394
FXUS63 KMQT 212038
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
338 PM EST TUE JAN 21 2025
KEY MESSAGES
- ARCTIC AIR BEGINS TO MODIFY TONIGHT. MINIMUM TEMPERATURES OF
-5 TO 15F WILL OCCUR THIS EVENING, THEN TEMPERATURES WILL
SLOWLY RISE. COLD WEATHER ADVY FOR LOW WIND CHILLS REMAINS IN
EFFECT ACROSS THE ENTIRE FORECAST AREA UNTIL 06Z TONIGHT.
- MODERATING AIRMASS WILL SEE TEMPERATURES TRENDING MORE OR
LESS TOWARDS NORMAL VALUES FROM MIDWEEK ONWARDS.
- PASSING CLIPPER SYSTEMS WILL BRING IN ROUNDS OF LIGHT LAKE
EFFECT/ENHANCED SNOW THROUGH THE EXTENDED PERIOD, BUT
WIDESPREAD SIGNIFICANT SNOWFALL IS NOT EXPECTED.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 337 PM EST TUE JAN 21 2025
WATER VAPOR IMAGERY AND RAP ANALYSIS SHOW MID-LEVEL RIDGING JUST OFF
OF THE W COAST EXTENDING INTO AK/NW CANADA AND A DEEP TROF OVER
EASTERN N AMERICA. THIS PATTERN HAS FORCED ARCTIC AIR INTO THE
CENTRAL AND EASTERN U.S. THE TROFFING IS BEGINNING TO RELAX NOW AS
WAA IS SPREADING ACROSS THE PLAINS IN RESPONSE TO A SHORTWAVE
DROPPING THRU ALBERTA/SASKATCHEWAN. ANOTHER SHORTWAVE IS DROPPING S
TOWARD NORTHERN MANITOBA. CLOSER TO HOME, LOW-LEVEL WINDS HAVE
ALREADY BACKED TO THE SW, SHIFTING ALL LAKE SUPERIOR LES OFFSHORE OF
UPPER MI. DESPITE SUNNY SKIES, TEMPS ONLY RANGE MOSTLY THRU THE
NEGATIVE SINGLE DIGITS F ACROSS MUCH OF THE FCST AREA AT 20Z. SOME
LOCATIONS ACROSS THE E HAVE PUSHED JUST ABOVE 0F.
WAA/ISENTROPIC ASCENT WILL STRENGTHEN INTO THE UPPER GREAT LAKES
TONIGHT IN RESPONSE TO THE AFOREMENTIONED WAVES. PER 275/280/285K
SFCS, 30-40KT WINDS BECOME ORIENTED NEARLY PERPENDICULAR TO THE
ISOBARS, BUT PRES STEADILY RISES ON THOSE SFCS, INDICATING THAT NOT
ALL OF THE ADVECTION IS GOING INTO LIFT. COMBINED WITH A LACK OF
MOISTURE, NOT EXPECTING MUCH SNOW TO DEVELOP IN THIS WAA/ISENTROPIC
ASCENT REGIME. FCST REFLECTS MOSTLY A 30-60PCT CHC OF -SN BEGINNING
W NEAR MIDNIGHT AND SPREADING EASTWARD OVERNIGHT. WINDS SHOULD BACK
JUST ENOUGH TO BRING SOME LAKE ENHANCEMENT OFF OF LAKE MI INTO FAR
SE SCHOOLCRAFT COUNTY AND SE LUCE COUNTY BY 12Z. SNOW ACCUMULATIONS
WILL BE LESS THAN 1 INCH WITH PALTRY MOISTURE AVBL (MIXING RATIOS
AROUND 1G/KG IN ROUGHLY THE 700-750MB LAYER).
MIN TEMPS RANGING BTWN -5 AND -15F WILL OCCUR THIS EVENING BEFORE
CLOUDS INCREASE/THICKEN AND LOW-LEVEL WINDS INCREASE FURTHER,
RESULTING IN TEMPS SLOWLY RISING. THE COLD CONDITIONS ALONG WITH
WIND SUPPORT COLD WEATHER ADVY THRU THE EVENING HOURS. THE 06Z END
TIME FOR THE ADVY APPEARS OK FOR NOW AS SLOWLY RISING TEMPS RESULT
IN APPARENT TEMPS CROSSING ADVY CRITERIA THRESHOLD OVER MUCH OF THE
AREA AT AROUND THAT TIME.
LONG TERM /WEDNESDAY THROUGH MONDAY/
ISSUED AT 257 PM EST TUE JAN 21 2025
A MORE ACTIVE PATTERN LOOKS TO SET UP FOR THE MIDWEEK AND BEYOND AS
THE FIRST IN A SERIES OF SHORTWAVES TRANSITS THROUGH THE MIDWEST
REGION ON WEDNESDAY. WHILE DETAILS IN TIMING AND INTENSITY OF THE
FOLLOWING SHORTWAVES IS STILL HIGH, THERE IS A GENERAL AGREEMENT ON
A BRIEF PERIOD OF LOCAL RIDGING FOR FRIDAY BEFORE ANOTHER SHORTWAVE
PASSES FRIDAY INTO THE WEEKEND. FROM THERE, MORE SHORTWAVES (WITH
PLENTY OF SPREAD AMONG MODELS, AND VARYING DEGREES OF
STRENGTH/TIMING) ARE EXPECTED THROUGH THE REST OF THE PERIOD. THESE
ARE EMBEDDED IN BROAD TROUGHING OVER THE GREAT LAKES AS A SPLIT FLOW
PATTERN SETS UP WITH A CUTOFF LOW OVER THE DESERT SOUTHWEST.
WEDNESDAY MORNING, A WEAKENING CLIPPER LOW WILL BE MOVING ALONG THE
BORDER OF NORTHERN MN, SET TO TRACK ALONG/NORTH OF LAKE SUPERIOR
THROUGH THE AFTERNOON. HIGH PRESSURE EXTENDING FRO THE MID ATLANTIC
SOUTHWEST TO TEXAS WILL CUT US OFF FROM THE GULF OF MEXICO (AND ITS
MUCH-NEEDED MOISTURE), AND GIVEN PRIOR SIMILAR SETUPS IN MOISTURE-
STARVED CLIPPERS THIS SEASON, ONLY A COUPLE TO A FEW TENTHS OF
SNOWFALL ARE EXPECTED WITH THIS SYSTEM AS IT PASSES WEDNESDAY. ONE
FEATURE TO WATCH WITH THE WEDNESDAY SYSTEM IS ANY POTENTIAL
SOUTHERLY TO SOUTHWESTERLY LAKE EFFECT/ENHANCED SNOWFALL AS DESPITE
THE RELATIVELY WARM ADVECTION, 850MB TEMPERATURES ARE STILL EXPECTED
TO BE IN THE NEGATIVE TEENS ABOVE AN OPEN LAKE MICHIGAN. CAMS
CONTINUE TO SHOW STRONGER BANDING EXTENDING INTO MACKINAC AND
CHIPPEWA COUNTIES, JUST EAST OF OUR CWA. HOWEVER, IF FUTURE FORECAST
CYCLES SHIFT THIS MORE WESTERLY, AT LEAST LUCE COUNTY COULD BE
CLIPPED BY SOME ADVISORY AMOUNTS.
OTHERWISE, MAINLY LIGHT NORTHWESTERLY LAKE EFFECT SNOWFALL IS
EXPECTED IN THE WAKE OF THE TROUGH'S PASSAGE WITH LREF 6-HOURLY
PRECIP RATES FOR WEDNESDAY EVENING THROUGH THURSDAY ARE ONLY AROUND
0.01-0.05", AND SOME LOCALLY HIGHER AMOUNTS UP TO 0.10" WEDNESDAY
NIGHT WHERE ANY LOCALIZED TERRAIN ENHANCEMENT CAN OCCUR IN THE
WESTERN UP. WILL ALSO NOTE THAT SOME OF THE LATEST CAM GUIDANCE IS
HINTING AT SOME LOCALLY HIGHER AMOUNTS IN THE EASTERN UP WEDNESDAY
EVENING/NIGHT WITH SOME LOCALIZED CONVERGENCE OR MESO-LOW
DEVELOPMENT MOVING ONSHORE FROM EASTERN LAKE SUPERIOR. WITH SNOW
RATIOS ONLY PEAKING AT AROUND 20:1, AROUND AN AN INCH OF SNOW PER
SIX HOURS IS EXPECTED FOR THE MOST PART ACROSS THE NW WIND SNOW
BELTS WED-THURS, WITH LOCALLY HIGHER AMOUNTS TO 1-2IN/6HRS WEDNESDAY
EVENING AND NIGHT IN THOSE AREAS OF LOCALIZED ENHANCEMENT. INTO
THURSDAY, SLOWLY BACKING WINDS AND A DRIER AIRMASS WORKING IN AS A
RIDGE SLOWLY BUILDS INTO THE GREAT LAKES WILL CUT BACK ON SNOWFALL
ACCUMULATIONS THROUGHOUT THE DAY.
MEANWHILE, TEMPERATURES CONTINUE TO COME IN SLIGHTLY BELOW AVERAGE
WEDNESDAY THROUGH THURSDAY, BUT MORE SEASONABLE AIR IS EXPECTED TO
RETURN TO THE AREA LATE WEEK WITH HIGHS GENERALLY IN THE TEENS AND
20S AND LOWS IN THE SINGLE DIGITS. AS LONG AS LAKE SUPERIOR REMAINS
IN ITS CURRENT MAINLY ICE-FREE STATE, TEMPERATURES ALOFT CONTINUE TO
SUPPORT LAKE EFFECT SNOW IN THE WAKE OF ANY PASSING SHORTWAVES. FOR
THE WEEKEND AND BEYOND, THE MOST COMMON 925MB WIND DIRECTION REMAINS
NWERLY, SO THAT WILL CONTINUE TO BE THE EXPECTED REGIME FOR LES
BANDS TO SET UP IN FOLLOWING ANY CLIPPERS. HOWEVER, STRONG SYNOPTIC
SNOWS LOOK UNLIKELY UNTIL AT LEAST NEXT WEEK, WHEN THERE'S A WEAK
SIGNAL IN THE ENSEMBLES FOR A SUB-900MB LOW TO PASS...SOMEWHERE
THROUGH OR NEAR THE GREAT LAKES. SPREAD IS HIGH AT THIS TIME PERIOD,
SO THIS PROSPECTIVE SYSTEM IS JUST AS LIKELY TO MISS THE UP AS IT IS
TO PROVIDE ANY WINTER IMPACTS. CPC OUTLOOKS FOR EARLY FEBRUARY
HIGHLIGHT SLIGHT FAVORING OF COOLER THAN NORMAL TEMPERATURES AND
HIGHER PRECIPITATION THAN NORMAL FOR THE UPPER GREAT LAKES REGION.
THIS LIKELY STEMS FROM ENSEMBLE MEAN 500MB HEIGHT CHARTS FAVORING
TROUGHING STRETCHING FROM NORTHEAST CANADA TO THE GREAT LAKES AND
RIDGING OVER WESTERN NORTH AMERICA, FAVORING TRANSPORT OF COOLER AIR
OVER STILL-OPEN WATERS OF THE GREAT LAKES (SAVE FOR BAYS, ETC THAT
ARE ICING OVER CURRENTLY) WHICH SHOULD SUPPORT CONTINUED LES.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1250 PM EST TUE JAN 21 2025
WITH WINDS BACKING TO THE SW, LAKE EFFECT SHSN HAVE ENDED AT CMX,
BUT BLSN DUE TO WINDS GUSTING 20-25KT WILL CONTINUE TO CAUSE
FLUCTUATION IN VIS BTWN MVFR AND IFR FOR THE NEXT FEW HRS, THEN
CONDITIONS WILL IMPROVE TO VFR LATE AFTN/EARLY EVENING. VFR WILL
PREVAIL AT IWD/SAW INTO THE EVENING HOURS. LATER TONIGHT INTO WED
MORNING, AN APPROACHING DISTURBANCE WILL BRING LOWERING CIGS AND
SOME -SN TO THE AREA. CONDITIONS WILL FALL TO MVFR AT IWD/CMX
OVERNIGHT AND AT SAW EARLY WED MORNING. A PERIOD OF IFR IS POSSIBLE
AS WELL, ESPECIALLY AT CMX. S TO SW WINDS WILL BE GUSTY TO ABOUT
20KT AT IWD THIS AFTN AND TO AROUND 25KT TONIGHT INTO WED MORNING
BEFORE DIMINISHING. AT CMX, EXPECT GUSTS TO 20-25KT TODAY AND UP TO
20KT TONIGHT. GUSTS AT SAW WILL REACH TO 20-25KT LATE EVENING INTO
WED MORNING.
MARINE
ISSUED AT 257 PM EST TUE JAN 21 2025
FOR TODAY, WESTERLY WINDS WILL BACK SOUTHWESTERLY AHEAD OF AN
APPROACHING CLIPPER LOW. A FEW ISOLATED GALE FORCE GUSTS ARE
EXPECTED LATE THIS EVENING THROUGH TONIGHT, ESPECIALLY ACROSS THE
WEST HALF OF THE LAKE, BUT CONFIDENCE OF MORE WIDESPREAD COVERAGE AT
ANY GIVEN TIME IS TOO SMALL TO ISSUE A GALE WARNING. AN APPROACHING
CLIPPER LOW ON WEDNESDAY WILL BRING SOUTHWESTERLY WIND GUSTS UP TO
NEAR 30 KT, VEERING TO THE NW OVERNIGHT, WITH CHANCES OF GALES OF
AROUND 30-50% WEDNESDAY TO WEDNESDAY NIGHT ACROSS THE EASTERN HALF
OF THE LAKE. AS HIGH PRESSURE INFLUENCES THE FORECAST FOR THURSDAY,
MAINLY WESTERLY WINDS AROUND 20-25 KT ARE EXPECTED. FOR FRIDAY INTO
THE WEEKEND, PRIMARILY WESTERLY AND SOUTHWESTERLY WINDS AROUND 25 KT
ARE EXPECTED, BUT GALES TO 35 KNOTS ARE POSSIBLE INTO EARLY SUNDAY
(AROUND 30-50% CHANCE) AS WINDS SHIFT TO THE NW AGAIN BEHIND A
PASSING CLIPPER SYSTEM. NW WINDS REMAIN ELEVATED AT AROUND 20-30KTS
INTO EARLY NEXT WEEK. WITH SOME OF THE MOST FRIGID AIR OF THE LAST
FEW YEARS OVER LAKE SUPERIOR, HEAVY FREEZING SPRAY WARNINGS ARE IN
EFFECT THROUGH AT LEAST WEDNESDAY MORNING AS WAVES OF UP TO 10 FEET
FEET WILL ALLOW FOR SUPERCOOLED SPRAY TO FORM.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
COLD WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ WEDNESDAY
FOR MIZ001>007-009>014-084-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/
WEDNESDAY FOR LSZ162-240>251-263>267.
LAKE MICHIGAN...
NONE.
SHORT TERM...ROLFSON
LONG TERM...LC
AVIATION...ROLFSON
MARINE...LC
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