848
FXUS63 KMQT 261950
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
350 PM EDT SAT JUL 26 2025
KEY MESSAGES
- A SLIGHT RISK (CATEGORY 2 OF 5) OF SEVERE WEATHER (PRIMARILY
DAMAGING WINDS) IS IN EFFECT FOR THE WESTERN UP SUNDAY AS POTENTIAL
EXISTS FOR ONE OR MULTIPLE ROUNDS OF STRONG TO SEVERE THUNDERSTORMS.
- WARMER THAN NORMAL TEMPERATURES AND MUGGY DEW POINTS PREVAIL
THROUGH MONDAY. SUNDAY AND MONDAY HAVE A ~10% CHANCE OF HEAT INDICES
OF 100+ IN THE INTERIOR WEST.
- COOLER THAN NORMAL TEMPERATURES AND DRIER CONDITIONS ARE EXPECTED
BY THE MIDDLE OF NEXT WEEK.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 349 PM EDT SAT JUL 26 2025
GOES-EAST IMAGERY SHOWS MOSTLY CLEAR SKIES OVER THE UP THIS
MORNING AS THE UP REMAINS ON THE NORTHWEST PERIPHERY OF A 500MB
RIDGE OVER THE SOUTHEAST. A PAIR OF SHORTWAVES ARE RESOLVED BY
THE RAP ANALYSIS, ONE LIFTING INTO NORTHWEST ONTARIO AND ONE
DISSIPATING OVER SOUTHERN WI/NORTHERN IL. THE FIRST SHORTWAVE
DOES CARRY ABOUT A 30 PERCENT CHANCE OF BRINGING SOME SHOWERS
AND PERHAPS A RUMBLE OF THUNDER TO ISLE ROYALE TODAY BUT CHANCES
OF PRECIP ON THE MAINLAND UP ARE 15 PERCENT OR LESS. THE MAIN
WEATHER IMPACTS TODAY ARE GOING TO BE THE REMNANT CANADA
WILDFIRE SMOKE (WHICH HRRR-SMOKE SHOWS DISSIPATING/VENTING
THROUGHOUT THE DAY) AND THE HEAT. THE HREF SHOWS SOME POCKETS OF
THE WESTERN UP (PARTICULARLY IN DOWNSLOPING AREAS WITH
PERSISTENT SW FLOW) REACHING HEAT INDEX VALUES OF 90+ DEGREES.
EXPECT HIGH TEMPERATURES ELSEWHERE IN THE UP TO BE AROUND THE 85
DEGREE MARK. LITTLE RELIEF WILL COME OVERNIGHT WITH MID 60S FOR
LOW TEMPERATURES (AND EVEN LOWS NEAR 70 FOR AREAS THAT
DOWNSLOPE TO LAKE SUPERIOR).
SUNDAY, A BOOM OR BUST THUNDERSTORM SET UP WILL BE IN PLACE AS A
MORE ROBUST SHORTWAVE APPROACHES THE REGION. MUCH OF THE DETAILS
ABOUT THUNDERSTORM DEVELOPMENT WILL BE DEPENDENT ON UPSTREAM
CONVECTION IN MINNESOTA, WITH ONLY A FEW MODELS (MOST NOTABLY THE
RRFS AND ONE OR TWO WRF MEMBERS OF THE HREF) SHOWING NOTABLE
DISCRETE CELLULAR CONVECTION FIRING AHEAD OF MESOSCALE CONVECTIVE
SYSTEMS. SHOULD DISCRETE CONVECTION OCCUR THOUGH, THE CAMS THAT DO
HAVE SUPERCELL POTENTIAL AS ENHANCING FLOW ALOFT MAKES FOR ENOUGH
SHEAR TO SUPPORT STRONG CONVECTION. WITH ANOTHER HOT AND HUMID DAY
IN THE FORECAST (HIGHS NEAR 90, DEW POINTS NEAR 70), LAPSE RATES
WILL BE STEEP AND PLENTIFUL CAPE IS PRESENT, WITH HREF MEAN MUCAPE
CLIMBING TO NEAR 3000 J/KG AND ENSEMBLE MAX SBCAPE IN THE 3500-4500
J/KG RANGE. ONE COMPLICATING FACTOR COULD BE THE LAKE BREEZE, WHICH
SOME CAMS SHOW WITH THE POTENTIAL TO ACT AS AN ADDITIONAL LIFTING
MECHANISM AS WINDS WONT QUITE BE AS STRONG AS TODAY. ALL OF THE
INGREDIENTS SEEM TO BE IN PLAY, SO FORCING WILL BE THE VARIABLE
FACTOR THAT ANSWERS THE QUESTION ABOUT WHAT CONVECTION WILL LOOK
LIKE TOMORROW. THERE SEEM TO BE THREE SCENARIOS EMERGING: THE
"ISOLATED AFTERNOON CONVECTION AHEAD OF A BIGGER LINE IN THE
EVENING" CAMP AS DESCRIBED ABOVE, THE "TWO ROUNDS OF LINEAR
CONVECTION" CAMP (12Z HRRR AND WRF ARW), BUT ALSO A "NOTHING
HAPPENS" CAMP WITH EVERYTHING STAYING TO THE NORTH OR SOUTH (12Z
CANADIAN HI-RES, CLIMATOLOGY, VARIOUS ELEMENTS AND EARLIER RUNS OF
OF OTHER CAMS). WITH THE CEILING OF IMPACTS HIGH (DAMAGING WIND IN
PARTICULAR LOOKS TO BE A THREAT WITH ANY BOWING SEGMENTS OF LINEAR
CONVECTION), BUT THE FLOOR OF "NOTHING HAPPENS" BEING PARTICULARLY
LOW, THE SPC HAS A SLIGHT RISK (CATEGORY 2 OF 5) FOR THE WEST HALF
OF THE UP AND A MARGINAL RISK (CATEGORY 1 OF 5) FOR THE EAST HALF.
WHILE TRAINING CONVECTION IS NOT A PARTICULARLY HIGH RISK, PLENTIFUL
MOISTURE THAT'S WELL-FORCED COULD CREATE TORRENTIAL RAINFALL AND
SOIL MOISTURE IS STILL ELEVATED OVER PORTIONS OF THE NORTH AND WEST
UP, SO THE WPC MAINTAINS A MARGINAL RISK (CATEGORY 1 OF 4) FOR
RAINFALL IN EXCESS OF FLASH FLOOD GUIDANCE.
LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/
ISSUED AT 349 PM EDT SAT JUL 26 2025
BY 00Z MONDAY, THE UPPER AIR PATTERN CONSISTS OF A 500MB RIDGE OVER
MUCH OF THE SOUTHERN US, WEAK RIDGING OVER THE US ROCKIES, AND A
STRONG CUTOFF LOW ON THE WEST COAST OF HUDSON BAY. FLOW WILL BE
QUASI-ZONAL ACROSS THE UP MONDAY WITH SUBTLE SHORTWAVE IMPULSES
KEEPING SHOWER AND THUNDERSTORM CHANCES IN THE FORECAST MONDAY. WARM
WEATHER CONTINUES FOR MONDAY WITH THE NBM SHOWING A HIGH OF 90 FOR
IRON MOUNTAIN AND DEW POINTS REMAINING NEAR 70 FOR MUCH OF THE UP.
WHILE THE LREF SHOWS CHANCES OF TRIPLE DIGIT HEAT INDEX BEING LESS
THAN 10 PERCENT, THE CHANCE OF 95+ HEAT INDEX IS 30-40 PERCENT FOR
THE SOUTH-CENTRAL. DESPITE THE HEAT AND HUMIDITY, WHAT THUNDERSTORMS
DO OCCUR ARE NOT EXPECTED TO BE SEVERE DUE TO UNCERTAINTY IN THE
AVAILABLE FORCING. IF FORCING DOES BECOME AVAILABLE THOUGH,
PLENTIFUL SHEAR STILL EXISTS AND THE LREF DOES SHOW UP TO 2500 J/KG
OF SBCAPE STILL LINGERING IN THE SOUTH-CENTRAL. THERE'S EVEN A
SLIGHT CHANCE (AROUND 20 PERCENT) OF A DIURNALLY DRIVEN THUNDERSTORM
FOR THE SOUTH-CENTRAL UP ON TUESDAY ACCORDING TO THE NBM.
FOLLOWING THAT, RIDGING RETREATING TO THE SOUTHERN PLAINS WITH THE
HUDSON LOW DEEPENING AND ROCKIES RIDGING BUILDING WILL LEAD TO
NORTHWEST FLOW ALOFT. THIS SETS UP COOLER NW FLOW ALOFT OVER THE UP
WHICH WILL LEAD TO TEMPERATURES NEAR OR BELOW NORMAL (HIGHS IN THE
MID TO LOWER 70S, LOWS AROUND 50) TUESDAY THROUGH THE END OF THE
WEEK. BEING UPSTREAM OF RIDGING WILL LEAD TO DRY WEATHER FOR THE
MOST PART, THOUGH THE COOLER TEMPERATURES AND SURFACE MOISTURE THAT
JUST WONT QUIT WILL KEEP RHS FROM FALLING TOO FAR (NBM MINIMUM RHS
ALL ABOVE 35 PERCENT).
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 130 PM EDT SAT JUL 26 2025
VFR IS ONGOING AT ALL SITES AND IS EXPECTED TO REMAIN SO FOR THIS
PERIOD. THE ONLY EXCEPTION WILL BE IF FG CAN FORM OVERNIGHT AT SAW
AND/OR CMX, WHICH CURRENTLY HAS ABOUT A 30 PERCENT CHANCE OF
DROPPING TO MVFR OR BELOW, SO A TEMPO GROUP HAS BEEN ADDED TO EACH
SITE. TSRA ASSOCIATED WITH THUNDERSTORM COMPLEXES UPSTREAM ARE A BIT
DIFFICULT TO DETERMINE TIMING AND LOCATION, THOUGH CURRENTLY THEY
ARE EXPECTED TO HOLD OFF UNTIL AFTER 18Z SUNDAY AT ALL SITES.
HOWEVER, THIS COULD CHANGE IF SHORT-RANGE MODELS COME TO AGREEMENT
ON THE MORNING TO EARLY AFTERNOON DEVELOPMENT OF STORMS.
MARINE
ISSUED AT 349 PM EDT SAT JUL 26 2025
LIGHT WINDS OF 20 KNOTS OR LESS DOMINATE THE REST OF THIS WEEK
THROUGH EARLY NEXT WEEK AS HIGH PRESSURE RIDGING GENERALLY REMAINS
OVER THE REGION FOR THE NEXT SEVERAL DAYS, SAVE FOR A SHORTWAVE
TROUGH EMBEDDED WITHIN THE RIDGE PASSING THROUGH THE REGION SUNDAY.
THIS SHORTWAVE WILL BRING THUNDERSTORMS TO THE LAKE, AND A FEW MAY
BRING SEVERE WEATHER (UP TO 30 PERCENT CHANCE) AND FREQUENT
LIGHTNING. THUNDERSTORM CHANCES WILL LINGER INTO MONDAY, BUT
PLACEMENT, TIMING, AND INTENSITY OF SUCH STORMS IS UNCERTAIN.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...GS
LONG TERM...GS
AVIATION...GS
MARINE...GS
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