922
FXUS63 KMQT 222044
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
344 PM EST SUN DEC 22 2024
KEY MESSAGES
- SOUTHERLY WIND LAKE EFFECT SNOW INTO EASTERN UPPER MICHIGAN
WILL BE FOLLOWED BY A CLIPPER SYSTEM MOVING IN FROM THE
WEST. TOGETHER THESE WILL BRING WET SNOW TO SOUTH-CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH MONDAY.
- LAKE EFFECT MAY PRODUCE ANOTHER INCH OR TWO IN LUCE AND SCHOOLCRAFT
COUNTIES BEFORE THE CLIPPER BRINGS ANOTHER 1 TO 3 INCHES.
ISOLATED HIGHER AMOUNTS WILL BE POSSIBLE IN THE LUCE AND
SCHOOLCRAFT COUNTIES. TOGETHER THIS SNOW MAY RESULT IN MINOR
TRAVEL IMPACTS THROUGH MONDAY.
- DRIER AND WARMER CONDITIONS EXPECTED BEHIND THE EARLY WEEK
SYSTEM FOR CHRISTMAS EVE AND CHRISTMAS DAY.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 212 PM EST SUN DEC 22 2024
UPPER MICHIGAN CONTINUES TO BE CAUGHT BETWEEN MID-UPPER LEVEL
TROUGHING ACROSS THE EAST COAST WITH A RIDGE EXTENDING THROUGH THE
NORTHERN PLAINS. WITHIN THIS NORTHWEST FLOW, A WEAK SHORTWAVE
SUPPORTED FLURRIES HERE AND THERE THIS MORNING THANKS TO SOME SEEDER
FEEDER ACTION. FURTHER UPSTREAM, A CLOSED LOW WITH A SHORTWAVE
EXTENDING SOUTH JUST WEST OF THE RIDGE HAS SUPPORTED THE DEVELOPMENT
OF A SURFACE LOW OVER SOUTH DAKOTA, PER RAP ANALYSIS. WITH UPPER
MICHIGAN BEING CAUGHT BETWEEN THE UPSTREAM SURFACE LOW AND A SURFACE
HIGH STRETCHING FROM QUEBEC INTO THE OHIO RIVER VALLEY, IN ADDITION
TO CONTINUED COLD AIR ALOFT AND THE WEAK PROGRESSING SHORTWAVE, A
LONG AXIS LAKE EFFECT SNOW BAND STREAMING NORTHWARD INTO EASTERN
UPPER MICHIGAN HAS BEEN OBSERVED ON GOES SATELLITE PRODUCTS AND KAPX
RADAR. WEBCAMS ALSO SHOW SOME OCCASIONAL LIGHT SNOW IN PARTS OF
SCHOOLCRAFT, LUCE, AND MACKINAC COUNTIES. FROM THESE NOTED
OBSERVATIONS, IMPACTS SO FAR APPEAR TO BE MINIMAL.
SOME CAMS, NAMELY THE RAP AND HRRR HAVE REALLY DIALED BACK THE
INTENSITY OF THESE SNOW SHOWERS INTO EASTERN UPPER MICHIGAN IN THE
PAST 24 HOURS. THIS IS ALSO REFLECTED IN THE RECENT HREF RUN, WHICH
HAS DIALED PROBABILITIES OF SNOWFALL RATES EXCEEDING AN INCH PER HOUR
TO <10%. A GOOD BIT OF THE 06Z AND 12Z DETERMINISTIC GUIDANCE
THOUGH, CONTINUES TO SUGGEST THE POTENTIAL FOR AN INCH OR TWO OF
SNOW IN SCHOOLCRAFT AND LUCE COUNTIES THROUGH MIDNIGHT. HOWEVER, IT
SHOULD BE NOTED THAT MOST OF THESE PACKAGES HAVE LOWERED
ACCUMULATIONS AND HAVE A POOR HANDLE ON THE PLACEMENT OF THE CURRENT
BAND. WITH ALL THIS BEING SAID THOUGH, GENERALLY BELIEVE SNOW
ACCUMULATIONS SHOULD AMOUNT TO AN INCH OR TWO, WITH HIGHER AMOUNTS
BEING POSSIBLE IN A VERY NARROW BAND. CURRENT RADAR TRENDS SUGGESTS
THIS WOULD LIKELY BE FROM NEAR OR EAST OF MANISTIQUE NORTHEASTWARD
INTO LUCE COUNTY NEAR MCMILLAN. ANY SNOW THROUGH THE REMAINDER OF
TODAY AND THROUGH MIDNIGHT WILL ALSO BECOME INCREASINGLY WETTER,
WITH MORNING SNOW RATIOS ESTIMATED NEAR 15:1 TRENDING TOWARD 10:1
THIS EVENING.
THE UPSTREAM CLIPPER LOW WILL CONTINUE ORGANIZING BEFORE SHIFTING
EAST INTO IOWA/SOUTHERN MINNESOTA THIS EVENING. THROUGH MONDAY, THE
LOW WILL TRACK EAST-NORTHEAST THROUGH WISCONSIN, ACROSS LAKE
MICHIGAN, AND THEN INTO LOWER MICHIGAN. THIS WILL POSITION UPPER
MICHIGAN ALONG THE LOW'S NORTHERN FLANK AND UNDER THE INFLUENCE OF
CONTINUED WARM AIR ADVECTION AND A WEAK 850-500MB TROWAL BEFORE THE
LOW'S INVERTED TROUGH AND A WEAK SHORTWAVE SHIFTS THROUGH. THE
EFFECT WILL BE A SWATH OF WET SNOW MOVING THROUGH THE UPPER GREAT
LAKES AFTER MIDNIGHT TONIGHT THROUGH EARLY AFTERNOON MONDAY, WITH
LAKE ENHANCEMENT OF THIS SWATH BEING POSSIBLE INTO EASTERN UPPER
MICHIGAN. A MAJORITY OF GUIDANCE PACKAGES STRETCH THIS SWATH FROM
NEAR IRON MOUNTAIN THROUGH MENOMINEE AND DELTA COUNTIES, INTO
SCHOOLCRAFT COUNTY WHERE LAKE ENHANCEMENT POTENTIAL BEGINS. THIS
SAID THOUGH, THE NORTHERN EXTEND OF THE BAND IS UP FOR SOME DEBATE
THANKS TO THE 12Z NAMNEST AND HRRR KEEPING A MAJORITY OF THIS SOUTH
OF WATSON. DESPITE THESE DIFFERENCES THOUGH, WET SNOW ACCUMULATIONS
SHOULD STILL AMOUNT TO TWO INCHES OR LESS THROUGH THE EVENT UNDER
THIS SWATH. IN SCHOOLCRAFT AND LUCE COUNTIES, LAKE ENHANCEMENT IN THE
MORNING SHOULD END BY AFTERNOON THANKS TO MID-LEVEL WINDS SHIFTING
WITH THE TRANSITING LOW. ADDITIONALLY, SURFACE TEMPS POTENTIALLY
CLIMBING ABOVE FREEZING MONDAY MAKE ANYTHING MORE THAN 3 INCHES
DIFFICULT TO ACHIEVE. CURRENT THINKING IS THAT 2 INCHES COULD BE
WIDESPREAD WITH AMOUNTS POTENTIALLY APPROACHING 4 INCHES BEING
LOCALIZED THROUGH MONDAY EVENING. GIVEN ALL THIS UNCERTAINTY AND
THAT HOLIDAY TRAVEL IS IN FULL SWING, OPTED TO ISSUE AN SPS FOR
LUCE/SCHOOLCRAFT FOR THE TIME BEING. ALL SOLUTIONS KEEP THE WEST
DRY, SAVE FOR SCATTERED SNOW SHOWER POTENTIAL DEVELOPING BY MONDAY
AFTERNOON.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
ISSUED AT 343 PM EST SUN DEC 22 2024
HIGH PRESSURE OVER NORTHERN ONTARIO AND MN AT 1026 MB DESCENDS
SOUTHEAST INTO THE GREAT LAKES MONDAY NIGHT AS A MID LEVEL SHORTWAVE
DROPS SOUTH OVER THE UP EARLY ON. THIS DECREASING CYCLONIC FLOW AND
INCREASING DRY AIR WORKS AGAINST LINGERING LES. AT THE SAME TIME,
WAA INCREASING 850 MB TEMPS CLOSER TO NEGATIVE 1-2C DIMINISHES THE
SUPERIOR SFC-850 MB DELTA-TS GIVEN THAT AVERAGE WATER SFC TEMPS ARE
AROUND 4.5C. ANY SNOWFALL WILL YIELD NEGLIGIBLE ACCUMULATIONS AND NO
IMPACTS. SOME CLOUD COVER LIKELY WILL CONTINUE, BUT DRY WEATHER
SHOULD RETURN TO THE UP BY TUESDAY MORNING. OTHERWISE, UNDER PARTLY
TO MOSTLY CLOUDY SKIES, LOWS SETTLE INTO THE TEENS TO MID 20S. BRIEF
MID LEVEL RIDGING RETURNS FOR THE DAY TUESDAY AS THE SFC HIGH
BECOMES CENTERED OVER SOUTHERN QUEBEC, BUT EXTENDS SOUTHWEST OVER
THE GREAT LAKES BASIN. DRY WEATHER CONTINUES WITH SOME MORE DAYTIME
CLEARING LIKELY, ALLOWING FOR HIGHS TO PEAK BETWEEN 28 TO 33, WARMER
BY THE LAKESHORES.
THE MID LEVEL RIDGE GIVES WAY TO A SHORTWAVE FOR TUESDAY NIGHT INTO
WEDNESDAY AND THE NAM/NHCANDIAN/ECMWF TRY TO SQUEEZE OUT SOME LIGHT
SNOW OUT OF THAT AND SOME ADDITIONAL POSSIBLE LAKE ENHANCEMENT OFF
LAKE MI. THAT SAID, THE SFC HIGH PRESSURE MENTIONED EARLIER REMAINS
PRETTY STAGNANT DURING THIS PERIOD, AND LIFT IS NOT STRONG WITH
SIGNIFICANT DRY LAYERS NOTED ABOVE 900 MB. THUS THE FORECAST
REFLECTS DRY WEATHER PERSISTING UNDER CLOUDY SKIES. OTHERWISE,
EXPECT ANOTHER MILD DAY WITH HIGHS NEAR FREEZING ON TUESDAY WITH
TEMPS THEN FALLING MAINLY INTO THE 20S OVERNIGHT INTO CHRISTMAS DAY.
AFTER CHRISTMAS DAY, ANOTHER RIDGE MOVES OVER THE GREAT LAKES,
CONTINUING THE DRY WEATHER THROUGH THURSDAY. WITH TROUGHING OVER
ROCKIES/PLAINS, SOUTHERLY FLOW BRINGS WELL THAN NORMAL TEMPS (10-20F
ABOVE NORMAL) BY NEXT WEEKEND. ENSEMBLES PROBABILITIES SUPPORT
OVERNIGHT LOWS REMAINING ABOVE FREEZING, ESPECIALLY THE GFS WITH 0%
ACROSS THE UP THURSDAY NIGHT THROUGH THE DAY SUNDAY. THE ECWMF AND
CANADIAN ENSEMBLES SHOW SOMEWHERE BETWEEN 20-40% CHANCES FOR BELOW
FREEZING IN THE INTERIOR FRIDAY NIGHT AND SATURDAY NIGHT. GUIDANCE
SPREADS ON ARRIVAL TIME OF TROUGHS PIVOTING OVER THE GREAT LAKES
LATE NEXT WEEK, BUT THERE IS SUPPORT FOR ANOMALOUS WARMTH AND
MOISTURE SURGING UP FROM THE GULF OF MEXICO OVER THE WEEKEND
ACCOMPANIED BY A SFC LOW. PRIMARY P-TYPE LIKELY WILL BE RAIN GIVEN
THE AIRMASS EXPECTED, BUT THERE ARE LOW CHANCES (15-30%) OF SNOW
MIXING IN RETURN SUNDAY ONWARD. ALSO, DEW POINT TEMPS REACH INTO THE
30S STARTING ON THURSDAY WITH ABOVE FREEZING DEW POINT TEMPS OVER
MUCH OF THE UP FRIDAY NIGHT THROUGH SATURDAY NIGHT. THIS ALONGSIDE
HIGHS IN THE UPPER 30S TO MID 40S WILL HELP MELT SNOWPACK AND ALSO
POSSIBLY RESULT IN SOME PATCHY FOG. WHILE IT'S A WAYS OUT YET, WILL
CONTINUE TO WATCH THE FOG POTENTIAL IN UPCOMING FORECAST PACKAGES AS
THIS COULD HAVE SOME IMPACTS ON HOLIDAY TRAVEL.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1220 PM EST SUN DEC 22 2024
VFR CONDITIONS WILL PREVAIL TODAY BUT CONDITIONS SHOULD DETERIORATE
LATE THIS EVENING AS A CLIPPER SYSTEM PROGRESSES INTO THE UPPER
MIDWEST. THIS WILL RESULT IN MVFR CEILINGS DEVELOPING AT ALL SITES
OVERNIGHT AND CONTINUED GUSTY SOUTHERLY WINDS TO NEAR 25KTS. AS THE
SYSTEM MOVES INTO THE REGION OVERNIGHT AND MONDAY, GRADIENT WILL
RELAX WITH WINDS BECOMING LIGHT. SYSTEM SNOW HAS TRENDED FURTHER
SOUTH THEN PREVIOUS FORECAST PACKAGES, SO SNOW WAS REMOVED FROM KIWD
AND A PROB30 WAS INTRODUCED AT KSAW TO ACCOUNT FOR THIS DECREASING
PROBABILITY.
MARINE
ISSUED AT 343 PM EST SUN DEC 22 2024
SOUTH WINDS OF 20-30 KTS OVER THE EAST AND 15-25 KTS OVER THE WEST
CONTINUE INTO TONIGHT. WINDS FALL BELOW 20 KTS BY AROUND MIDNIGHT IN
THE WEST AND BY MONDAY MORNING IN THE EAST AS A CLIPPER SYSTEM
BEGINS TO MOVE OVER WISCONSIN. THERE IS A LOW CHANCE (15-30%) OF
GALE FORCE GUSTS TO 35 KTS THIS EVENING/EARLY TONIGHT OVER EAST,
MAINLY IN A CORRIDOR BETWEEN MARQUETTE AND GRAND MARAIS NORTHWARD.
AS THE CLIPPER CONTINUES EAST OVER THE GREAT LAKES, WINDS VEER
NORTHERLY MONDAY MORNING, CONTINUING AROUND 20 KTS THROUGH MONDAY
EVENING BEFORE FALLING BACK BELOW 20 KTS FOR MONDAY NIGHT. SOUTHERLY
WINDS, MAINLY 20 KTS OR LESS, ARE EXPECTED TUESDAY THROUGH THE WEEK
AND LIKELY INTO NEXT WEEKEND FOR MOST OF THE LAKE.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...JTP
LONG TERM...JABLONSKI
AVIATION...JTP
MARINE...JABLONSKI
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