418
FXUS63 KDTX 021853
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
253 PM EDT WED SEP 2 2026
KEY MESSAGES
- A HEAT ADVISORY REMAINS IN EFFECT THROUGH THE EVENING WITH HEAT
INDICES IN THE UPPER 90S TO NEAR 100 DEGREES.
- THERE IS A SLIGHT RISK FOR SEVERE WEATHER THIS AFTERNOON AND
EVENING. DAMAGING WINDS TO 70 MPH, HAIL TO 1.5 INCH, AND AN
ISOLATED TORNADO THREAT ARE ALL POSSIBLE.
- ADDITIONAL SHOWER AND THUNDERSTORM CHANCES THURSDAY AND FRIDAY.
HEAVY RAINFALL IS POSSIBLE.
DISCUSSION
HOT AND HUMID CONDITIONS CONTINUE THROUGH THE EVENING, BOOSTED BY
LOW 70S DEWPOINTS AND HIGHS IN THE LOW 90S. THIS HAS BROUGHT PEAK
HEAT INDICES ACROSS THE DETROIT METRO REGION INTO THE LOW 100S WHICH
WILL LINGER THROUGH EARLY EVENING, WHICH HAS ALSO ESTABLISHED A
ROBUST POOL OF INSTABILITY ACROSS ALL OF SE MICHIGAN. QUESTION
REMAINS HOW STRONG THE CAP IS, WHICH HAS LIMITED CONVECTION FROM
FULLY BLOSSOMING IN AN OTHERWISE FAVORABLE THERMODYNAMIC
ENVIRONMENT. OBSERVATIONAL CUES SHOW THIS CAP ERODING ACROSS THE
SAGINAW VALLEY REGION AND OTHER BOUNDARIES OUTSIDE OF THE CWA, WHILE
INBOUND MOISTURE SUGGESTS FURTHER EROSION THIS EVENING.
SWODY1 SLIGHT RISK THUS PERSISTS GIVEN THE CONDITIONALLY FAVORABLE
SEVERE ENVIRONMENT. BULK PARAMETERS ARE IMPRESSIVE, AS SPC
MESOANALYSIS REPORTS SBCAPE UP TO 4000 J/KG AND 0-6KM BULK SHEAR
OVER 40 KNOTS DUE TO A MID-LEVEL JET IMPULSE ALOFT (H5 WINDS OF 50-
55 KNOTS). THIS SHOULD BE SUPPORTIVE OF ORGANIZED MULTICELLULAR
AND/OR SUPERCELLULAR STRUCTURES AS SHEAR VECTORS ARE ORIENTED ~45
DEGREES TO THE INITIATING BOUNDARIES. LOW CONFIDENCE HOWEVER EXISTS
IN THE INITIAL DEVELOPMENT OF STORMS AND SUBSEQUENT
COVERAGE/EVOLUTION AS THERE WILL BE MULTIPLE WEAK FORCING MECHANISMS
IN PLAY. THUS, A WIDE SPECTRUM OF OUTCOMES EXPECTED ACROSS SE
MICHIGAN, WITH THE MOST BULLISH SCENARIOS PRODUCING DAMAGING WINDS
TO 70 MPH AND HAIL OVER 1.5". THESE SOLUTIONS CARRY HIGHER
CONFIDENCE FOR THE SAGINAW VALLEY/THUMB THAN THE METRO DETROIT
REGION. WHILE LOW LEVEL CURVATURE IS NOT PREVALENT ATTM, LAKE
BREEZES/ STORM OUTFLOW COULD LOCALLY AUGMENT HODOGRAPHS TO SUPPORT
AN ISOLATED TORNADO THREAT AS WELL. PROGRESSIVE STORM MOTION
GENERALLY LIMITS LONG DURATION RAINFALL CONCERNS THIS EVENING,
ALTHOUGH HEAVY DOWNPOURS ARE LIKELY.
EPISODES OF SHOWERS AND THUNDERSTORMS THEN CONTINUE OVERNIGHT
THROUGH THE END OF THE WORK WEEK, WITH LOW PREDICTABILITY IN TIMING
AND COVERAGE. THE UNSETTLED PATTERN WILL BE SUPPORTED BY A
BAROCLINIC AXIS THAT LINGERS OVER SE MICHIGAN OVER THE NEXT SEVERAL
DAYS, KEEPING PLENTY OF INSTABILITY AROUND WITHIN A SEASONABLY
HOT/HUMID AIRMASS. HIGHS THURSDAY AGAIN APPROACH 90 DEGREES WITH
HEAT INDICES PUSHING WELL INTO THE 90S TO NEAR 100 DEGREE READINGS
IN URBAN AREAS, DEPENDING ON CLOUD COVER/CONVECTIVE COVERAGE. MUCH
OF OUR SHOWER/THUNDERSTORM CHANCES WILL BE DETERMINED BY UPSTREAM
MCS DEVELOPMENT AND THE PROPAGATION OF THESE SYSTEMS INTO SE
MICHIGAN AS RIDGING BUILDS OVER CENTRAL CONUS. MOST LIKELY CADENCE
FOR THESE STORMS (BASED ON PATTERN RECOGNITION) IS A WAVE OF
NOCTURNAL/EARLY MORNING CONVECTION FOLLOWED BY REINVIGORATION OF
STORMS LATER IN THE DAY WITH THE PEAK HEATING CYCLE THAT REPEATS
UNTIL THE FRONT FULLY CLEARS SOUTH OF THE STATE LINE THIS WEEKEND.
THE BUILDING RIDGE CAUSES MID-LEVEL WINDS TO VEER FROM WEST TO
NORTHWEST BY END OF WEEK, DRAWING IN COOLER AIR THAT ALTERS BOTH LOW
AND MID-LEVEL THERMAL PROFILES. ULTIMATELY THIS CAUSES THE SEVERE
THREAT TO DECREASE FRIDAY-THE WEEKEND, DESPITE SHOWER AND STORM
CHANCES REMAINING IN THE FORECAST. A COOLER PATTERN IS EXPECTED THIS
WEEKEND, WITH HIGHS FALLING INTO THE UPPER 70S.
MARINE
WINDS AND WAVES REMAIN BELOW THRESHOLD CRITERIA ACROSS THE CENTRAL
GREAT LAKES, ASIDE FROM A FEW THUNDERSTORMS PASSING THROUGH A VERY
MUGGY AIR MASS THIS AFTERNOON AND EVENING. GRADIENT WINDS WILL SHIFT
FROM SOUTHWEST TO NORTHWEST ONCE A WEAK COLD FRONT DROPS
SOUTHEASTWARD THROUGH REGION. CONVECTIVE CHANCES DECREASE A BIT
OVERNIGHT WITHIN THE WAKE OF THE SLOWING FRONT, AND WINDS COULD
BRIEFLY TREND TOWARDS CALM. A LOW CONFIDENCE FORECAST PERSIST
THROUGH THE END OF THE WEEK AND EARLY THIS WEEKEND AS A RIDGE OVER
CENTRAL CONUS REMAINS QUASI-STATIONARY. THIS OFFERS SEVERAL
ADDITIONAL OPPORTUNITIES FOR PERIODS OF SHOWERS AND THUNDERSTORMS.
MWS AND SMW HEADLINES WILL CONTINUED TO BE USED TO ADDRESS SHORT-
TERM LOCAL WATERCRAFT CONCERNS. NO LONG-FUSED HEADLINE CONCERNS
THROUGH THE WEEKEND, ALTHOUGH AREAS OF DENSE FOG COULD BECOME AN
ISSUE AGAIN LATE TONIGHT INTO THURSDAY MORNING FOR PORTIONS OF THE
WATERWAYS.
HYDROLOGY
FIRST ROUND OF SHOWERS AND THUNDERSTORMS IS ONGOING ACROSS THE
SAGINAW VALLEY AND THUMB REGIONS, WITH CHANCES CONTINUING OVERNIGHT.
THE HOT AND HUMID AIRMASS WILL SUPPORT HEAVY DOWNPOURS WITHIN MOST
THUNDERSTORMS, ALTHOUGH PROGRESSIVE NATURE OF STORMS LIMITS
DURATION. ANY STRONG THUNDERSTORM WILL HAVE THE POTENTIAL TO PRODUCE
A QUICK 1-2 INCHES OF RAIN, WHICH CAN LEAD TO LOCALIZED MINOR
FLOODING OF ROADS AND POOR-DRAINAGE AREAS. THERE ARE CURRENTLY NO
INDICATIONS OF TRAINING STORMS, THOUGH MORE EXTENSIVE FLOODING WOULD
BECOME A CONCERN IF A MATURE MCS DEVELOPS OR STORMS REPEATEDLY
IMPACT THE SAME AREA.
PREV DISCUSSION
ISSUED AT 104 PM EDT WED SEP 2 2026
AVIATION...
FRONTAL BOUNDARY SAGGING INTO SOUTHERN LOWER MI OFFERS CHANCES FOR
THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON (NORTH) INTO THE
EVENING (SOUTH). VERY LOW CONFIDENCE FORECAST IN POTENTIAL
THUNDERSTORM COVERAGE PARTICULARLY TOWARDS THE SOUTHERN TERMINALS
WHERE SOME DEGREE OF CAPPING IS IN PLACE. FOR THESE SITES, HAVE ONLY
ADDED PROB30 MENTIONS TO HIGHLIGHT THE WINDOW OF 'BEST' POTENTIAL.
WHILE THERE IS HIGHER CONFIDENCE IN THE NORTH FOR SCATTERED
THUNDERSTORMS, WHETHER THESE IMPACT MBS/FNT OR ARE FOCUSED MORE
TOWARDS THE THUMB IS THE MAIN STICKING POINT. AS SUCH, MAINTAINED
INHERITED PROB30S AND WILL AMEND AS NEEDED ONCE STORMS COALESCE.
WHILE THE HUMID AIRMASS OFFERS A SHOT AT SOME SPOTTY OVERNIGHT
CONVECTION, HIGH-RES MODELS HAVE TRENDED DRIER TONIGHT.
D21/DTW CONVECTION...THE BEST CHANCE FOR THUNDERSTORMS IS NORTH OF
DTW TOWARD THE NORTHERN FRINGE OF D21 THIS AFTERNOON, BUT
THUNDERSTORM CHANCES MAY DEVELOP THIS EVENING BETWEEN 21-00Z.
DTW THRESHOLD PROBABILITIES...
* LOW FOR CEILING 5000 FT OR LESS THIS AFTERNOON-EVENING.
* LOW FOR THUNDERSTORMS THIS EVENING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ068>070-075-076-
082-083.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...MV
MARINE.......KGK
HYDROLOGY....MV
AVIATION.....KDK
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page