131  
FXUS63 KDTX 141951  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
351 PM EDT THU AUG 14 2025  
   
KEY MESSAGES  
 
- HEAT AND HUMIDITY RETURN FOR THE WEEKEND WITH MAINLY DRY CONDITIONS  
TO START.  
 
- HEAT INDICES PEAK IN THE UPPER 90S SATURDAY AFTERNOON.  
 
- CHANCE OF THUNDERSTORMS LATE SATURDAY THROUGH SUNDAY WITH AN  
ISOLATED SEVERE STORM POSSIBLE.  
 
- COOLER AND A BIT LESS HUMID EARLY NEXT WEEK.  
 
 
   
DISCUSSION  
 
SPLIT-FLOW CONFIGURATION OVERHEAD FOR THE REMAINDER OF TODAY  
MAINTAINS LOW-IMPACT WEATHER ACROSS THE GREAT LAKES WITH A BRIEF  
REPRIEVE FROM THE HEAT AND HUMIDITY. BETTER LONGWAVE DYNAMICS RESIDE  
NORTH OF CONUS WHILE LIGHT ZONAL FLOW LINGERS ALOFT, LOCALLY. SPARSE  
DIURNAL CUMULUS FIELD WANES QUICKLY THIS EVENING WITH MOSTLY CLEAR  
SKIES IN STORE FOR THE OVERNIGHT HOURS. DEW POINTS IN THE LOWER 60S  
WILL KEEP LOWS IN-CHECK TONIGHT, WITH PERHAPS SOME PATCHY AREAS OF  
FOG AROUND SUNRISE.  
 
JAMES BAY SURFACE RIDGE INFLUENCE WANES FRIDAY AS THE PRESSURE  
GRADIENT RESPONDS TO UPSTREAM TROUGHING. THIS FLIPS LOWER  
TROPOSPHERIC WINDS SOUTHWESTERLY, USHERING IN MODERATING  
THERMODYNAMIC PROFILES. 850 MB TEMPERATURES CLIMB INTO UPPER TEENS  
(CELSIUS) BY FRIDAY AFTERNOON, RESULTING IN HIGH TEMPERATURES IN THE  
UPPER 80S. NO REAL PRECIPITATION CONCERNS FOR FRIDAY AS A CAPPING  
INVERSION HOLDS NEAR THE 10 KFT MARK WITH A SHALLOW SATURATION  
LAYER, BETWEEN 4 AND 8 KFT. CAN'T COMPLETELY RULE OUT A  
BRIEF/ISOLATED LOW-TOPPED AFTERNOON SPRINKLE, BUT NOT WORTH A  
MENTION IN ANY FORECAST PRODUCTS. ANTICYCLONIC CIRCULATION BUILDS  
OVER THE PLAINS AND DRIFTS EASTWARD FRIDAY NIGHT WITH A RIDGE-  
RUNNING SHORTWAVE/MCS EXPECTED TO SPILL INTO LOWER MICHIGAN. BY MOST  
METRICS, THIS SYSTEM SHOULD LIKELY DISSIPATE OVER THE WESTERN HALF  
OF THE STATE.  
 
DEW POINTS WILL SPIKE INTO THE 70S ON SATURDAY VIA A CONFLUENT LLJ  
SOURCED BY GULF MOISTURE AND SOME DEGREE OF PRE-FRONTAL POOLING FROM  
THE UPPER MIDWEST AS A BROAD UPPER LOW SPINS THROUGH CENTRAL CANADA.  
THIS LAYS THE GROUNDWORK FOR INCREASING INSTABILITY AS THE DAY  
PROGRESSES WITH HOT TEMPERATURES MARKED BY HIGHS IN THE LOWER 90S.  
BASED ON THE TRAILING NATURE OF THE COLD FRONT TO THE NORTH AND THE  
BLOCKING RIDGE TO THE SOUTH, IT WILL TAKE SOME TIME FOR THE FRONTAL  
BOUNDARY TO ACTUALLY ADVANCE INTO SOUTHEAST MICHIGAN. DO EXPECT AN  
EVENTUAL INCREASE IN STORM POTENTIAL SOUTHWARD SATURDAY, BUT TIMING  
UNCERTAINTY REMAINS HIGH UNTIL LATER SATURDAY EVENING/NIGHT.  
LOCATIONS NORTH OF M-46 WOULD BE MORE LIKELY TO SEE DIURNAL STORM  
ACTIVITY COMPARED TO AREAS FURTHER DOWNSTATE. SPC DID OPT FOR A DAY  
3 MARGINAL WHICH IS FAIR GIVEN POTENTIAL FOR MLCAPE IN EXCESS OF 750  
J/KG AND EBS OF 25 KNOTS, ALTHOUGH SOME CAP EROSION WILL BE  
REQUIRED. HEAT INDICES COULD ALSO BE OF CONCERN, BUT NOT ENOUGH FOR  
A HEAT-RELATED HEADLINES AS MAX VALUES SHOULD PEAK IN THE UPPER 90S.  
SHOWER AND STORM CHANCES LINGER INTO SUNDAY UNTIL THE COLD FRONT  
CLEARS SOUTH BRINGING MUCH COOLER CONDITIONS THROUGH THE EARLY WEEK  
PERIOD.  
 
 
   
MARINE  
 
HIGH PRESSURE CENTERED OVER JAMES BAY WITH A SURFACE RIDGING  
EXTENDING INTO THE CENTRAL GREAT LAKES PROMOTING LIGHT NORTHEAST-  
EAST WINDS THIS AFTERNOON UNDER 15 KNOTS.  
 
RETURN FLOW AROUND DEPARTING HIGH PRESSURE WILL ALLOW WINDS TO FLIP  
AROUND TO THE SOUTH TONIGHT-SATURDAY, BUT WINDS STILL LOOK TO BE  
GENERALLY LIGHT (UNDER 20 KNOTS). TRENDS FOR THE SECOND HALF OF THE  
WEEKEND INDICATE A FASTER AND STRONGER COLD FRONT DROPPING SOUTH  
THROUGH THE CENTRAL GREAT LAKES. THERE IS A CHANCE FOR STORMS BY  
SATURDAY EVENING ALREADY, WITH SCATTERED-NUMEROUS SHOWERS AND  
THUNDERSTORMS AROUND SATURDAY NIGHT INTO SUNDAY. SOLID COLD  
ADVECTION (850 MB TEMPS LOWERING INTO LOWER TEENS/AROUND 10 C) OVER  
LAKE HURON ON SUNDAY WILL ALLOW NORTHEAST WINDS TO REACH 20-25  
KNOTS, WITH THE POTENTIAL FOR WINDS TO BRIEFLY GUST TO AROUND 30  
KNOTS. EVEN IF WINDS COME UP A BIT SHORT, THE PROLONG NORTHEAST  
WINDS WILL LIKELY ALLOW WAVES TO BUILD AROUND 4 FEET ACROSS THE  
NEARSHORE WATERS, AS EASTERLY WINDS PERSIST INTO EARLY NEXT WEEK  
WITH ANOTHER STRONG HIGH PRESSURE SYSTEM DEVELOPING OVER EASTERN  
CANADA.  
 
 
   
PREV DISCUSSION  
 
ISSUED AT 120 PM EDT THU AUG 14 2025  
 
AVIATION...  
 
HIGH PRESSURE IN PLACE THROUGH THE FORECAST PERIOD MAINTAINING QUIET  
AVIATION WEATHER. VFR DIURNAL CU THIS AFTERNOON FADES AFTER SUNSET  
FAVORING CLEAR OVERNIGHT SKIES. LIGHT EAST-NORTHEAST WINDS FURTHER  
LESSEN OVERNIGHT BEFORE DIURNAL SOUTHERLY FRIDAY.  
 
FOR DTW/D21 CONVECTION...NO THUNDERSTORMS EXPECTED THROUGH THIS TAF  
PERIOD.  
 
THRESHOLD PROBABILITIES...  
 
* LOW FOR CEILINGS AT OR BELOW 5 KFT THIS AFTERNOON.  
 
 
   
DTX WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
LAKE HURON...NONE.  
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  
 
 
 
 
DISCUSSION...KGK  
MARINE.......SF  
AVIATION.....KDK  
 
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