608  
FXUS63 KDTX 261021  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
621 AM EDT SAT JUL 26 2025  
   
KEY MESSAGES
 
 
- MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY  
INTO TONIGHT. A FEW STORMS COULD GENERATE DAMAGING WIND GUSTS  
HOWEVER TORRENTIAL RAINFALL AND LOCALIZED AREAS OF FLOODING IS THE  
PRIMARY HAZARD WITH STORMS TODAY.  
 
- HEAT AND HUMIDITY BUILD SUNDAY AND MONDAY AS HIGH TEMPERATURES  
RETURN TO THE LOWER 90S WITH HEAT INDEX NEAR 100 THROUGH EARLY NEXT  
WEEK.  
 

 
   
AVIATION
 
 
AN ONGOING INFLUX OF DEEP LAYER MOISTURE IN ADVANCE OF UPSTREAM  
SHORT WAVE IMPULSES WILL RESULT IN INCREASING COVERAGE OF SHOWERS  
DURING THE LATE MORNING INTO THE AFTERNOON. THE ASCENT TIED TO A  
LITTLE MORE AMPLIFIED WAVE WILL BE STRONGEST DURING THE AFTERNOON,  
COINCIDING WITH PEAK DAYTIME INSTABILITY. THIS WILL BE THE PERIOD  
WHERE THUNDERSTORM POTENTIAL WILL BE GREATEST. FORCED ASCENT MAY  
LINGER INTO TONIGHT ACROSS FAR SOUTHERN LOWER MI, ALONG A MID LEVEL  
MOISTURE AND INSTABILITY GRADIENT. THIS MAY PROVIDE ANOTHER ROUND OF  
CONVECTION TO THE METRO DETROIT TERMINALS LATE THIS EVENING INTO THE  
EARLY PORTION OF THE OVERNIGHT. CLOUD BASES ARE LIKELY TO REMAIN  
HIGHLY VARIABLE THROUGH THE DAY. MVFR AND IFR BASED STRATUS WHICH  
HAS BEEN DEVELOPING ACROSS THE REGION EARLY THIS MORNING SHOULD  
EXPERIENCE SOME INCREASE IN THE CLOUD BASES WITH DIURNAL MIXING.  
 
FOR DTW/D21 CONVECTION...WHILE PRECISE TIMING STILL CARRIES SOME  
UNCERTAINTY, THERE CONTINUES TO BE THE POTENTIAL FOR EITHER  
SCATTERED CONVECTION OR A CLUSTER OF CONVECTION TO IMPACT THE  
AIRSPACE FROM MID AFTERNOON INTO THE EARLY EVENING HOURS.  
 
THRESHOLD PROBABILITIES...  
 
* MODERATE IN CEILINGS AOB 5000 FEET TODAY AND TONIGHT.  
 
* MODERATE IN THUNDERSTORMS THIS AFTERNOON AND EVENING. LOW TONIGHT.  
 

 
   
PREV DISCUSSION
 
 
ISSUED AT 303 AM EDT SAT JUL 26 2025  
 
DISCUSSION...  
 
ACTIVE PATTERN CONTINUES TODAY AS A SERIES OF CONVECTIVELY AUGMENTED  
SHORTWAVES ARE SET TO STREAM INTO SOUTHERN LOWER MI FROM THE  
MIDWEST. IN THE NEAR TERM, THE STALLED FRONTAL BOUNDARY OVER  
LENAWEE/MONROE CONTINUES TO SUPPORT SQUATTERED (THUNDER)SHOWERS FOR  
AREAS SOUTH OF I-96 EARLY THIS MORNING. THIS ACTIVITY SHIFTS  
NORTHWARD OVER THE COURSE OF THE MORNING AS THE FIRST SHORTWAVE  
IMPULSE OVER NORTHERN IL AT PRESS TIME BEGINS TO PUSH INTO MI  
FORCING THE FRONTAL BOUNDARY BACK NORTH AS A WARM FRONT. MODEST  
DEVELOPING LLJ (~25-35KTS) BEHIND THE FRONT LEADS TO RAPID MOISTURE  
TRANSPORT INTO SE MI AS SURFACE DEWPOINTS QUICKLY REACH THE LOWER  
70S BY LATE MORNING- CLOSER TO MID 70S LIKELY IN THE SOUTH. IN TERMS  
OF PW CLIMATOLOGY, THIS AIRMASS IS NEAR/ABOVE THE DAILY RECORD AS 2-  
2.25" VALUES OVERSPREAD THE REGION.  
 
LEAD SHORTWAVE AND ACCOMPANYING SHOWERS BEGIN TO VACATE TO OUR EAST  
LATE MORNING/MIDDAY AS THE SECOND, STRONGER MID-LEVEL WAVE  
(CURRENTLY OVER NORTHERN MO/KS AT PRESS TIME) ARRIVES OVER THE  
STATE. A SIZABLE SUBSET OF CAMS HAVE BEGUN CONVERGING ON THIS WAVE  
PROVIDING THE GREATEST STORM COVERAGE OF THE DAY AS IT TRACKS ACROSS  
SE MI. HOWEVER THESE SOLUTIONS STILL VARY QUITE A BIT WITH THE  
WAVE'S TIMING REACHING THE WESTERNMOST CWA AREAS, RANGING FROM AS  
EARLY AS 14-15Z TO AS LATE AS 18-19Z, OWING TO DIFFERENCES IN  
HANDLING THE ONGOING CONVECTIVE INFLUENCE/MODIFICATION. THE LATER  
THE ARRIVAL WINDOW, THE MORE DIURNAL DESTABILIZATION IS ABLE TO  
OCCUR TO PUSH SBCAPE VALUES TOWARD 1500 J/KG SUPPORTING BETTER STORM  
COVERAGE AS WELL AS MORE RIGOROUS UPDRAFTS. SHEAR ISN'T PARTICULARLY  
IMPRESSIVE THOUGH THE LLJ DOES SUPPORT 0-6KM BULK VALUES NEAR 30KTS  
FOCUSED TOWARDS THE OHIO BORDER. THESE SOUTHERN AREAS (SOUTH OF M-  
59) ARE UNDER A DAY 1 MARGINAL RISK FROM SPC MAINLY FOR DAMAGING  
WIND GUSTS. THAT SAID, MAIN HAZARD WITH CONVECTION WILL BE  
TORRENTIAL RAINFALL AND FLOODING POTENTIAL GIVEN THE MOISTURE-RICH  
AIRMASS COMBINED WITH WARM CLOUD LAYERS BETWEEN 13-15KFT. THIS  
SECONDARY WAVE SHIFTS EAST OF THE AREA DURING THE EARLY EVENING  
TIMEFRAME LIKEWISE SHIFTING THE WIDER SPREAD CONVECTION TO OUR EAST  
WITH LINGERING SHOWERS/STORMS TURNING MORE SCATTERED IN NATURE.  
 
FINALLY A THIRD TRAILING MCV AUGMENTED SHORTWAVE THEN IS SET TO  
SLIDE ACROSS THE REGION LATE EVENING. THE FAVORED TRACK IS  
NEAR/ALONG THE IN/OH/MI BORDER HOWEVER SOME SOLUTIONS LIKE THE NAM  
NEST ADVERTISE SLIGHTLY FARTHER NORTH OVER SOUTHERN LOWER MI. THE  
EXACT TRACK WILL DETERMINE THE NORTHWARD EXTENT OF ADDITIONAL RAIN-  
AS IT CURRENTLY STANDS I-69 LOOKS TO BE THE NORTHERN EDGE. THIS  
PORTION OF THE EVENT HOWEVER CARRIES HIGH UNCERTAINTY AND OVERALL LOW  
PREDICTABILITY AS HOW MUCH CONVECTION IS EVEN ABLE TO DEVELOP WITH  
THIS WAVE IS HIGHLY DEPENDENT ON THE PROGRESSION AND ROBUSTNESS OF  
EARLIER DAY SHOWERS/STORMS UNDER TO THE FIRST TWO SHORTWAVES.  
 
DRIER CONDITIONS TAKE HOLD BY SUNDAY MORNING AS WEAK SURFACE HIGH  
PRESSURE ESTABLISHES ITSELF OVER THE CENTRAL GREAT LAKES. FIRST HALF  
OF THE NEW WEEK IS DOMINATED BY A BROAD MID-UPPER RIDGING OVER THE  
CONUS EAST OF THE ROCKIES. SE MI RESIDES ON THE NORTHERN EDGE OF THE  
HEAT DOME BRINGING A RENEWED MULTI-DAY PERIOD OF HIGHS IN THE UPPER  
80S AND 90S, DEWPOINTS ABOVE 70F, AND HEAT INDICES WELL INTO THE 90S  
TO NEAR 100F. CAVEAT IS BEING ON THE EDGE OF THE RIDGE OPENS THE  
DOOR FOR RIDGE-RUNNING MCS'S TO TRACK NEAR OR OVER THE AREA  
POTENTIALLY INFLUENCING BOTH ACTUAL AND FEELS-LIEK TEMPS.  
 
MARINE...  
 
WEAK HIGH PRESSURE IS NOW OFF TO THE EAST IN ONTARIO, WITH LIGHT  
WINDS RANGING FROM SW TO E WITHIN THE DIFFUSE PRESSURE PATTERN LEFT  
BEHIND. MAIN FOCUS FOR TODAY IS THE NORTHWARD SHIFT OF THE WARM  
FRONT, WHICH SHIFTS WINDS TO THE SOUTHWEST AND DRAWS WARM/UNSTABLE  
AIR BACK INTO LOWER MICHIGAN. SHOWER AND THUNDERSTORM COVERAGE IS  
EXPECTED TO INCREASE AND EXPAND NORTHWARD THROUGH THE DAY AS SEVERAL  
DISTURBANCES RIPPLE ALONG THE FRONTAL ZONE. A FEW STRONG TO SEVERE  
STORMS WILL BE POSSIBLE THIS AFTERNOON-EVENING, WITH THE PRIMARY  
CONCERN BEING WIND GUSTS IN EXCESS OF 40 KNOTS AND ISOLATED LARGE  
HAIL TO AN INCH. THE SEVERE THREAT WANES AFTER MIDNIGHT, BUT HEAVY  
RAINFALL MAY CONTINUE THROUGH SUNDAY MORNING UNTIL HIGH PRESSURE  
USHERS IN A DRIER AIRMASS BRIEFLY FOR SUNDAY. PERIODS OF SHOWERS AND  
STORMS CONTINUE INTO EARLY NEXT WEEK FOLLOWED BY A PATTERN SHIFT MID-  
WEEK AS CANADIAN HIGH PRESSURE FILLS IN FROM THE NORTHWEST.  
 
HYDROLOGY...  
 
THE STALLED FRONT LIFTS BACK NORTH TODAY AS WARM FRONT USHERING HOT  
AND HUMID CONDITIONS BACK OVER THE ENTIRE REGION. THE ANOMALOUSLY  
MOIST AIRMASS OVERSPREADS THE REGION WHILE STILL CARRYING PW AROUND  
2" IN ADDITION TO WARM CLOUD DEPTHS SUPPORTING EFFICIENT RAINFALL  
RATES. A SERIES OF WAVES AUGMENTED BY ONGOING CONVECTION OVER THE  
PLAINS ARE SET TO SLIDE OVER SOUTHERN LOWER MI THROUGHOUT THE DAY.  
SCATTERED SHOWERS/STORMS ARE POSSIBLE THIS MORNING THROUGH THE LATE  
EVENING WITH GREATEST COVERAGE LOOKING TO OCCUR DURING THE AFTERNOON-  
EARLY EVENING PERIOD. OVERALL PREDICTABILITY FOR TIMING, LOCATION,  
AND DURATION OF STORMS ARE LOW OWING TO THE COMPLEX SET-UP HOWEVER  
CONFIDENCE IS HIGH FOR TORRENTIAL RAINFALL THREATS UNDER ANY STORMS  
TODAY DUE TO THIS MOISTURE-LADEN AIRMASS. RAINFALL RATES IN EXCESS  
OF 2"/HR ARE LIKELY UNDER THE STRONGEST STORMS (EVEN WEAKER STORMS  
WILL BE CAPABLE OF RATES AT OR ABOVE 1"/HR). LOCALIZED FLOODING IS  
EXPECTED ESPECIALLY IN URBAN AND LOW LYING/FLOOD PRONE AREAS. MORE  
IMPACTFUL FLOODING IS POSSIBLE SHOULD STORMS TRAIN OVER THE SAME  
LOCATIONS.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LAKE HURON...NONE.  
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  

 
 

 
 
AVIATION.....SC  
DISCUSSION...KDK  
MARINE.......MV  
HYDROLOGY....KDK  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
 
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