247
FXUS63 KMQT 202019
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
319 PM EST FRI DEC 20 2024
KEY MESSAGES
- LIGHT TO MODERATE LAKE EFFECT SNOWFALL CONTINUES INTO TONIGHT,
SHIFTING TO THE NORTH WIND SNOW BELTS BY SATURDAY MORNING.
BEST ACCUMULATIONS EXPECTED OVER NORTH CENTRAL UPPER MI LATE
TONIGHT/SATURDAY MORNING.
- CLIPPER MOVING THROUGH THE GREAT LAKES COULD BRING A
WIDESPREAD SNOW SUNDAY NIGHT INTO MONDAY.
- DRIER AND WARMER CONDITIONS EXPECTED BEHIND THE EARLY WEEK
SYSTEM FOR CHRISTMAS EVE AND CHRISTMAS DAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 319 PM EST FRI DEC 20 2024
THIS AFTERNOON'S RAP ANALYSIS SHOWS THE CLIPPER SYSTEM NOW BEGINNING
TO PHASE WITH ANOTHER SFC LOW AT ~1003MB LOCATED EAST OF MD OUT OVER
THE ATLANTIC. MEANWHILE, A 1037MB HIGH PRESSURE IS POSITIONED OVER
SOUTHEAST MANITOBA AND NORTHERN MN AND A MID LEVEL TROUGH IS
BEGINNING TO DIP OVER THE UP. ON THE GROUND, SFC OBS ARE SHOWING
TEMPS IN THE UPPER TEENS TO 20S, LIKELY OUR HIGHS FOR THE DAY AND
LAKE SFC TEMPS ARE AVERAGING AROUND 4.8C. ALOFT, 850MB TEMPS ARE
AROUND -16C ACROSS LAKE SUPERIOR YIELDING DELTA-TS OF ~20C,
SUPPORTIVE OF THE LAKE EFFECT CLOUDS ACROSS THE UP WITH LIGHT LES
MAINLY OVER THE NORTH CENTRAL AND EAST. THE LIMITING FACTOR FOR
SNOW IS THE DRY AIR ADVECTING IN.
AS THE TROUGH DROPS OVER THE UP THROUGH THIS EVENING, 850MB TEMPS
LOWER FURTHER TO -18C TO -20C OVER THE EAST HALF OF THE LAKE
INCREASING THE DELTA-TS. WITH THAT BUMP IN VERTICAL MOTION ALONGSIDE
INCREASED DELTA-TS, SHOWER COVERAGE LOOKS TO RE-INVIGORATE INTO THE
EVENING HOURS. HOWEVER, INCREASING SFC HIGH PRESSURE FROM THE
NORTHWEST BRINGS IN DRIER AIR AND LOWERS INVERSION HEIGHTS TO AROUND
5KFT OR LESS. ALSO, MOISTURE WITHIN THE DGZ IS NOT CONSISTENTLY
NOTED IN THE MODEL SOUNDINGS. AS WINDS SHIFT NORTHERLY, GUIDANCE
INDICATES A MORE DOMINANT LES BAND SUPPORTED BY LAKE NIPIGON
UPSTREAM PRETREATMENT DEVELOPING THIS EVENING, THEN SHIFTING WEST
OVERNIGHT TO MARQUETTE COUNTY BY SATURDAY MORNING. WHILE THIS DOES
HAVE SUPPORT FROM LOW LEVEL CONVERGENCE, AN IDEAL FETCH ACROSS LAKE
SUPERIOR AND ASSISTANCE FROM LAKE NIPIGON, THE INCREASING DRY AIR
AND DIMINISHING CYCLONIC FLOW WILL LIMIT ACCUMULATIONS AND
ASSOCIATED IMPACTS. THE HRRR HAS BEEN VERY CONSISTENT IN YIELDING
ADVISORY ACCUMULATIONS, HOWEVER THE QPF (APPROACHING 0.15" TO 0.2")
SEEMS TOO HIGH GIVEN THE SET UP DESCRIBED ABOVE. THE FORECASTED
TOTAL SNOWFALL FROM THIS AFTERNOON THROUGH TONIGHT ALIGNS WITH THE
GENERAL SOLUTION AMONG MODEL GUIDANCE. THIS CALLS FOR AN INCH OR
LESS OF DRY AND FLUFFY SNOW, MAINLY NORTH CENTRAL AND EAST. ISOLATED
AMOUNTS UP TO 2-3 INCHES CAN'T BE RULED OUT INTO SATURDAY MORNING,
BUT PLACEMENT OF THAT BAND STILL IS NOT SOLID.
OTHERWISE, NORTHERLY WINDS TURN LIGHT TONIGHT AND LOWS SETTLE INTO
THE SINGLE DIGITS AROUND 0... EXCEPT LOW TO MID TEENS BY THE
LAKESHORES. EXPECT WIND CHILLS TO DIP BELOW 0.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 254 PM EST FRI DEC 20 2024
LAKE EFFECT SNOW SHOWERS OFF OF LAKE SUPERIOR WILL TAPER OFF
SATURDAY AS SURFACE HIGH PRESSES INTO WISCONSIN AND DRY AIR AND
SUBSIDENCE SUPPORT DRIER CONDITIONS. GUIDANCE SUGGESTS THAT LAKE
EFFECT SHOULD BE DIMINISHED ACROSS THE FORECAST AREA BY SATURDAY
EVENING. BEFORE THEN THOUGH, ADDITIONAL SNOWFALL AMOUNTS COULD CLIMB
ANOTHER INCH OR SO, MAINLY FROM MARQUETTE INTO WESTERN ALGER.
SOUTHERLY FLOW WILL SETTLE IN SATURDAY NIGHT. ITS POSSIBLE THIS
COULD SUPPORT LIGHT LAKE EFFECT SNOW OFF OF LAKE MICHIGAN INTO
EASTERN DELTA, SCHOOLCRAFT, AND LUCE COUNTIES SUNDAY, PERHAPS
YIELDING AN INCH OR TWO OF SNOW.
BROAD MID-UPPER LEVEL RIDGE TO TROUGH PATTERN STRETCHING ACROSS
CONUS AND CANADA THIS WEEKEND WILL GRADUALLY BREAK DOWN AS A
SHORTWAVE DIGS SOUTHEAST WITHIN THE NORTHWEST FLOW OVER THE WESTERN
PLAINS. AS THIS CLIPPER LOW PRESSES ACROSS THE NORTHERN PLAINS
SUNDAY NIGHT, A SURFACE LOW WILL DEVELOP AND PRESS NORTHEAST INTO
MINNESOTA. BY EARLY MONDAY, GENERAL CONSENSUS AMONG THE VARIOUS
DETERMINISTIC PACKAGES SUGGESTS THE NOW VERTICALLY STACKED FEATURE
WILL PRESS EASTWARD TO NEAR MENOMINEE DURING THE DAY AND THEN
EASTWARD OVERNIGHT INTO TUESDAY. THERE ARE SOME OUTLIERS THOUGH,
NAMELY THE NAM, WHICH BRINGS THE SYSTEM CLOSE TO THUNDER BAY. WHILE
THERE IS SOME SUPPORT FROM A COUPLE ENSEMBLE MEMBERS OF THE EC,
GEFS, AND GEPS, WILL TREAT THE NORTHERN SOLUTION AS AN OUTLIER IN
THIS FORECAST PACKAGE FOR THE TIME BEING. THE TRACK OF THE CONSENSUS
WOULD RESULT IN SYNOPTIC PRECIP SPREADING INTO THE AREA SUNDAY NIGHT
THROUGH MONDAY, FOLLOWED BY SOME LAKE EFFECT POTENTIAL INTO TUESDAY.
THE LAKE EFFECT IS LESS CERTAIN GIVEN THE SPEED AT WHICH RIDGING AND
WAA LIMITS SHOWER DEVELOPMENT. DESPITE THE AIRMASS ALOFT WARMING
WITH THE SYSTEM, IT STILL SHOULD BE COLD ENOUGH FOR PTYPE TO BE
PRIMARILY SNOW. SNOW WOULD BE WETTER THOUGH, WITH NBM SUGGESTING
SNOW RATIOS CLOSE TO 10:1. QPF IS LESS CERTAIN GIVEN THE POSSIBILITY
OF LAKE ENHANCEMENT OFF LAKE MICHIGAN INTO EASTERN UPPER MICHIGAN.
AT THIS POINT THOUGH, 0.10 TO 0.5 INCHES OF LIQUID (HIGHEST EAST -
LEAST WEST) LOOKS POSSIBLE, POTENTIALLY YIELDING 1 TO 5 INCHES OF
SNOW WITH ISOLATED HIGHER SPOTS BEING POSSIBLE (HIGHEST EAST - LEAST
WEST) SUNDAY NIGHT THROUGH MONDAY. THERE'S LESS SUPPORT WHEN
CONSIDERING SNOW AMOUNT PROBABILITIES FROM THE GEPS AND EC THOUGH.
THESE SUGGEST THE EAST HAS A 10-30% CHANCE OF SEEING AT LEAST 3
INCHES. THIS MAY HAVE SOMETHING TO DO WITH THE TRACK UNCERTAINTY OR
THE DIFFERENCES IN WARM AIR WHICH WILL IMPACT SNOW RATIOS. AT THIS
POINT THOUGH, WE'LL NEED TO CONTINUE MONITORING TRENDS THIS WEEKEND
TO BETTER IDENTIFY AMOUNTS AND POTENTIAL IMPACTS.
WARM AIR WILL PRESS INTO THE REGION AFTER THIS SYSTEM EXITS THE
REGION. DETERMINISTICS SUGGESTS 850MB TEMPS COULD WARM ABOVE 0C BY
CHRISTMAS MORNING, AND THEN LINGER BETWEEN +1 AND 3C THROUGH AT
LEAST THE FOLLOWING WEEKEND. THIS WARM AIRMASS WOULD SUPPORT
TEMPERATURES CLIMBING WELL INTO THE 30S WHILE OVERNIGHT LOWS DIP
ONLY INTO THE 20S. SOME LAKESHORE AREAS MAY EVEN STAY ABOVE FREEZING.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 116 PM EST FRI DEC 20 2024
NORTHWEST WIND LAKE EFFECT SNOW SHOWERS CONTINUE TO STREAM OVER THE
UP THIS AFTERNOON AND ARE EXPECTED TO CONTINUE INTO SATURDAY AS THEY
TURN MORE NORTHERLY. THIS WILL MAINLY IMPACT SAW DURING THE 18Z TAF
PERIOD, HOWEVER SOME SNOW SHOWERS LOOK TO RETURN TO CMX THIS EVENING
AND TONIGHT. CLOUD BASES WILL PRIMARILY BE MVFR, BUT FEW/SCT CLOUD
DECKS ARE LIKELY BY LATE THIS AFTERNOON/EARLY EVENING AT IWD/CMX
BEFORE SKY COVERAGE INCREASES AND CIGS LOWER LATER TONIGHT.
DEPENDING ON WHERE A DOMINATING LAKE EFFECT BAND SETS UP LATE
TONIGHT, SOME IFR CONDITIONS ARE POSSIBLE AT SAW LATE. OPTED TO HOLD
OF ON IFR OR LOWER FLIGHT RESTRICTIONS WITH SOME UNCERTAINTY YET
REGARDING LAKE EFFECT BAND PLACEMENT.
MARINE
ISSUED AT 254 PM EST FRI DEC 20 2024
NORTHWEST 20 TO 30KT WINDS WILL GRADUALLY TAPER THIS EVENING,
EVENTUALLY FALLING BELOW 20KTS SATURDAY MORNING LAKE-WIDE. THESE
LIGHT WINDS WILL CONTINUE INTO EARLY SUNDAY MORNING, WHEN SOUTHERLY
WINDS BEGIN INCREASING AS THE NEXT SYSTEM APPROACHES THE GREAT
LAKES. THERE IS SOME UNCERTAINTY IN THE TRACK OF THE SYSTEM, BUT THE
CURRENT CONSENSUS AGREES ON PRESSURE GRADIENT INCREASING, WHICH WILL
WORK TO ENHANCE LOW LEVEL SOUTHERLY FLOW DURING THE DAY SUNDAY AND
SUNDAY NIGHT. 925MB WINDS AMONG THE GUIDANCE PACKAGES ARE SOUTHERLY
WINDS OF 30-40 KTS, WITH THE STRONGEST WINDS ACROSS EASTERLY LAKE
SUPERIOR. THERE SHOULD BE ENOUGH COLD AIR ALOFT AT THIS TIME TO MIX
STRONGER WINDS TO THE SURFACE, BUT HOW STRONG IS UNCERTAIN. GOING
FORECAST IS FOR WINDS TO INCREASE TO NEAR 30KTS, BUT CAN'T RULE OUT
SOME GALES. LATEST EC ENSEMBLE SYSTEM SUGGESTS GALE PROBABILITIES
BETWEEN 10 AND 40% ACROSS EASTERN LAKE SUPERIOR. MODEL SOUNDINGS
ALSO SUGGEST THIS COULD END UP BEING A DOWNSLOPING WIND EVENT NEAR
THE UPPER MICHIGAN LAKESHORES EAST OF MARQUETTE. SO THESE NEARSHORE
AREAS MAY NOT BE REMOVED FROM THE STRONGER WINDS EITHER.
WINDS WILL SETTLE WEST TO EAST SUNDAY NIGHT INTO MONDAY. A WARMER
THAN NORMAL AIRMASS WILL SETTLE OVER THE AREA AFTERWARDS. THIS LOOKS
TO HELP MAINTAIN LIGHT WINDS FOR A MAJORITY OF NEXT WEEK.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...JABLONSKI
LONG TERM...JTP
AVIATION...JABLONSKI
MARINE...JTP
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