654
FXUS63 KMQT 230007
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
807 PM EDT TUE JUL 22 2025
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS ARE EXPECTED LATE TONIGHT INTO EARLY
WEDNESDAY, WITH ADDITIONAL ROUNDS THROUGH THE DAY WEDNESDAY.
- STORMS LATE TONIGHT AND WEDNESDAY COULD PRODUCE HEAVY RAIN,
HAIL, AND STRONG TO DAMAGING WINDS. THERE IS A SLIGHT CHANCE
(AT LEAST 15%) OF EXCEEDING FLASH FLOOD GUIDANCE AND SEVERE
WEATHER ACROSS MOST OF UPPER MICHIGAN.
- ADDITIONAL SHOWERS AND THUNDERSTORMS ARE POSSIBLE WEDNESDAY
NIGHT THROUGH LATE THURSDAY.
- STRONG WINDS AND LARGE WAVES WILL RESULT IN DANGEROUS SWIMMING
CONDITIONS ON LAKE MICHIGAN BEACHES OF SCHOOLCRAFT COUNTY BY
WEDNESDAY AFTERNOON.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 336 PM EDT TUE JUL 22 2025
UPPER AIR PATTERN CONSISTS OF AN EXPANSIVE 500MB RIDGE CENTERED OVER
THE US SOUTHEAST WITH TROUGHS OVER THE PACIFIC NORTHWEST, FAR
NORTHERN MANITOBA, AND LABRADOR RESPECTIVELY. EMBEDDED WITHIN THE
RIDGE IS A COMPACT SHORTWAVE OVER MINNESOTA PIVOTING TOWARDS THE
UPPER GREAT LAKES. AT THE SURFACE, THE PROGRESSION OF SURFACE
FEATURES IS A BIT COMPLEX AND NEBULOUS, AS SURFACE LOW PRESSURE ON
THE LEE SIDE OF THE ROCKIES IS EXTENDING SURFACE TROUGHING NORTHEAST
WHILE THE SURFACE LOW ASSOCIATED WITH THE NORTHERN CANADIAN TROUGH
IS EXTENDING SURFACE TROUGHING SOUTHWEST FROM THE WESTERN END OF THE
HUDSON BAY, RESULTING IN A COLD FRONT DRAPED ACROSS NORTHWEST
ONTARIO, NORTHERN MN, AND EASTERN ND. ELSEWHERE, A WARM FRONT ALSO
EXTENDS EASTWARD FROM THE HIGH PLAINS LOW, WHICH WILL ALSO SERVE TO
COMPLICATE THE AVAILABLE FORCING FOR POTENTIAL SEVERE WEATHER IN THE
SHORT TERM.
TODAY, AHEAD OF THE WARM FRONT, SUBSTANTIAL WARM AND MOIST SOUTHERLY
FLOW WILL RESULT IN A GENERAL INCREASING TREND IN MOISTURE OVER THE
UP, WITH THE NAEFS SHOWING 2+ INCH PWATS BY 12Z WEDNESDAY,
APPROACHING THE CLIMATOLOGICAL MAXIMUM FOR THIS TIME OF YEAR.
MOISTURE TRANSPORT PLOTS DO SHOW A CONNECTION TO THE SOUTH-CENTRAL
US WHICH HAS INFLUENCES FROM BOTH THE SOUTHWEST US MONSOON AND THE
GULF, THOUGH THE RAMPANT EVAPOTRANSPIRATION FROM UPSTREAM CORN BELT
STATES MAY BE EVEN MORE OF AN INFLUENCE. THE UP WONT SEE THE 80S DEW
POINTS THAT IA/SURROUNDING AREAS WILL GET, BUT THE HREF SHOWS 70+
DEW POINTS AT A 60-70% CHANCE AS SOON AS THIS AFTERNOON OVER THE
WESTERN UP AND WIDESPREAD 70+% CHANCES WEDNESDAY PM. THE LATENT
HEATING OF SUCH A MOIST AIRMASS WILL HELP SENSIBLE TEMPERATURES FROM
RACING OUT OF CONTROL, BUT MAX TEMPS IN THE MID 80S WITH THE
AFOREMENTIONED MOISTURE WILL MAKE FOR SOME HEAT INDICES IN THE 90S,
AND LITTLE OVERNIGHT RELIEF IS EXPECTED WITH LOW TEMPERATURES
GENERALLY IN THE MID 60S TO MID 70S (WARMEST SOUTH, WEST).
THIS WARM, MOIST AIRMASS WILL RESULT IN AN UNSTABLE ATMOSPHERE OVER
THE UP THE NEXT COUPLE OF DAYS. THIS AFTERNOON, THE WEST HALF OF THE
UP WILL DESTABILIZE FROM AROUND 500 J/KG (MARQUETTE, MENOMINEE
COUNTIES) TO AROUND 1750 J/KG (GOGEBIC, ONTONAGON COUNTIES).
HOWEVER, WITH NEBULOUS FORCING, THE 12Z CAM SUITE HAS MOVED AWAY
FROM CONVECTION OVER THE UP, EXCEPT FOR A FEW CAMS SHOWING
CONVECTIVE ACTIVITY OVER ISLE ROYALE AND WESTERN LAKE SUPERIOR THIS
EVENING AND OVERNIGHT PERIOD. WITH THE CONVERGENCE OF THE COLD FRONT
TO THE NORTHWEST AND THE WARM FRONT TO THE SOUTH, BETTER FORCING
WILL BE IN PLAY FOR WEDNESDAY, THOUGH MUCH OF THE DETAILS WILL
DEPEND ON VARIOUS MESOSCALE CONVECTIVE SYSTEMS/COMPLEXES/ETC, AS
SOME OF THE 00Z CAMS HAD THE UP MISSING OUT ON AT LEAST ONE OR TWO
ROUNDS OF CONVECTION WITH THINGS GOING THROUGH EITHER ONTARIO OR
WISCONSIN INSTEAD. WHEN CONVECTION HAPPENS OVER THE UP WEDNESDAY,
PLENTIFUL INSTABILITY REMAINS, WITH THE EASTERN UP SEEING THE NEAR
500 J/KG WHILE THE WESTERN UP WILL BE AROUND 1000-2000 J/KG (90TH
PERCENTILE OF THE HREF IS UP TO 2800 ALONG THE STATE LINE). BULK
SHEAR OF AROUND 30 KT AND 0-3KM SRH OF AROUND 100 M2/S2 IS
SUFFICIENT TO MAINTAIN CONVECTION. WITH PLENTY OF MOVING PARTS,
UNCERTAINTY IN THE DETAILS IS HIGH, BUT THE CEILING FOR SEVERE
WEATHER IS HIGH ENOUGH TO WARRANT A MARGINAL RISK (CATEGORY 1 OF 5)
FOR SEVERE WINDS OVER THE FAR WESTERN UP PRIOR TO 12Z WEDNESDAY AND
A WIDESPREAD SLIGHT RISK (CATEGORY 2 OF 5) FOR DAMAGING WINDS AND AN
ISOLATED TORNADO THREAT (2%, UNLIKELY BUT CANNOT ENTIRELY BE RULED
OUT) FOR THE DAYTIME HOURS OF WEDNESDAY. ANOTHER THREAT WORTH
MONITORING WILL BE THE FLASH FLOOD POTENTIAL, AS THE AFOREMENTIONED
MOIST AIR WILL LEAD TO HEAVY RAINFALL RATES WITH VIGOROUS
CONVECTION, AND SEVERAL CAMS SHOW CONVECTION EITHER TRAINING OR
MULTIPLE ROUNDS OF HEAVY RAIN, WITH DAILY HREF LPMM PLOTS SHOWING A
PLAUSIBLE WORST-CASE SCENARIO OF 4+ INCHES (THOUGH MEAN QPF SHOWS A
MORE LIKELY SCENARIO OF AROUND 1.25-1.75 INCHES). THIS POTENTIAL FOR
IMPACTFUL FLASH FLOODING HAS LED THE WPC TO ISSUE A SLIGHT RISK
(CATEGORY 2 OF 4) FOR THE UP WEDNESDAY FOR EXCESSIVE RAINFALL.
WITH GUSTY, LONG-DURATION S TO SW WINDS OCCURRING AHEAD OF THE
PRECIP, WAVE HEIGHTS ALONG THE SHORES OF LAKE MICHIGAN FROM THE
GARDEN PENINSULA TO PORT INLAND WILL SWELL TO 4-6 FT, INCREASING THE
RISK OF POTENTIALLY DEADLY RIP CURRENTS AND HAZARDOUS SWIMMING
CONDITIONS.
LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/
ISSUED AT 336 PM EDT TUE JUL 22 2025
THUNDERSTORMS WILL BE ONGOING ACROSS THE UP BY 00Z THURSDAY, THOUGH
INTENSITY SHOULD WANE AS BOTH PRIOR CONVECTION AND DECREASING
DIURNAL DESTABILIZATION CONTRIBUTE TO INSTABILITY WANING. HEAVY RAIN
WILL CONTINUE TO BE A THREAT WELL INTO THE OVERNIGHT AND INTO
THURSDAY AS THE NBM SHOWS MULTIPLE AREAS SEEING 1"/6HR RAIN RATES
WEDNESDAY NIGHT THROUGH THURSDAY AFTERNOON. EVENTUALLY LATE
THURSDAY, THE FRONTS WILL HAVE ALL PUSHED EAST AND PRECIP WILL END
FROM WEST TO EAST. THE "COLD" PART OF THE COLD FRONT IS ONLY
RELATIVE THOUGH AS NBM HIGH TEMPERATURES ON THURSDAY ARE STILL
AROUND 80, WHICH BRINGS THE UP BACK TO SEASONAL TEMPERATURES.
AS TROUGHS CONTINUE TO MARCH THROUGH CANADA, STUBBORN RIDGING WILL
REMAIN OVER THE SOUTHERN CONUS, THOUGH RETROGRADING SOMEWHAT TO BE
OVER THE SOUTHERN PLAINS INSTEAD OF THE SOUTHEAST BY THE BEGINNING
OF NEXT WEEK. WITH THE UP BEING IN AN AREA OF SLIGHTLY ANOMALOUS
500MB HEIGHTS AT THE TOP OF THE RIDGE, WARMER THAN NORMAL
TEMPERATURES CONTINUE TO PREVAIL WITH HIGHS IN THE 80S FOR THE MOST
PART AND DEW POINTS PRIMARILY IN THE 60S AS PREVAILING WINDS ADVECT
IN CORN BELT MOISTURE AND OTHER SOUTHERN US MOISTURE SOURCES AS
DESCRIBED ABOVE. RIDGE-RIDING SHORTWAVE IMPULSES WILL DRIVE
OCCASIONAL SHOWER AND THUNDERSTORM CHANCES, THOUGH THE SMALL NATURE
OF SUCH EMBEDDED WAVES MAKE DETAILS CHALLENGING TO DERIVE.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 806 PM EDT TUE JUL 22 2025
LATEST OBSERVATIONS SHOW A WEAKENING CLUSTER OF THUNDERSTORMS
PRESSING THROUGH WEST-CENTRAL LAKE SUPERIOR, WHICH WILL LIKELY
IMPACT CMX BY ~01Z AND QUICKLY PASS THROUGH THE KEWEENAW SHORTLY
AFTER. NO SEVERE WEATHER IS EXPECTED WITH THESE POSSING STORMS.
TONIGHT SHOULD REMAIN QUIET, HOWEVER, THERE IS STILL SOME
UNCERTAINTY ABOUT HOW THE TIMING OF TSRA SHAKES OUT LATER, BUT MOST
GUIDANCE AT LEAST SHOWS PRECIP IN THE MORNING HOURS OF WEDNESDAY,
AND HEAVIER SHOWERS WILL BRING MVFR TO POTENTIALLY IFR (UP TO 30
PERCENT CHANCE). WINDS THROUGHOUT THIS PERIOD WILL BE MAINLY OUT OF
THE SOUTH TO SOUTHEAST AT AROUND 5-10 KT WITH GUSTS TO 15-20 KT.
MARINE
ISSUED AT 336 PM EDT TUE JUL 22 2025
LIGHT WINDS OF GENERALLY 20 KNOTS OR LESS ARE EXPECTED TO DOMINATE
THE FORECAST, SAVE FOR SOME SOUTHERLY WINDS OF 20 TO 25 KNOTS OVER
THE EASTERN HALF OF THE LAKE THIS EVENING AND TONIGHT AS HIGH
PRESSURE BUILDS EAST OF LAKE SUPERIOR AND LOW PRESSURE OVER THE
PLAINS DEEPENS. SOME SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS
THE LAKE THIS EVENING THROUGH THURSDAY. SOME THE STORMS MAY BE
STRONG TO SEVERE, BRINGING FREQUENT LIGHTNING, ERRATIC/DAMAGING
WINDS (UP TO 30 PERCENT CHANCE), AND A WATERSPOUT CANNOT BE RULED
OUT (ABOUT A 2 PERCENT CHANCE).
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...GS
LONG TERM...GS
AVIATION...BW
MARINE...GS
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