992
FXUS63 KMQT 221913
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
213 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 /TONIGHT THROUGH SATURDAY/
ISSUED AT 255 AM EST SUN DEC 22 2024
UPPER AIR PATTERN CONSISTS OF A 500 MB SHORTWAVE OVER THE NORTHERN
PLAINS 00Z MON WHICH MOVES INTO THE UPPER GREAT LAKES 12Z MON AND
INTO NEW ENGLAND 12Z TUE. ANOTHER TROUGH MOVES INTO THE PLAINS 12Z
TUE AND THIS AFFECTS THE UPPER GREAT LAKES 00Z WED. CLIPPER SYSTEM
TONIGHT WILL PASS MAINLY TO THE SOUTH OF THE AREA WITH THE SOUTHERN
HALF OF THE CWA ON THE NORTHERN FRINGES OF IT AND COMBINED WITH SOME
LAKE ENHANCEMENT FROM LAKE MICHIGAN ACROSS THE EAST. COULD SEE UP TO
3 INCHES ACROSS THE EASTERN CWA OUT OF THIS EVENT. WENT DRY FOR
LATER MONDAY NIGHT INTO TUE NIGHT.
IN THE EXTENDED, THE GFS AND ECMWF SHOW A DEEP UPPER LEVEL TROUGH IN
THE ROCKIES AND A SHORTWAVE OVER THE LOWER ARKANSAS RIVER VALLEY 12Z
WED. THE TROUGH OVER THE ROCKIES EJECTS INTO THE SOUTHERN PLAINS 12Z
THU. DIFFERENCES THEN SHOW UP WITH THIS AS CANADIAN AND ECMWF TAKES
IT EAST NORTHEAST INTO THE OZARK AREA WHILE THE GFS BRINGS IT
FURTHER NORTHEAST INTO THE UPPER MISSISSIPPI VALLEY 12Z FRI. MODELS
GET BACK INTO BETTER AGREEMENT 12Z SAT WITH A DEEP TROUGH IN THE
CENTRAL U.S. THAT STRETCHES ACROSS THE PLAINS WHICH MOVES INTO THE
UPPER GREAT LAKES REGION AND MISSISSIPPI VALLEY 12Z SUN.
TEMPERATURES STAY ABOVE NORMAL FOR THIS FORECAST PERIOD. DID MAKE
SOME ADJUSTMENTS TO POPS AND WENT DRIER INTO THU. NBM WAS WAY TOO
HIGH WITH POPS AS WARM FRONT WAS WELL TO THE SOUTH. WARM FRONT
HEADS NORTH FOR FRIDAY AND DID KEEP SOME POPS IN THU NIGHT ONWARD.
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 255 AM EST SUN DEC 22 2024
SOUTH WINDS GET UP TO 20 TO 30 KNOTS TODAY OUT HEAD OF A CLIPPER
SYSTEM BEFORE DROPPING BELOW 20 KNOTS LATE TONIGHT. THERE COULD BE A
FEW GALE FORCE GUSTS TO 35 KNOTS THIS EVENING ACROSS EASTERN LAKE
SUPERIOR. THE WIND GETS BACK UP TO AROUND 20 KNOTS MON AFTERNOON
FROM THE NORTH BEFORE FALLING BACK BELOW 20 KNOTS BY MONDAY EVENING
WHERE IT STAYS BELOW 20 KNOTS THROUGH THU.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...JTP
LONG TERM...07
AVIATION...JTP
MARINE...07
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