677
FXUS63 KDTX 031925
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
325 PM EDT THU SEP 3 2026
KEY MESSAGES
- A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR PARTS OF SE MI
UNTIL 7 PM. DAMAGING WIND GUSTS OF 60 TO 75 MPH AND TORRENTIAL
RAINFALL WILL BE THE MAIN THREATS, BUT POTENTIAL ALSO EXISTS FOR
LARGE HAIL AND TORNADOES.
- ADDITIONAL SHOWERS AND THUNDERSTORMS ARE FORECAST OVERNIGHT INTO
FRIDAY MORNING WITH POTENTIAL FOR ANOTHER ROUND LATE FRIDAY
AFTERNOON OR EVENING. ISOLATED STORMS MAY BE STRONG TO SEVERE.
- MORE SEASONABLE TEMPERATURES AND LOWER HUMIDITY ARE SLATED TO
RETURN THIS WEEKEND.
DISCUSSION
AN ORGANIZED MCS PROMPTED SEVERE THUNDERSTORM WATCH 648 WHICH
REMAINS IN EFFECT UNTIL 7PM. THIS COMPLEX IS TRACKING SOUTHEAST
ALONG A STALLED FRONTAL BOUNDARY NORTH OF A SUBTROPICAL AIR MASS.
SFC DEW POINTS SOUTH OF THE BOUNDARY SIT IN THE LOWER TO MID 70S,
WITH STEEP MID-LEVEL LAPSE RATES FUELING 2000 TO 3000 J/KG OF
SBCAPE. 35 TO 40 KNOTS OF EFFECTIVE SHEAR HAS BEEN MORE THAN
SUFFICIENT FOR BOWING SEGMENTS AND TRANSIENT EMBEDDED SUPERCELLULAR
STRUCTURES. A FEW STRONGER UPDRAFTS WILL HAVE THE POTENTIAL TO
PRODUCE LARGE HAIL, BUT THE CURRENT STORM MODE FAVORS WIND GUSTS OF
60 TO 75 MPH AS THE PRIMARY THREAT. A TORNADO OR TWO ALSO CAN'T BE
RULED OUT, ESPECIALLY WHERE ANY SEGMENTS DEVIATE S TO SSE TO
CAPITALIZE ON ENHANCED SRH THAT EXISTS NEAR METRO DETROIT.
HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE A THREAT THROUGH THE
EVENT AS PWAT SITS 2 INCHES AND A DEEP WARM CLOUD LAYER DEPTH TO 12-
13 KFT SUPPORTS EFFICIENT RAINFALL PROCESSES. WHILE MOST CONVECTION
HAS BEEN RELATIVELY PROGRESSIVE WHICH LIMITS RESIDENCE TIME OF
HEAVIER RATES, THE ENVIRONMENT SUPPORTS RATES OF 1 TO 2 INCHES PER
HOUR. CORFIDI VECTOR MAGNITUDE WEAKENS TO 10 KT SUGGESTING POTENTIAL
FOR BACKBUILDING AND TRAINING CONVECTION THAT MAY PRODUCE POCKETS OF
RAINFALL IN EXCESS OF 2 INCHES WITHIN A FEW HOURS. IF THIS OCCURS
OVER URBAN AREAS AND/OR LOCATIONS THAT HAVE RECEIVED HEAVY RAIN IN
THE PAST 24 HOURS, FLOODING WILL BE A CONCERN. AFTER THE COMPLEX
EXITS, A PERIOD OF SUBSIDENCE SUPPORTS A LULL THROUGH THE LATE
EVENING WITH POTENTIAL FOR FOG DEVELOPMENT OVERNIGHT.
THE NEXT SHORTWAVE SPILLS OVER THE UPSTREAM RIDGE AXIS OVERNIGHT
BEFORE PASSING OVER LOWER MI BETWEEN 09Z AND 18Z FRIDAY. THIS WAVE
PULLS THE NEARBY RESERVOIR OF HIGHER THETA-E BACK NE AND TOWARD THE
AREA, TIGHTENING THE INSTABILITY GRADIENT IN PLACE. THIS OFFERS A
FAVORED CORRIDOR FOR NOCTURNAL CONVECTION TO GO UPSCALE AND TRACK
ESE THROUGH THE EARLY TO MID MORNING, WITH A VEERING LLJ SUPPLYING A
FEED OF SUBTROPICAL MOISTURE INTO THE ELEVATED FRONTAL BOUNDARY.
SHOULD AN ORGANIZED COLD POOL CAPABLE OF OVERCOMING DEVELOPING CIN
EMERGE UPSTREAM, AVAILABLE HI-RES ML GUIDANCE DOES SUPPORT POTENTIAL
FOR ISOLATED TO SCATTERED STRONG TO SEVERE WIND GUSTS. GIVEN
UNFAVORABLE DIURNAL TIMING AND LIMITED SURFACE-BASED INSTABILITY,
THE FAVORED SCENARIO IS FOR A WEAKENING TREND AND RELATIVELY MUTED
SEVERE POTENTIAL. THE ENVIRONMENT REMAINS SUPPORTIVE OF LOCALIZED
TORRENTIAL RAINFALL WITH ANY CONVECTION OVERNIGHT INTO FRIDAY
MORNING.
THE FRONTAL ZONE MIGRATES SLIGHTLY SOUTHWARD ON FRIDAY, ITS
PLACEMENT AND THE SUBSEQUENT ORIENTATION OF THE INSTABILITY AXIS
DICTATING WHERE ADDITIONAL CONVECTION MAY BECOME FAVORED BY FRIDAY
AFTERNOON AND EVENING. A MAJORITY OF CAMS PLACE THIS CORRIDOR ACROSS
WESTERN LOWER MI, INTERSECTING AREAS AS FAR NORTH AS M-59. A SIMILAR
ENVIRONMENT IN PLACE OFFERS POTENTIAL FOR ANOTHER ROUND OF STRONG TO
SEVERE STORMS IF CONVECTION MATERIALIZES. THE SWODY2 HIGHLIGHTS A
MARGINAL RISK FOR SEVERE WEATHER TOMORROW WITH SUPPORT FROM HI-RES
ML GUIDANCE.
THE UPPER AIR PATTERN EVOLVES INTO A LARGE SCALE OMEGA BLOCK BY
SATURDAY, LIKELY HOLDING IN PLACE THROUGH THE WEEKEND WITH AN
AMPLIFIED RIDGE EXTENDING FROM TEXAS INTO THE NORTHERN PLAINS. OUR
PLACEMENT WITHIN THE NORTHWEST FLOW DOWNSTREAM OF THE RIDGE AXIS
KEEPS SOME POTENTIAL FOR SHOWERS/STORMS IN THE SOUTH ON SATURDAY,
BUT EXPANSIVE HIGH PRESSURE IS THEN SHOWN TO DOMINATE THE GREAT
LAKES BY THE LATTER HALF OF THE WEEKEND AND INTO THE EARLY WORK
WEEK. THIS WILL BRING THE RETURN OF A MORE SEASONABLE AIR MASS WITH
LOWER HUMIDITY.
MARINE
A STALLED FRONTAL BOUNDARY REMAINS DRAPED ACROSS THE REGION THROUGH
THIS EVENING OFFERING POTENTIAL FOR ADDITIONAL SEVERE WEATHER,
PARTICULARLY FROM THE ST. CLAIR RIVER DOWN TO WESTERN LAKE ERIE.
PREVAILING WINDS AND WAVES STAY BELOW THRESHOLD CRITERIA AS THE
GRADIENT REMAINS WEAK, BUT THE VERY UNSTABLE/MUGGY AIR MASS FAVORS
RAPID DEVELOPMENT OF STRONG TO SEVERE STORMS. SUCH STORMS WILL BE
CAPABLE OF GUSTS IN EXCESS OF 40 KNOTS AND/OR HAIL IN EXCESS OF 0.75
INCHES. MWSS AND SMWS WILL CONTINUED TO BE USED TO ADDRESS SHORT-
TERM LOCAL WATERCRAFT CONCERNS. HI-RES MODELS INDICATE THE WATERWAYS
SHOULD BEGIN TO STABILIZE BY APPROXIMATELY 00Z THIS EVENING. A LULL
IN ACTIVITY IS EXPECTED FOR PART OF THE OVERNIGHT PERIOD WITH WINDS
BECOMING LIGHT AND VARIABLE, IF NOT WEAKLY EASTERLY. A LOW
CONFIDENCE FORECAST CONTINUES INTO FRIDAY WITH ADDITIONAL ROUNDS OF
CONVECTION LIKELY FOR PORTIONS OF THE CENTRAL GREAT LAKES. THE FIRST
ROUND OF STORMS COULD REACH SAGINAW BAY AS EARLY AS 10Z FRIDAY,
FOLLOWED BY A SECONDARY ROUND FURTHER SOUTH FRIDAY EVENING. NO LONG-
FUSED HEADLINE CONCERNS EXPECTED THROUGH THE WEEKEND ONCE THE RIDGE
OVER CENTRAL CONUS EVENTUALLY DISLODGES. GUSTS SHOULD REMAIN JUST
BELOW SMALL CRAFT ADVISORY CRITERIA SATURDAY, ALBEIT WITH INCREASING
WAVE ENERGY GIVEN ONSHORE FLOW. DRIER WEATHER IS FORECAST FOR
SATURDAY AND SUNDAY.
HYDROLOGY
A MATURE THUNDERSTORM COMPLEX IS TRACKING SOUTHEASTWARD ACROSS THE
AREA THIS AFTERNOON. A SUBTROPICAL AIR MASS IN PLACE ALLOWS FOR
TORRENTIAL RAINFALL RATES OF OVER 1 INCH PER HOUR, BUT RELATIVELY
BRIEF RESIDENCE TIME OF THESE RATES HAS MITIGATED A MORE WIDESPREAD
FLOODING THREAT THUS FAR. THERE IS THE POTENTIAL FOR SOME TRAINING
OR BACKBUILDING OF STORMS THIS AFTERNOON WHICH WOULD RESULT IN
POCKETS OF AMOUNTS IN EXCESS OF 2 INCHES. THIS WOULD SUPPORT A
LOCALIZED FLOODING THREAT ESPECIALLY IF THIS OCCURS OVER ANY URBAN
AREAS OR LOCATIONS THAT RECEIVED HEAVY RAIN ALREADY IN THE PAST 24
HOURS. THERE IS A SIGNAL FOR ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS TO DEVELOP OVERNIGHT INTO FRIDAY MORNING, WHICH WILL
BE CAPABLE OF PRODUCING UP TO AN ADDITIONAL 1 TO 2 INCHES OF
RAINFALL FOR LOCALIZED AREAS.
PREV DISCUSSION
ISSUED AT 153 PM EDT THU SEP 3 2026
AVIATION...
A HOT AND HUMID AIRMASS HAS LED TO BLOSSOMING CONVECTION ALONG A
CONVERGENCE AXIS THAT STRETCHES FROM ROUGHLY LUDINGTON TO DETROIT.
THIS BOUNDARY HAS AND WILL CONTINUE TO BE THE FOCUS FOR
THUNDERSTORMS TODAY AND TONIGHT, WITH A THUNDERSTORM COMPLEX ONGOING
NEAR KMBS AT ISSUANCE. THIS FEATURE WILL RIDE THE BOUNDARY SOUTHEAST
AND IMPACT MOST TERMINAL SITES BETWEEN NOW AND ROUGHLY 22Z THIS
EVENING. LIGHT AND VARIABLE FLOW PERSISTS OUTSIDE OF THUNDERSTORM
ACTIVITY, BUT QUICKLY RAMPS UP TO 40-50 KNOTS IN THUNDERSTORMS WITH
ADDITIONAL HAZARDS INCLUDING LARGE HAIL AND AN ISOLATED TORNADO
THREAT. ONCE CONVECTIVE ACTIVITY CLEARS OUT THIS EVENING, A CLEARING
TREND IS EXPECTED OVERNIGHT AND, DEPENDING ON THE EXTENT OF THIS
CLEARING, COULD RESULT IN LOW STRATUS/FOG DEVELOPMENT TONIGHT-FRIDAY
MORNING GIVEN THE MOIST BOUNDARY LAYER. THUNDERSTORM ACTIVITY
CONTINUES INTO FRIDAY IN WHICH SEVERE WEATHER CONTINUES TO BE
POSSIBLE.
D21/DTW CONVECTION... A THUNDERSTORM COMPLEX CURRENTLY NEAR KMBS
WILL TRACK SOUTHEAST ALONG A CONVERGENCE AXIS THROUGH THE AFTERNOON,
BRINGING POTENTIAL FOR SEVERE THUNDERSTORMS TO ALL TERMINALS BETWEEN
NOW AND 22Z. DAMAGING WINDS IN EXCESS OF 50 KNOTS ARE THE MAIN
THREAT, BUT LARGE HAIL IN EXCESS OF 1 INCH AND AN ISOLATED TORNADO
ARE POSSIBLE AS WELL.
DTW THRESHOLD PROBABILITIES...
* LOW FOR CEILING 5000 FT OR LESS EARLY THIS AFTERNOON. MODERATE
AFTER 00Z TONIGHT.
* HIGH FOR THUNDERSTORMS BETWEEN NOW AND 22Z THIS EVENING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...TF
MARINE.......KGK
HYDROLOGY....TF
AVIATION.....MV
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