576
FXUS63 KMQT 210749
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
249 AM EST SAT DEC 21 2024
KEY MESSAGES
- LIGHT TO MODERATE LAKE EFFECT SNOWFALL CONTINUES OVERNIGHT,
SHIFTING TO THE NORTH WIND SNOW BELTS BY SATURDAY MORNING.
BEST ACCUMULATIONS EXPECTED OVER NORTH CENTRAL UPPER MI.
- 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 249 AM EST SAT DEC 21 2024
UPPER AIR PATTERN CONSISTS OF A DEEP 500 MB TROUGH IN THE EASTERN
U.S. AND A TROUGH OFF THE WEST COAST WITH A RIDGE OVER THE WESTERN
U.S. AND ROCKIES 06Z SAT. A SHORTWAVE EJECTS OUT OF THE WEST COAST
TROUGH INTO THE NORTHERN ROCKIES BY 12Z SUN. LAKE EFFECT SNOW WILL
CONTINUE TO SLOWLY WIND DOWN TODAY. SOUNDINGS DID SHOW INVERSION
HEIGHT BELOW 5000 FEET, BUT DGZ IN THE DEEPER MOISTURE, SO LSRS WILL
CONTINUE TO BE HIGH FOR TODAY. WILL ISSUE A SPECIAL WEATHER
STATEMENT AS A SMALL AREA OF MARQUETTE COUNTY SOUTH OF MARQUETTE TO
GWINN IN THE HIGHER TERRAIN COULD SEE UP TO 5 INCHES OF SNOW FROM
NOW UNTIL 18Z THIS AFTERNOON. DRIES OUT THIS EVENING, THEN A LAKE
MICHIGAN BAND SETS UP LATE TONIGHT WITH A SWITCH IN THE WINDS TO THE
SOUTH OVER THE EASTERN CWA. THIS JUST GETS STARTED LATE TONIGHT.
HUNG ONTO POPS LONGER OVER THE EASTERN CWA TODAY AS THE TENDENCY IS
ALWAYS TO END THEM TOO SOON, OTHERWISE DID NOT MAKE TOO MANY CHANGES
TO THE GOING FORECAST.
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 /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1153 PM EST FRI DEC 20 2024
LOW-LEVEL NORTHERLY WINDS AHEAD OF HIGH PRES APPROACHING FROM THE NW
ALONG WITH A CHILLY AIR MASS FLOWING ACROSS LAKE SUPERIOR WILL
SUPPORT MVFR CIGS AND LAKE EFFECT -SHSN/FLURRIES THRU THIS MORNING
AT IWD/CMX/SAW. THE -SHSN WILL BE MOST FREQUENT AND A LITTLE HEAVIER
AT SAW, LIKELY RESULTING IN PREVAILING MVFR VIS AND OCNL BRIEF IFR
VIS OVERNIGHT THRU THE MORNING. ONLY OCNL FLURRIES ARE EXPECTED AT
IWD WITH NO VIS RESTRICTION OUT OF VFR. CMX WILL SEE SOME PERIODS OF
MVFR VIS DURING THE NIGHT WITH BRIEF IFR ALSO A POSSIBILITY. AS HIGH
PRES PASSES, MVFR CIGS WILL SCATTER OUT TO VFR AT IWD LATE THIS
AFTN, AT CMX AROUND 00Z AND AT SAW NEAR THE END OF THE FCST PERIOD.
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...07
LONG TERM...JTP
AVIATION...ROLFSON
MARINE...JTP
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