710
FXUS63 KMQT 091841
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
241 PM EDT SAT AUG 9 2025
KEY MESSAGES
- THERE IS A SLIGHT RISK (CATEGORY 2 OF 5) OF SEVERE WEATHER,
PRIMARILY DAMAGING WINDS, FOR THE SOUTH-CENTRAL UP THIS
AFTERNOON AND EVENING.
- CHANCES OF SHOWERS AND THUNDERSTORMS LINGER THROUGH TUESDAY.
- HIGH TEMPERATURES REMAIN ABOVE-NORMAL TO NEAR-NORMAL
THROUGHOUT THE NEXT WEEK.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 139 PM EDT SAT AUG 9 2025
MORNING RAP ANALYSIS SHOWS A 1001MB LOW PRESSURE CENTERED OVER LAKE
WINNIPEG THAT HAS A SURFACE TROUGH DRAPED FROM ITS EASTERN SIDE DOWN
THROUGH THE WESTERN UP DOWN INTO THE MISSISSIPPI RIVER VALLEY. EARLY
MORNING RADAR AND SATELLITE TRENDS HAVE STRUGGLED TO MAINTAIN
CONVECTION, WHICH IS SUSPECTED TO BE A COMBINATION OF SUBSTANTIAL
LOW-TO-MID LEVEL CIN AND THE NATURE OF STORMS BEING OUTFLOW-
DOMINATED WITH NOT MUCH SHEAR PRESENT. TO THE FIRST POINT, SURFACE
DESTABILIZATION LOOKS TO BE OCCURRING IN THE CENTRAL UP PER THE RAP
WITH UP TO 2500 J/KG OF SBCAPE. HOWEVER, WITH THE NOCTURNAL LLJ
DIMINISHING, THE ALREADY POOR SHEAR IS NOT HELPING THE SECOND POINT.
STILL, WITH THE SURFACE TROUGH PROVIDING FORCING AND SURFACE DEW
POINTS IN THE MID 70S ALREADY, THE POTENTIAL FOR A VIGOROUS UPDRAFT,
EVEN IF BRIEF, IS TOO HIGH TO IGNORE. MOST OF THE MORNING CAM RUNS
HAVE BEEN TOO SLOW WITH CONVECTION AND MANY SHOWED THUNDERSTORMS
EARLY IN THE RUN OVER THE UP THAT WERE MUCH STRONGER THAN THEY
ACTUALLY WERE. THAT BEING SAID, ONCE THE ONGOING LINE OF STORMS
APPROACHES THE EASTERN UP BY AROUND 21Z THIS AFTERNOON, SOME CAMS
(NAMELY THE HRRR AND WRF ARW) SHOW A SECOND ROUND OF THUNDERSTORMS
THREATENING THE CENTRAL UP IN THE 22-00Z TIMEFRAME. THIS SECOND
ROUND, THE INSTABILITY AND SHEAR WILL BE FLIPPED ON THEIR HEADS,
WITH THE BETTER SHEAR ARRIVING WITH 0-3KM SRH VALUES JUMPING UP
AROUND 150, BUT THE INSTABILITY WILL BE WANING SOMEWHAT, WITH ONLY
AROUND 1000 J/KG EXPECTED. GIVEN THE HGZ IS STILL AROUND 500MB, HAIL
CONTINUES TO NOT BE THE PRIMARY THREAT, BUT DAMAGING WINDS AND
FREQUENT LIGHTNING WILL BE IN PLAY. SOME 1"/HR RAINFALL RATES MAY BE
OBSERVED, BUT STORM MOTION APPEARS TO KEEP MOST FLASH-FLOODING
CONCERNS AT BAY. THE CEILING OF IMPACTS IS HIGH ENOUGH TO WARRANT
THE SPC ISSUING A SLIGHT RISK (CATEGORY 2 OF 5) FOR SEVERE WEATHER
(PRIMARILY DAMAGING WIND) AND THE WPC ISSUING A MARGINAL RISK
(CATEGORY 1 OF 4) FOR EXCESSIVE RAINFALL.
THE HRRR STILL CAN'T GET ENOUGH OF CONVECTION TONIGHT THOUGH, AS IT
HAS YET ANOTHER ROUND OF ISOLATED CONVECTION IN THE 00Z-04Z RANGE
TONIGHT, THOUGH SUPPORT FOR THAT SOLUTION IS MOSTLY IGNORED BY THE
REST OF THE 12Z CAM SUITE. SCATTERED LIGHT RAIN SHOWERS ARE THEN
FORECAST INTO SUNDAY, WHERE THE CAMS ARE SOMEWHAT SPLIT ON THE
POTENTIAL FOR DIURNAL CONVECTION IN THE INTERIOR UP. SHOULD
CONVECTION OCCUR, THE CONTINUED PRESENCE OF A WARM, MOIST SURFACE
AIRMASS WILL HELP INSTABILITY VALUES OF AROUND 500-1000 J/KG PERSIST
AND HODOGRAPHS DO SHOW BETTER SHEAR PROFILES. GIVEN THE LACK OF
FORCING, CONFIDENCE REMAINS LOW.
THE OTHER HAZARD IN THE SHORT TERM IS THE HEAT RISK. GIVEN EXTENSIVE
CLOUD COVER, TEMPERATURES ARE NOT GOING TO GET OUT OF CONTROL TODAY
(HIGHS IN THE MID 80S), BUT THE AFOREMENTIONED DEW POINTS IN THE 70S
WILL MAKE IT FEEL MUGGY AND MAKE COOLING OFF MORE CHALLENGING. SOME,
BUT NOT MUCH, RELIEF IS EXPECTED OVERNIGHT AS LOWS FALL INTO THE
60S, BUT HIGHS IN THE 80S WITH DEW POINTS IN THE 70S RETURN FOR
SUNDAY. HEAT INDICES IN THE 90S WILL BE POSSIBLE, ESPECIALLY IN
AREAS ALONG LAKE SUPERIOR WHERE OCCASIONALLY GUSTY SOUTHERLY WINDS
WILL DOWNSLOPE AND WARM FURTHER THAN HIGHER ELEVATION COUNTERPARTS
FURTHER INLAND.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
ISSUED AT 239 PM EDT SAT AUG 9 2025
BY 00Z MONDAY, THE CUTOFF LOW FORCING THIS PERIOD OF DISTURBED
WEATHER WILL HAVE WEAKENED SIGNIFICANTLY AS IT LIFTS INTO THE
HUDSON BAY AREA. LONGWAVE TROUGHING WILL KEEP WARM, MOIST AIR
OVER THE AREA AND THUS KEEPING HIGH TEMPERATURES MONDAY IN THE
LOW 80S DESPITE FALLING 500MB HEIGHTS WITH LONGWAVE TROUGHING
EXTENDS FROM THE ROCKIES INTO THE GREAT LAKES. REMNANT SURFACE
TROUGHING WILL KEEP POPS IN THE FORECAST FOR MONDAY IN THE EAST
HALF, THOUGH THE CHANCES OF RAINFALL RATES OVER A QUARTER INCH
PER 6 HOURS IS ONLY AROUND 15 PERCENT PER THE LREF.
ATTENTION TURNS TO A SHORTWAVE TROUGH RAPIDLY MOVING SOUTHEAST FROM
THE NORTHWEST TERRITORIES AT 00Z MONDAY TO JUST NORTHWEST OF
THE UPPER GREAT LAKES BASIN BY 18Z TUESDAY. THE LAST 24 HOURS OF
ENSEMBLE GUIDANCE HAVE GRANTED MUCH IMPROVED AGREEMENT ON THE
PLACEMENT OF THE PARENT TROUGH, THOUGH THE RESULTING SURFACE LOW
WILL BE FAR ENOUGH NORTH THAT PRECIPITATION OVER THE UP MAY
NEED A BOOST FROM DIURNAL INSTABILITY OR PERHAPS A LAKE BREEZE
BOUNDARY. INSTABILITY LOOKS OK, AROUND 500 J/KG, AND WHILE BULK
SFC-500MB SHEAR VALUES AROUND 40 KT LOOK IMPRESSIVE, HODOGRAPHS
LOOK UNIDIRECTIONAL FOR THE MOST PART. WINDS ALOFT SHIFTING OUT
OF THE NORTHWEST WILL BE A LITTLE LATE TO PROVIDE MUCH RELIEF
FROM ABOVE AVERAGE TEMPERATURES AS TUESDAY'S HIGHS WILL BE
AROUND 80 PER THE NBM, THOUGH OVERNIGHT LOWS IN THE MID 50S IN
THE INTERIOR WILL BE A WELCOME RETURN TO NEAR-NORMAL FOR THIS
TIME OF YEAR.
QUASI-ZONAL FLOW ALOFT IS THEN EXPECTED FOR THE MIDWEEK PERIOD,
KEEPING PRIMARILY DRY WEATHER IN THE FORECAST WITH NEAR- TO SLIGHTLY
ABOVE-NORMAL TEMPERATURES, THOUGH THIS PATTERN MAY ALLOW FOR SOME
LAKE BREEZE SHOWERS IF THE CONDITIONS LINE UP CORRECTLY. MODEL
SPREAD THEN INCREASES FOR THE FRIDAY AND BEYOND PERIOD AS THE
VARIOUS GLOBAL DETERMINISTIC AND ENSEMBLE SUITES DISAGREE ON THE
BREAKDOWN OF SOUTHERN US RIDGING AND THE ARRIVAL OF A CUTOFF LOW
OVER THE CANADIAN PRAIRIE. LOTS OF VARIANCE IN THE RESULTING WEATHER
IS SEEN IN THE ENSEMBLES, THOUGH ON A CONCEPTUAL LEVEL, WARM
SOUTHWESTERLY FLOW SEEMS PROBABLE TO RETURN WITH CHANCES OF SHOWERS
AND THUNDERSTORMS PROBABLY DEPENDENT ON UPSTREAM CONVECTIVE
DEVELOPMENT OVER THE UPPER MIDWEST.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 139 PM EDT SAT AUG 9 2025
VFR CONDITIONS ARE OBSERVED AT ALL SITES WITH ALL SITES AFFECTED BY
SHOWERS AND THUNDERSTORMS RECENTLY. WHILE PRECIP WILL CLEAR OUT OF
IWD AND CMX THIS EVENING, FURTHER WAVES OF PRECIPITATION WILL AFFECT
SAW INTO THIS EVENING AND POTENTIALLY SUNDAY. LOW LEVEL HUMIDITY
WILL BRING WITH IT THE THREAT OF FG FORMATION AT ALL SITES, WITH
GUIDANCE SUGGESTING AROUND A 25 PERCENT CHANCE OF VISIBILITY
REDUCTIONS (AND AROUND 10 PERCENT CHANCE OF LIFR CONDITIONS).
HOWEVER, GIVEN PERSISTENT SOUTH TO SOUTHWEST WINDS GUSTING OVER 10
KT EXPECTED THROUGHOUT THE NIGHT, WILL LEAVE FG MENTION OUT OF THIS
TAF.
MARINE
ISSUED AT 139 PM EDT SAT AUG 9 2025
WIND GUSTS TO 20 KT WILL BE PRIMARILY LIMITED TO THE IMMEDIATE
VICINITY OF THUNDERSTORMS THAT WILL CONTINUE TO BE OVER THE EAST
HALF OF THE LAKE THROUGH TONIGHT, WITH THE FAR EASTERN END OF THE
LAKE RETAINING THUNDERSTORM CHANCES THROUGH SUNDAY. TUESDAY WILL
ALSO BRING CHANCES OF WIND GUSTS UP TO 25 KT OUT OF THE SOUTHWEST AS
A DISTURBANCE PASSES OVER THE LAKE. WITH THE ONGOING HOT AND HUMID
CONDITIONS FOLLOWING SHOWERS, CHANCES OF DENSE FOG INCREASE THROUGH
SUNDAY, THOUGH THE ONGOING SOUTHERLY TO SOUTHWESTERLY WINDS ARE
KEEPING FOG MOSTLY AWAY FOR THE TIME BEING.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
BEACH HAZARDS STATEMENT UNTIL 10 PM EDT THIS EVENING FOR
MIZ014.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...GS
LONG TERM...GS
AVIATION...GS
MARINE...GS
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