400
FXUS63 KMQT 212059
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
359 PM EST SAT DEC 21 2024
KEY MESSAGES
- LAKE EFFECT SNOW STREAMING INTO MARQUETTE AND ALGER COUNTIES
WILL TAPER OFF THIS AFTERNOON AND EVENING. UNTIL THEN, SOME
ISOLATED HAZARDOUS DRIVING CONDITIONS WILL BE POSSIBLE DUE TO
QUICKLY CHANGING VISIBILITIES AND LIGHT SNOW ACCUMULATIONS ON
SOME ROADWAYS.
- A SOUTHERLY LAKE EFFECT SNOWBAND WILL IMPACT EASTERN UPPER MI
ON SUNDAY, BRINGING UP TO 4 INCHES OF SNOWFALL IN A NARROW
BAND NEAR MANISTIQUE.
- A CLIPPER SYSTEM MOVING THROUGH THE GREAT LAKES IS ANTICIPATED
TO BRING WIDESPREAD LIGHT SNOWFALL TO THE UP. SOME LAKE
ENHANCEMENT OVER THE FAR EAST MAY LOCALLY BOOST TOTALS UP TO
3-4 INCHES, RESULTING IN MINOR TRAVEL IMPACTS SUNDAY THROUGH
MONDAY.
- DRIER AND WARMER CONDITIONS EXPECTED BEHIND THE EARLY WEEK
SYSTEM FOR CHRISTMAS EVE AND CHRISTMAS DAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 103 PM EST SAT DEC 21 2024
GOES WATER VAPOR AND RAP ANALYSIS POSITIONS UPPER MICHIGAN WITHIN
NORTHWEST FLOW ALOFT BETWEEN MID-UPPER LEVEL TROUGHING TO OUR EAST
AND BROAD RIDGING TO OUR WEST. AT THE SURFACE, HIGH PRESSURE RIDGING
STRETCHING FROM NORTHERN ONTARIO SOUTH ACROSS LAKE SUPERIOR AND
UPPER MICHIGAN TOWARD THE MIDDLE MISSISSIPPI RIVER VALLEY HAS KEPT
WINDS LIGHT AND MOSTLY NORTHERLY ACROSS THE AREA. WITH 850MB TEMPS
ANALYZED BETWEEN -18 AND -15C AND LAKE SUPERIOR NEAR +4-6C (PER
SPC MESOANALYSIS AND GLERL RESPECTIVELY), IN ADDITION TO THE MIXED
LAYER EXTENDING TO NEAR 5K FEET THROUGH THE DGZ, THE ENVIRONMENT HAS
SUPPORTED HIGH SNOW RATIO LAKE EFFECT SNOW SHOWERS PRESSING SOUTH
INTO UPPER MICHIGAN. KMQT AND CASMR RADARS LIMIT ACTIVITY MAINLY TO
MARQUETTE COUNTY AND POINTS EASTWARD, BUT WEBCAMS HAVE SHOWN SOME
LIGHT OFF AND ON SHOWER ACTIVITY IN THE WESTERN COUNTIES. THE
STRONGEST BANDS HAVE BEEN FOCUSED ALONG THE LAKESHORE OF MARQUETTE
COUNTY DOWN TO NEAR GWINN WHERE WEAK CONVERGENCE HAS SUPPORTED
PERIODIC RADAR REFLECTIVITIES BETWEEN 30 AND 35 DBZ. THESE HIGHER
SIGNATURES HAVE BEEN MAINLY LOCATED SOUTHEAST OF THE RADAR IN A
NARROW CORRIDOR APPROXIMATELY FROM HARVEY SOUTH TO LITTLE
LAKE/GWINN BETWEEN SANDS/KSAW/GWINN AND SKANDIA/CARLSHEND. I SUSPECT
THESE LOCATIONS COULD HAVE OBSERVED A COUPLE INCHES OF SNOW THIS
MORNING, PARTICULARLY WHERE TERRAIN HAS SUPPORTED ADDITIONAL LIFT,
AND THE MOST RESTRICTIVE VISIBILITIES.
THROUGH THE REMAINDER OF THE AFTERNOON, HIGH PRESSURE WILL SLOWLY
MIGRATE THROUGH THE REGION, ENABLING FLOW TO BECOME SOUTHERLY.
GUIDANCE APPEARS TO HAVE DELAYED THIS WIND SHIFT A LITTLE, SO SNOW
SHOWERS MAY CONTINUE IN THE NORTHERN WIND SNOW BELTS INTO THE EARLY
EVENING HOURS. AT THAT POINT, SOUTHERLY FLOW WILL HELP LIFT SHOWER
ACTIVITY OVER LAKE SUPERIOR FOR THE OVERNIGHT PERIOD. IF THE SHOWERS
ARE A LITTLE SLOWER TO DIMINISH, ADDITIONAL SNOW OF AN INCH IS
GENERALLY EXPECTED WITH LOCALIZED SNOW AMOUNTS NEAR 3 INCHES NOT
BEING RULED OUT. WILL NEED TO MONITOR CAM, RADAR, AND SATELLITE
TRENDS THOUGH AFTER PUBLISHING THIS TO DETERMINE IF ANOTHER SPECIAL
WEATHER STATEMENT IS NEEDED FOR MARQUETTE COUNTY.
AFTER ACTIVITY ENDS, THE OVERNIGHT PERIOD SHOULD BE MOSTLY DRY WITH
LOWS FALLING INTO THE SINGLE DIGITS. ISOLATED SPOTS IN THE INTERIOR
WEST MAY DIP CLOSE OR JUST BELOW ZERO. JUST PRIOR TO 12Z, SOUTHERLY
FLOW WILL HELP TO SUPPORT LAKE EFFECT SNOW OFF OF LAKE MICHIGAN/BAY
OF GREEN BAY BY MORNING. RECENT CAMS ARE SUPPORTING A WIDER RANGE OF
WHERE SHOWERS MAY BE EXPERIENCED. AT THIS POINT, LIGHT SNOW SHOWERS
STREAMING NORTH MAY END UP AS FAR WEST AS ESCANABA BEFORE SUNRISE.
IF THIS DOES OCCUR, THE THOUGHT IS FOR THESE TO MIGRATE EAST INTO
SCHOOLCRAFT/MACKINAC COUNTIES. ANY SNOW EXPERIENCED PRIOR TO SUNRISE
WOULD LIKELY AMOUNT TO AN INCH OR TWO OF FLUFFY SNOW.
LONG TERM /SUNDAY THROUGH SATURDAY/
ISSUED AT 358 PM EST SAT DEC 21 2024
THE UP EXTENDED FORECAST STARTS OFF WITH NORTHWEST FLOW ALOFT AS A
TROUGH OVER NEW ENGLAND DEPARTS EAST AND SHORTWAVES RIDE SOUTHEAST
TOWARD THE GREAT LAKES. THAT SAID, A SFC LOW OVER THE SD/NE STATE
LINE AND HIGH PRESSURE SHIFTING EAST TO NEW ENGLAND RESULTS IN LOW
LEVEL SOUTHERLY FLOW. WHAT IS MORE UNUSUAL IS THAT UNDER THIS
PERSISTENT SOUTH FLOW, 850MB TEMPS OVER LAKE MI WILL START AROUND
-9C TO -12C THEN WARM TO BETWEEN -4C TO -6C FOR SUNDAY NIGHT. WITH
MUCH OF NORTHERN LAKE MI SFC TEMPS AROUND 7C, DELTA-TS WILL RANGE
FROM 11C TO AS HIGH AS 19C...SUFFICIENT FOR LES. PLACEMENT OF THE
DOMINANT SNOW BAND LOOKS TO IMPACT DELTA AND SCHOOLCRAFT COUNTIES
EARLIER, THEN EXPANDING NORTHEAST TO LUCE COUNTY AS WELL. SOME OF
THE CAMS ARE YIELDING SOME TRACE/LIGHTER SNOW AMOUNTS AS FAR WEST AS
ESCANABA EARLIER IN THE DAY, SO THERE SOME WIGGLE ROOM YET IN
PLACEMENT OF BEST LES. MODEL SOUNDINGS SHOW INITIAL MOISTURE
INHABITING A FEW KFT OF THE DGZ, RESULTING IN A SLR AROUND MID TO
UPPER TEENS:1. AS THE DAY PROGRESSES, WARMING RAISES THE DGZ HEIGHT
AND DIMINISHES THE MOISTURE WITHIN THE DGZ. AS A RESULT, SLRS LOWER
TO AROUND 10:1 FOR SUNDAY NIGHT INTO MONDAY. IN ADDITION, A WEAK
SHORTWAVE AND WAA RIPPLING OVER NORTHERN WI MAY RESULT IN SOME
FLURRIES IN THE CENTRAL UP SUNDAY AFTERNOON AND EVENING AHEAD OF THE
SFC LOW.
SYSTEM SNOW BEGINS TO RAMP UP SUNDAY NIGHT WITH AN APPROACHING SFC
LOW FROM THE WEST. THE BETTER DYNAMIC SUPPORT LOOKS TO MAINLY REMAIN
SOUTH OF THE UP OVER WI/LOWER MI, BUT SOME WIDESPREAD LIGHT SNOW IS
EXPECTED UP TO 2" ACROSS THE UP (HIGHEST SOUTH CENTRAL AND EAST).
ADDITIONAL LAKE ENHANCEMENT OFF LAKE MI IS LIKELY WITH THIS SYSTEM,
YIELDING UP TO 3-4" OF SNOW OVER AREAS IN SCHOOLCRAFT AND LUCE
COUNTIES. BETWEEN THE LES AND SYSTEM SNOW, SOME WINTER WEATHER
ADVISORIES MAY BE NEEDED FOR THE EAST. OPTED TO HOLD OFF FOR NOW
GIVEN THE LES BAND IS STILL SHIFTING AROUND AND SFC LOW TRACK ALSO
HAS SOME SPREAD IN TRACK. SOME TRAILING LAKE ENHANCED SNOW OFF LAKE
SUPERIOR FOR THE NORTH HALF OF UPPER MI IS POSSIBLE (15-30%) MONDAY
AFTERNOON AND EVENING, BUT ACCUMULATIONS WILL BE LOW (<1") WITH A
LESS THAN IDEAL THERMODYNAMIC PROFILE.
DRY WEATHER RETURNS BY TUESDAY AS HIGH PRESSURE DESCENDS OVER THE
GREAT LAKES. A PATTERN OF MAINLY MID LEVEL RIDGING RETURNING THE
EASTERN CONUS BRINGS WARMER THAN NORMAL TEMPS BACK TO THE REGION.
HOW LONG THE DRY PERIOD LASTS EARLY NEXT WEEK WILL DEPEND ON WHEN
THE NEXT SHORTWAVE MOVES THROUGH. GUIDANCE SPREADS QUICKLY WITH
SHORTWAVE TIMING AND TRACK AS WELL AS LATER SYSTEMS IN THE WEEK, BUT
THERE IS A CONSENSUS ON A LOW PRESSURE SYSTEM TRACKING NORTHEAST
THROUGH THE UPPER GREAT LAKES LATE NEXT WEEK/EARLY NEXT WEEKEND.
WITH HIGHS WARMING WELL INTO THE 30S TO POSSIBLY LOW 40S WITH LOWS
LIFTING TO NEAR FREEZING BY THEN, THE PRIMARY P-TYPE MOVING FORWARD
WILL BE RAIN. THIS ALONGSIDE DEW POINTS LIFTING TO NEAR FREEZING
LATE NEXT WEEK WILL RESULT IN MELTING SOME OF THE SNOWPACK IN THE
COMING DAYS. THAT SAID, MUCH OF THE UP SHOULD STILL HAVE SOME SNOW
ON THE GROUND FOR CHRISTMAS. A RETURN OF COLDER AIR LOOKS TO HOLD
OFF UNTIL THE NEW YEAR.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1214 PM EST SAT DEC 21 2024
LAKE EFFECT CLOUD AND SNOW SHOWERS WILL CONTINUE TO PRESS SOUTH INTO
CENTRAL UPPER MICHIGAN, BRINGING SHOWERS TO KSAW THIS AFTERNOON.
BEFORE ACTIVITY ENDS LATER THIS AFTERNOON, EXPECT TEMPORARY LIFR
CONDITIONS AS THESE SHOWERS MOVE OVER THE TERMINAL.
OTHERWISE, ALL TERMINALS WILL TREND TOWARD VFR THIS EVENING AND
OVERNIGHT WITH LIGHT WINDS. BY MORNING, ANOTHER SYSTEM APPROACHING
THE AREA FROM THE WEST WILL WORK TO INCREASE THE PRESSURE GRADIENT
OVER THE AREA. THIS WILL RESULT IN GUSTY SOUTHERLY OF 20-25KTS WINDS
AT ALL TERMINALS SUNDAY.
MARINE
ISSUED AT 358 PM EST SAT DEC 21 2024
SOUTHERLY WINDS INCREASE THIS AFTERNOON THROUGH TONIGHT AS HIGH
PRESSURE SHIFTS TOWARD THE LOWER GREAT LAKES AND A LOW PRESSURE
SYSTEM APPROACHES FROM THE WEST. SOUTH WINDS OF 20-30 KTS ARE
EXPECTED ON SUNDAY WITH THE INCREASED PRESSURE GRADIENT ACROSS THE
LAKE. STRONGEST WINDS ARE EXPECTED OVER THE EAST HALF OF THE LAKE
WHERE THERE IS A 15% OR LESS CHANCE FOR GALES TO 35+ KTS. THESE
WINDS BUILD WAVES UP TO 5-8 OVER THE NORTHEAST, MAINLY NORTH OF THE
INTERNATIONAL BORDER SUNDAY AND SUNDAY NIGHT. WINDS WEAKEN TO 15-25
KTS SUNDAY NIGHT AS THEY GRADUALLY VEER SOUTHWEST, BUT QUICKLY
BECOME NORTHWEST BEHIND A FRONTAL BOUNDARY EARLY ON MONDAY. WINDS
MAINLY HOLD 20 KTS OR LESS MONDAY ONWARD AS THE LOW DEPARTS FROM THE
GREAT LAKES AND HIGH PRESSURE RETURNS, BUT TURN SOUTHERLY FOR THE
BACK HALF OF NEXT WEEK.
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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