093
FXUS63 KDTX 121744
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
144 PM EDT TUE AUG 12 2025
KEY MESSAGES
- HOT AND MUGGY CONDITIONS AGAIN TODAY WITH HEATING INDICES IN THE
LOW TO MID-90S.
- POTENTIAL EXISTS FOR SHOWERS AND THUNDERSTORMS TO DEVELOP THROUGH
TONIGHT.
- THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY
RAINFALL. IN ADDITION, ISOLATED WIND GUSTS OF 50 TO 60 MPH WILL BE
POSSIBLE THIS AFTERNOON AND EVENING.
- HIGH PRESSURE BRINGS NEAR NORMAL TEMPERATURES AND LESS HUMID
CONDITIONS TO CLOSE OUT THE WORK WEEK.
AVIATION
ORGANIZED MOISTURE ADVECTION AHEAD OF A DEEP CANADIAN MIDLEVEL
TROUGH WILL LEAD TO SHOWER AND THUNDERSTORM ACTIVITY ACROSS
SOUTHEAST MICHIGAN TODAY AND TONIGHT. CURRENTLY OBSERVING A
COMPOSITE OUTFLOW JUST NORTH OF METRO DETROIT THAT IS CURRENTLY
FUNNELING SHOWER ACTIVITY OVER THE I 69 CORRIDOR. SCT-BKN LOW VFR
CUMULUS ACTIVITY HAS DEVELOPED TO THE SOUTH OF THIS BOUNDARY WITHIN
A PRISTINE DIURNALLY HEATED AIRMASS. IFR TO OCCASIONAL VLIFR
CONDITIONS IN HEAVY RAINFALL WILL BE POSSIBLE WITH ANY THIS
AFTERNOON THROUGH 06Z TONIGHT. THERE IS UNCERTAINTY WITH MUCH
ACTIVITY WILL IMPACT THE DETROIT TERMINALS SPECIFICALLY AS THERE IS A
MODEL SIGNAL THAT SUGGESTS STORMS WILL NOT BE FAVORABLY ALIGNED TO
THE WIND SHEAR.
FOR DTW/D21 CONVECTION...THE LIKELY TIME WINDOW FOR THUNDERSTORM
ACTIVITY IS 23Z AND 03Z THIS EVENING.
THRESHOLD PROBABILITIES...
* LOW FOR THUNDERSTORMS THIS AFTERNOON. MODERATE FOR THIS EVENING.
PREV DISCUSSION
ISSUED AT 324 AM EDT TUE AUG 12 2025
DISCUSSION...
RENEWED LOW-MID LEVEL THETA-E ADVECTION UNDERWAY LOCALLY EARLY THIS
MORNING, SOLIDIFIED BY INCREASING DEPTH TO SOUTH TO SOUTHWEST FLOW
WITHIN THE IMMEDIATE DOWNSTREAM FLANK OF BROADER UPPER MIDWEST
TROUGHING. THIS PROCESS IN COMBINATION WITH LOW LEVEL JET SUPPORT
SUSTAINING A SMALL CORRIDOR OF CONVECTION ACROSS SOUTHWEST LOWER MI.
THIS ACTIVITY MAY CONTINUE TO CAPITALIZE ON THE UNDERLYING MOIST AND
WEAKLY UNSTABLE ENVIRONMENT, WITH CURRENT TRAJECTORY OFFERING SOME
POTENTIAL FOR A PERIOD OF ELEVATED CONVECTION OVER MAINLY AREAS
NORTH OF I-69 YET THIS MORNING. LITTLE EVIDENCE PER RADAR/SATELLITE
TRENDS TO SUGGEST A GREATER NOCTURNAL RESPONSE WILL MATERIALIZE TO
THE SOUTH THIS MORNING, WITH THE ADVECTIVE PROCESS ALONE PROVING
INADEQUATE.
RESIDENT MOIST AND DIURNALLY DESTABILIZING ENVIRONMENT WILL REMAIN
CONDUCIVE TO SOME DEGREE OF CONVECTIVE DEVELOPMENT ACROSS THE
AFTERNOON AND EVENING PERIODS FROM A THERMODYNAMIC PERSPECTIVE, BUT
STILL CARRIES CONSIDERABLE UNCERTAINTY ON POTENTIAL SCALE AND TIMING
OWING TO LESS DEFINED SOURCES OF GREATER FORCED ASCENT. A SUBSET OF
THE HI RES SOLUTION SPACE KEY ON ONGOING ACTIVITY NOW SPILLING INTO
WESTERN ILLINOIS, WITH THE POSSIBILITY FOR THE GOVERNING
CONVECTIVELY ENHANCED VORT MAX TO MAINTAIN AN NE/ENE TRAJECTORY AND
ARRIVE LOCALLY BY EARLY-MID AFTERNOON. AREAS GENERALLY NORTH OF M-59
POSITIONED MORE FAVORABLY IN THIS INSTANCE. FROM THERE INTO THE
EVENING, CONVECTIVE INITIATION REMAINS PLAUSIBLE ESSENTIALLY
ANYWHERE THROUGHOUT LOWER MICHIGAN STRETCHING BACK INTO SOUTHERN
LAKE MI/CHICAGO AREA AS POCKETS OF CONVERGENCE ENGAGE THE EXISTING
INSTABILITY GRADIENT. HEAVY RAINFALL RISK CERTAINLY EXISTS GIVEN
EFFICIENT RAIN RATE POTENTIAL WITHIN A DEEP MOIST LAYER, BUT PERHAPS
WITH THE OVERALL RAIN DURATION AT ANY ONE LOCATION MORE LIMITED WITH
JUST ENOUGH STEERING FLOW IN THE COLUMN TO KEEP CONVECTIVE CLUSTERS
MORE PROGRESSIVE. AREAS NORTH OF M-59 APPEAR MORE SUSCEPTIBLE TO
MULTIPLE ROUNDS OF ACTIVITY UNDER THE CURRENT SETUP, HIGHLIGHTING A
HIGHER PROBABILITY FOR A LOCALIZED HIGHER QPF STRIP IN EXCESS OF
0.75-1" SOMEWHERE WITHIN THIS CORRIDOR. ISOLATED OCCURRENCES OF
STRONG WIND GUSTS ALSO PLAUSIBLE WITHIN ANY DEEPER PRECIPITATION
LOADED CORES. ENOUGH POTENTIAL EXISTS TO WARRANT AN UPGRADE IN THE
DAY 1 SPC OUTLOOK TO A MARGINAL RISK. FORECAST WILL OFFER A SLIGHT
INCREASE IN PROJECTED HIGHS ACROSS THE SOUTH, ACKNOWLEDGING A
GREATER LIKELIHOOD FOR LIMITED TO NO CONVECTIVE DISRUPTION TO THE
HEATING CYCLE, AFFORDING ANOTHER DAY PUSHING TO/ABOVE 90 DEGREES.
THIS PLACES PEAK HEAT INDEX VALUES AGAIN IN THE MID 90S FOR METRO
DETROIT.
GREATER HEIGHT FALLS COMMENCING ACROSS THE NORTHERN GREAT LAKES WILL
DRAW A COLD FRONT ACROSS LOWER MICHIGAN OVERNIGHT INTO EARLY
WEDNESDAY. INHERENT FRONTAL CONVERGENCE MAINTAINS LOWER END PRECIP
CHANCES THROUGH THIS PERIOD, WITH PACE OF THE FRONTAL PASSAGE AND
TRAILING DRY AIR ADVECTION DICTATING WHETHER THIS POTENTIAL LAGS
INTO THE DAYLIGHT PERIOD WEDNESDAY FOR SOUTHERN SECTIONS. OTHERWISE,
TEMPERATURES TRENDING COOLER RELATIVE TO RECENT DAYS, WITH A MORE
NOTEWORTHY DOWNTURN IN HUMIDITY FOR THE LATE WEEK PERIOD AS HIGH
PRESSURE TAKES CONTROL. HEAT AND HUMIDITY WILL RETURN NEXT WEEKEND
WITH UPPER RIDGING GAINING INFLUENCE.
MARINE...
STRONG LOW PRESSURE TRACKS ACROSS NORTHERN ONTARIO TODAY AND
TONIGHT, DRAGGING A COLD FRONT ACROSS THE GREAT LAKES LATE THIS
AFTERNOON-EVENING. SHOWER AND THUNDERSTORM CHANCES EXIST THROUGHOUT
THE DAY AS THE FRONT APPROACHES AND THE AIRMASS REMAINS
WARM/UNSTABLE, BUT NOTABLY SHIFTS TO A MORE LINEAR STORM MODE AS THE
FRONT DRAWS CLOSER IN THE EVENING. GUSTY WINDS IN EXCESS OF 40 KNOTS
WILL BE POSSIBLE IN ADDITION TO HEAVY RAINFALL AND FREQUENT
LIGHTNING. SHOWERS AND ELEVATED STORMS LINGER THROUGH WEDNESDAY
MORNING BEFORE THE FRONT FULLY CLEARS EAST AND WINDS SHIFT TO THE
NORTHWEST. BY THIS POINT, UPPER LEVEL TROUGHING AND HIGH PRESSURE
BUILD IN WHICH ALLOWS COOLER AND DRIER CONDITIONS TO DEVELOP FOR THE
BACK HALF OF THE WORK WEEK. FLOW SHIFTS ONSHORE LATE IN THE WEEK AS
WINDS VEER AROUND THE HIGH PRESSURE SYSTEM, WHICH WILL ELEVATED WAVE
HEIGHTS ESPECIALLY FOR SAGINAW BAY AND THE THUMB REGION.
HYDROLOGY...
A HIGH LIKELIHOOD EXISTS FOR SHOWERS AND THUNDERSTORMS TO DEVELOP
THROUGH TONIGHT WITHIN A HOT AND HUMID ENVIRONMENT. A VERY MOIST
ENVIRONMENT WILL CREATE FAVORABLE CONDITIONS FOR LOCALLY HEAVY
RAINFALL, WITH RAINFALL RATES POTENTIALLY IN EXCESS OF 2"/HR UNDER
THE STRONGEST STORMS. BASIN AVERAGE RAINFALL RATES BETWEEN ONE HALF
AND ONE INCH ARE POSSIBLE, WITH LOCALLY HIGHER AMOUNTS IN EXCESS OF
ONE INCH WHERE SLOW MOVING OR TRAINING CELLS DEVELOP. LOCALIZED
FLOODING OF URBAN, LOW-LYING AND POOR DRAINAGE AREAS ALONG WITH
RISES IN AREA RIVERS WILL BE POSSIBLE.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....CB
DISCUSSION...MR
MARINE.......MV
HYDROLOGY....MR
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