. ATTENTION THEN TURNS UPSTREAM TO A FAST-HITTING
CLIPPER LOW OVER THE DAKOTAS 12Z THURSDAY. ENSEMBLES CONTINUE TO
STRUGGLE TO CONGREGATE ON A TRACK, BUT SOME CONSOLIDATION AROUND THE
LOW BEING OVER IL TO SOUTHERN WI BY FRIDAY 06Z IS SEEN IN THE 00Z
GEFS AND EPS (THOUGH THE EPS IS MAYBE 50 MILES FASTER IN THE TRACK),
THOUGH THE CANADIAN ENSEMBLE STILL HAS A NUMBER OF MEMBERS PASSING
THROUGH THE GREEN BAY TO MILWAUKEE AREA. A CLOSER LOW PASSAGE WOULD
PROVIDE SIGNIFICANT FORCING FOR SNOWFALL WITH ISENTROPIC ASCENT AND
WARM ADVECTION AHEAD OF THE LOW ITSELF ACCOMPANIED BY A DGZ AS DEEP
AS 7KFT BY LATE THURSDAY EVENING PER SOUNDINGS. HOWEVER, WITH
ENSEMBLES SEEMINGLY PREFERRING A SOUTHERLY TRACK, CONFIDENCE IN
SNOWFALL OF SIGNIFICANCE (OR AT LEAST, WINTER STORM WARNING
CRITERIA) IS WANING (10-30%, DOWN FROM NEAR 50% FROM PRIOR
FORECASTS). STILL, COMMUNITIES ESPECIALLY ALONG THE MI/WI STATE
LINE THAT HAVE NOT SEEN MUCH SNOW THIS YEAR (THANKS TO BEING
SHELTERED FROM THE NWERLY LES THAT HAS DOMINATED THUS FAR)
SHOULD CONTINUE TO MONITOR THE FORECAST IN CASE TRENDS REVERSE
FOR THURSDAY THROUGH THURSDAY NIGHT.
WHILE LAKE-850MB DELTA TS REMAIN QUITE SUPPORTIVE OF LES IN THE WAKE
OF THE CLIPPER LOW/PARENT TROUGH, HIGH PRESSURE OF UPPER 1030S TO
LOWER 1040S MB APPROACHES THE UP AREA THROUGHOUT FRIDAY AND THE
WEEKEND, REDUCING CONFIDENCE IN ACCUMULATING SNOWFALL, THOUGH
SOME POPS HAVE BEEN KEPT IN THE FORECAST TO ACCOUNT FOR ENSEMBLE
SPREAD. AS THIS HIGH SHIFTS TOWARDS THE LOWER GREAT LAKES LATE
IN THE WEEKEND TO EARLY MONDAY, ATTENTION TURNS UPSTREAM ONCE
AGAIN TO ANOTHER POTENTIAL CLIPPER LOW, THOUGH ONLY CERTAIN
CLUSTERS WITHIN THE ENSEMBLES SHOW THIS SOLUTION, SO POPS ARE
ONLY AROUND 15-35% TO KICK OFF CHRISTMAS WEEK AT THIS TIME. A
MORE ZONAL PATTERN AROUND THIS TIME HAS THE NBM HIGHS CLIMBING
BACK TOWARDS FREEZING AROUND THIS TIME, WHICH COULD COMPLICATE
THE WHITE CHRISTMAS FORECAST SOMEWHAT, BUT WITH MULTIPLE
MECHANISMS FOR SNOW AND PLENTY OF COOL AIR THIS WEEK (LOWS
FREQUENTLY IN THE SINGLE DIGITS FOR MUCH OF THE INTERIOR UP), IT
MIGHT TAKE A SIGNIFICANT WARM SWING TO CAUSE A SIGNIFICANT
THREAT TO A WHITE CHRISTMAS.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 634 AM EST TUE DEC 17 2024
MVFR CONDITIONS UNDER LIGHT LAKE EFFECT SNOW SHOWERS AT TIMES WILL
BE THE RULE THROUGH THIS EVENING AT THE TERMINALS. LAKE EFFECT
SNOW SHOWERS WILL THEN PICK UP IN INTENSITY LATE TONIGHT OVER
THE NW WIND SNOW BELTS AS CONDITIONS TREND TOWARD IFR,
ESPECIALLY AT IWD AND CMX. MVFR CONDITIONS WILL LIKELY PREVAIL
MOST OF THE TIME AT SAW, ALTHOUGH IT'S POSSIBLE A HEAVIER LAKE
EFFECT SNOW BAND COULD PUSH VISIBILITY NEAR IFR LATE TONIGHT.
OTHERWISE, EXPECT GUSTY WEST WINDS ESPECIALLY THIS MORNING WITH
GUSTS TO 25 KTS POSSIBLE AT IWD AND SAW AND AROUND 35 KTS
POSSIBLE AT CMX.
MARINE
ISSUED AT 419 AM EST TUE DEC 17 2024
ONGOING WESTERLY GALES TO 40 KT WILL WEAKEN IN THE WEST HALF THROUGH
THIS MORNING AND FALL BELOW GALES IN THE EAST BY EARLY AFTERNOON.
WEST-NORTHWEST GUSTS SHARPLY FALL BELOW 20 KT THIS EVENING
THROUGH TONIGHT BEFORE REINVIGORATING TO NORTHWESTERLY GUSTS TO
20-30 KT WEDNESDAY (GALE CHANCES 20% OR LESS). WINDS ONCE AGAIN
FALL BELOW 20 KT IN THE OVERNIGHT PERIOD BEFORE WINDS BEGIN TO
RAMP UP THURSDAY AFTERNOON IN RESPONSE TO A CLIPPER LOW PRESSURE
SYSTEM PASSING SOUTH OF LAKE SUPERIOR. DEPENDING ON HOW CLOSE
THIS SYSTEM PASSES TO THE LAKE, A FEW NORTHEASTERLY GALE FORCE
GUSTS ARE POSSIBLE (20%) IN THE WEST OVERNIGHT THURSDAY, BUT
OTHERWISE, WIND GUSTS CLOSER TO 25 KT ARE MORE LIKELY (~50%). AS
WINDS SWING NORTHWESTERLY, WINDS ONCE AGAIN FALL BELOW 20 KT AS
HIGH PRESSURE DOMINATES THE FORECAST THROUGH THE WEEKEND. THE
WEATHER FOR CHRISTMAS WEEK IS STILL UNCERTAIN, BUT SOME
INDICATIONS OF ANOTHER CLIPPER LOW IN THE MONDAY AFTERNOON-
TUESDAY TIME FRAME PROVIDE CHANCES (~40%) OF WINDS INCREASING
BACK TO 20-30 KT, BUT CONFIDENCE IN THE DETAILS IS LOW AT THIS
TIME.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR
LSZ162-240>244-251-263-264-267.
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ245>250-265-
266.
LAKE MICHIGAN...
NONE.
SHORT TERM...VOSS
LONG TERM...GS
AVIATION...VOSS
MARINE...GS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page