618
FXUS63 KMQT 311102
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
702 AM EDT SUN AUG 31 2025
KEY MESSAGES
- PATCHY DENSE FOG IS POSSIBLE ACROSS THE INTERIOR PORTIONS OF
UPPER MICHIGAN EARLY THIS MORNING.
- ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE (20 TO 40%
CHANCE) THIS AND LABOR DAY AFTERNOONS, MAINLY OVER THE WEST
HALF.
- A COLD FRONT WILL MOVE THROUGH THE REGION TUESDAY NIGHT AND
WEDNESDAY. THIS WILL BRING WIDESPREAD RAIN TO UPPER MICHIGAN
AND STRONG WINDS TO THE KEWEENAW.
- A COOL AIRMASS WILL BUILD OVER THE UPPER GREAT LAKES LATE THIS
WEEK.
- THERE IS A 20-40% CHANCE FOR NORTHWEST GALES TUESDAY NIGHT
INTO WEDNESDAY, MAINLY WEST AND NORTH OF THE KEWEENAW
PENINSULA.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 337 AM EDT SUN AUG 31 2025
HIGH PRESSURE RIDGING CONTINUES THROUGH THE U.P. TODAY THROUGH
TONIGHT, WITH MOSTLY CLEAR SKIES CONTINUING OVER THE AREA FOR MOST
OF THE TIME. THE ONLY TWO EXCEPTIONS ARE AS FOLLOWS: FIRST, SOME LOW-
LEVEL STRATUS AND PATCHY FOG BEING SEEN EARLY THIS MORNING. WHILE
SATELLITE AND WEBCAM IMAGERY IS JUST SHOWING LOW-LEVEL STRATUS FOR
NOW, WITH TEMPERATURES COOLING TOWARDS THE DEWPOINT EARLY THIS
MORNING, A RINSE-AND-REPEAT OF PATCHY FOG DEVELOPING OVER THE
INTERIOR AREAS (LIKE WHAT HAPPENED THE PREVIOUS COUPLE OF NIGHTS) IS
EXPECTED; SOME OF THE FOG COULD BE DENSE IN SPOTS. THE SECOND TIME
IS THIS AFTERNOON WHEN ENOUGH INSTABILITY DEVELOPS FOR SOME POP-UP
SHOWERS AND STORMS TO FORM, MAINLY OVER THE INTERIOR WEST (BUT ALSO
UP TO ~20% IN THE CENTRAL AND EAST AS WELL). WHILE WE COULD SEE SOME
HEAVY DOWNPOURS DURING A 'CORE DUMP' OF THE CONVECTIVE CELLS, NO
SEVERE WEATHER IS EXPECTED GIVEN THE LACK OF WIND SHEAR WITH HEIGHT
TODAY. THE MOSTLY SUNNY SKIES ARE EXPECTED TO LET TEMPERATURES RISE
INTO THE MID 70S TO AROUND 80 FOR A HIGH THIS AFTERNOON; MEANWHILE,
MOSTLY CLEAR SKIES TONIGHT SHOULD LET THE LOWS DROP DOWN INTO THE
LOWER 50S IN THE INTERIOR AREAS.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 337 AM EDT SUN AUG 31 2025
AN EXPANSIVE MID-UPPER LEVEL RIDGE CONTINUES TO STRETCH ACROSS THE
UPPER GREAT LAKES LABOR DAY TO AT LEAST TUESDAY. WITH 1020-1025MB
RIDGING OVER THE REGION THANKS TO A SURFACE HIGH SLOWLY STRETCHING
EASTWARD THROUGH THE GREAT LAKES INTO NEW ENGLAND, MOSTLY DRY
CONDITIONS ARE EXPECTED IN UPPER MICHIGAN. THE EXCEPTION TO THIS IS
LABOR DAY AFTERNOON, HOWEVER, AS A WEAK RETROGRADING VORT MAX
ALONGSIDE DAYTIME INSTABILITY GROWS TO ~1000J/KG, POTENTIALLY
YIELDING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE
LAKE BREEZE BOUNDARIES OF NORTH-CENTRAL AND WESTERN UPPER MICHIGAN.
DEEP LAYER SHEAR OVERALL LOOKS TO BE WEAK, SO STRONG OR SEVERE
STORMS ARE NOT ANTICIPATED SHOULD CONVECTION DEVELOP. STEADY 850MB
TEMPS OF 11-13C LABOR DAY AND TUESDAY WILL PRODUCE TEMPERATURES IN
THE MID TO UPPER 70S FOR MOST OF THE REGION. ALTHOUGH INCREASING
CLOUDS ON TUESDAY MAY RESULT IN HIGHS ONLY PEAKING IN THE LOW 70S IN
SOME LOCATIONS ACROSS THE WEST HALF. OVERNIGHT LOWS MONDAY NIGHT
WILL FALL INTO THE MID TO UPPER 50S NEAR THE LAKESHORES AND IN THE
KEWEENAW AND THEN TO NEAR 50F AWAY FROM THE LAKESHORES.
A PRONOUNCED UPPER LEVEL LOW IS EXPECTED TO DIVE SOUTHEAST THROUGH
MANITOBA AND ONTARIO LATE TUESDAY AND WEDNESDAY. 0Z AND 12Z
DETERMINISTIC GUIDANCE SUGGESTS THIS FEATURE WILL PARK OVER THE
UPPER GREAT LAKES WEDNESDAY NIGHT INTO THURSDAY AS IT TAKES ON A
NEGATIVE TILT, THEN LIFT NORTH AND EAST INTO HUDSON BAY THROUGH
FRIDAY NIGHT. THERE'S MORE AMBIGUITY IN THE SURFACE FEATURES, BUT
THE OVERALL CONSENSUS IS A DEEPENING LOW WILL DEVELOP ALONG A
DESCENDING COLD FRONT LATE TUESDAY. THE LOW, OR A SECONDARY SURFACE
LOW, WILL MOVE THROUGH OR NEAR UPPER MICHIGAN/LAKE SUPERIOR
WEDNESDAY OR WEDNESDAY NIGHT BEFORE BEING PUSHED NORTHWARD WEDNESDAY
NIGHT, POTENTIALLY RETROGRADING THURSDAY OVER NORTHERN ONTARIO, THEN
FINALLY EXITING NORTHEAST INTO HUDSON BAY FRIDAY NIGHT. DESPITE
BEING 4+ DAYS OUT, THIS GENERAL EVOLUTION IS HANDLED WELL BY THE
DETERMINISTIC AND ENSEMBLE GUIDANCE SUITES. THIS INCLUDES THE COLD
FRONT MOVING THROUGH UPPER MICHIGAN WEDNESDAY, RESULTING IN A LARGE
SWATH OF PRECIP SPREADING ACROSS THE AREA AHEAD OF THE BOUNDARY, AND
THE STRONGER WIND SIGNAL FOR THE KEWEENAW, WHICH MAY RESULT IN 30-40
MPH WIND GUSTS WEDNESDAY. ADDITIONALLY, MODEL RUN TO RUN CONSISTENCY
INCLUDES A SURGE OF COOLER AIR FILLING IN BEHIND THE FRONT,
RESULTING IN BELOW NORMAL TEMPERATURES TO FINISH OFF THE WORK WEEK.
EXACTLY WHERE THE COLDEST AIR ENDS UP IS STILL A QUESTION, BUT THE
GENERAL IDEA IS FOR 850MB TEMPS TO FALL TO +1 TO -3C. THIS WILL
YIELD DAYTIME HIGHS IN THE 50S OR LOW 60S AND OVERNIGHT LOWS IN THE
40S BY THE LAKES AND 30S INTERIOR. SUSPECT FROST COULD BE A CONCERN
TOWARD THE LATTER HALF OF THE WEEK, ALTHOUGH THE COOLER TEMPS ALOFT,
CONTINUED CYCLONIC MID-LEVEL FLOW, POTENTIAL FOR A SECONDARY SURFACE
TROUGH, AND LAKE EFFECT/ENHANCED RAIN, MAY WORK AGAINST SIGNIFICANT
OVERNIGHT COOLING IN SOME LOCATIONS.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 702 AM EDT SUN AUG 31 2025
VFR CONDITIONS LOOK TO DOMINATE THE TAF SITES THROUGHOUT THE PERIOD,
ALTHOUGH SOME PATCHY FOG COULD SHOW UP LATE TONIGHT OVER IWD AND SAW
(LESS THAN 50%). IN ADDITION, WE COULD SEE SOME ISOLATED SHOWERS AND
STORMS OVER THE TERMINALS BY THIS AFTERNOON. HOWEVER, GIVEN THAT THE
GREATEST CHANCES ARE IN THE WESTERN INTERIOR (UP TO 30%) AND THERE
IS ONLY AROUND A 20% CHANCE AT THE TERMINALS THIS AFTERNOON, NO
MENTIONS OF SHOWERS OR STORMS ARE IN THE TAFS AT THIS TIME. WINDS
STAY LIGHT THROUGHOUT THE PERIOD AS HIGH PRESSURE RIDGING STILL
REMAINS OVERHEAD.
MARINE
ISSUED AT 337 AM EDT SUN AUG 31 2025
HIGH PRESSURE RIDGING OVER THE REGION WILL, OVERALL, RESULT IN WINDS
BELOW 20KTS FOR A MAJORITY OF THE PERIOD THROUGH TUESDAY MORNING. BY
AFTERNOON ON TUESDAY, INCREASING PRESSURE GRADIENT WILL ALLOW FOR
INCREASING SOUTHWESTERLY WINDS ACROSS THE WESTERN AND NORTHERN
PORTIONS TO BUILD TO NEAR 20KTS. A COLD FRONT WILL MOVE MOVE THROUGH
THE REGION LATE TUESDAY/TUESDAY NIGHT INTO WEDNESDAY. BEHIND THE
FRONT, WINDS WILL QUICKLY BECOME NORTHWEST AND INCREASE AS COOLER
AIR BUILDS OVER LAKE SUPERIOR. GUIDANCE CONTINUES TO SUGGEST THE
POTENTIAL FOR GALES WEDNESDAY. LATEST ENSEMBLE GUIDANCE PACKAGES
VARY, BUT GENERALLY SUGGEST 20-40% CHANCE OF NNW OR NW GALES TUESDAY
NIGHT AND WEDNESDAY. HIGHEST PROBABILITIES ARE LOCATED WEST OF THE
KEWEENAW BETWEEN THE PENINSULA AND ISLE ROYALE AND LESSER AMOUNTS
NORTHEAST AND EAST OF THE KEWEENAW PENINSULA. NORTHWEST TO WESTERLY
FLOW WILL PERSIST OVER THE LAKE FOR THE REMAINDER OF THE WEEK,
SLOWLY FALLING BELOW 20KTS BY LATE FRIDAY.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...TAP
LONG TERM...JTP/TAP
AVIATION...TAP
MARINE...JTP/TAP
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