316  
FXUS63 KDTX 170005  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
805 PM EDT SAT AUG 16 2025  
   
KEY MESSAGES
 
 
- ADDITIONAL SHOWER AND THUNDERSTORM CHANCES EXIST TONIGHT AND AGAIN  
MONDAY-TUESDAY. LOCALLY HEAVY RAINFALL IS POSSIBLE.  
 
- COOLER AND DRIER CONDITIONS EXPECTED WEDNESDAY THROUGH FRIDAY.  
 

 
   
AVIATION
 
 
UNCERTAINTY STILL EXISTS WITH EXACT TIMING OF SHOWERS AND  
THUNDERSTORMS OVER THE AREA LATER THIS EVENING AND TONIGHT. ACTIVITY  
AT THE START OF THE TAF PERIOD SHOULD MOSTLY AVOID TERMINALS, ASIDE  
FROM A STRAY LIGHT SHOWER. THERE IS CURRENTLY A WEAKENING AREA  
SHOWERS OVER LAKE MICHIGAN MOVING ONSHORE, WHICH SEVERAL MODELS ARE  
STRUGGLING WITH. EXPECTATION IS FOR IT TO CONTINUE TO WEAKEN WITH  
TIME, BUT IT IS POSSIBLE SCATTERED SHOWER ACTIVITY REACHES INTO  
SOUTHEAST MICHIGAN LATER. THERE REMAINS POTENTIAL FOR SCATTERED RAIN  
AND THUNDERSTORMS LATE TONIGHT (02Z-09Z) AS A COLD FRONT DROPS SOUTH  
WITH ENHANCED UPPER LEVEL LIFT ARRIVING AS WELL. WILL FOCUS TEMPO  
GROUPS WITHIN THIS TIME FRAME. WINDS TURN NORTHERLY BEHIND FRONT WITH  
LOWERING CEILINGS AND POTENTIAL FOR MVFR FOG ALONG AND IN THE WAKE  
OF THE FRONT THROUGH TOMORROW MORNING. NORTH TO NORTHEAST WIND GUSTS  
TO 20-25 KNOTS EXPECTED AS DAYTIME MIXING ENSUES NEAR THE EARLY  
AFTERNOON.  
 
FOR DTW/D21 CONVECTION...TIMING OF THUNDERSTORMS STILL LOOKS TO BE  
AFTER 03Z IF NOT WELL AFTER. CURRENT TRENDS HAVE MUCH OF THE CURRENT  
ACTIVITY WEAKENING. STILL ANTICIPATE AN INCREASE IN COVERAGE AT SOME  
POINT BETWEEN 03Z-09Z WITH THE FRONT, WITH DTW LEANING TOWARDS THE  
LATER PORTION OF THIS TIME FRAME.  
 
THRESHOLD PROBABILITIES...  
 
* MEDIUM FOR THUNDERSTORMS OVERNIGHT - MAINLY AFTER 03Z.  
 
* HIGH FOR CEILINGS AT OR BELOW 5 KFT AFTER 06Z INTO MUCH OF SUNDAY.  
 

 
   
PREV DISCUSSION
 
 
ISSUED AT 359 PM EDT SAT AUG 16 2025  
 
DISCUSSION...  
 
TAIL OF CONVECTION FLANKING TO THE SOUTHWEST OF AN OLD MCV FEATURE  
HAS RESULTED IN ELEVATED SHOWER AND THUNDERSTORM ACTIVITY OVER  
EASTERN PORTIONS OF THE THUMB THIS AFTERNOON. SURFACE OBSERVATIONS  
PICKED UP ON RELATIVELY STRONGER NORTHEAST FLOW, UP TO 25 KNOTS, IN  
ADVANCE OF THE MCV SIGNIFYING THE ORGANIZATION OF THE SYSTEM.  
THUNDERSTORM ACTIVITY WILL LIKELY CONTINUE TO FIRE AND ZIPPER OPEN  
FOR A TIME AS THE CONVERGENCE AXIS TRIES TO WORK OUT OF THE STATE.  
UPSTREAM OVER WISCONSIN, THE DEEPEST OF CONVECTION IS SETTING UP ON  
THE SOUTHERN PERIPHERY OF THE NEXT MCS/MCV. TOUCHED ON THE  
EXPECTATIONS FOR TIMING OF THUNDERSTORMS AND THE POTENTIAL OF SEVERE  
WEATHER IN THE UPDATE DISCUSSION ISSUED EARLIER. MUCH OF THIS  
PREVIOUS THINKING REMAINS VALID.  
 
STORM SCALE SUBSIDENCE IS FORECASTED TO COMBINE WITH STRENGTHENING  
NORTHERLY FLOW LATE TONIGHT IN SHAPING UP A NEAR SURFACE COLD FRONT  
OVER THE STATE. LATEST PLAN VIEW PROGS OF THETAE SUPPORT THIS COLD  
FRONT PUSHING SOUTHWARD INTO THE NORTHERN OHIO RIVER VALLEY BETWEEN  
12-15Z SUNDAY. FORECAST SOUNDINGS SIGNAL ACTIVE SUBSIDENCE  
DEVELOPING BETWEEN 6.0 AND 12.0 KFT EARLY IN THE DAY, THEN DEEPENING  
AND LOWERING TOWARD THE SURFACE DURING THE COURSE OF THE AFTERNOON.  
OUTSIDE OF A ROGUE SHOWER OR SPRINKLE DOWNWIND OF THE GREAT LAKES,  
RELATIVELY HIGH CONFIDENCE IN DRY CONDITIONS FOR MUCH OF THE AREA  
SUNDAY. GUSTY NORTH WINDS 10 TO 20 MPH WITH DECREASING HUMIDITY LATE  
IN THE DAY.  
 
SURFACE HIGH PRESSURE IS FORECASTED TO BUILD AGGRESSIVELY INTO THE  
STATE FOR MONDAY WITH DEEP COLUMN RIDGING. FORECAST SOUNDINGS  
SUPPORT EXTREMELY STRONG STABILITY DEVELOPING IN THE 4.0 TO 16.0 KFT  
AGL. MODESTLY LESS HUMID CONDITIONS ESPECIALLY AS DEEPER MIXING  
OCCURS DURING THE AFTERNOON. HIGHS ARE EXPECTED TO RANGE IN THE  
LOWER 80S.  
 
FORECAST MODELS SUPPORT THE BROAD LONGWAVE RIDGE AMPLIFYING OVER  
MUCH OF NORTH AMERICA QUICKLY LATE MONDAY AND TUESDAY. SIGNS POINT  
TO A WEAKNESS IN THE RIDGE CORRESPONDING TO A VERY WEAK JET AXIS  
DIRECTED AT THE WESTERN AND CENTRAL GREAT LAKES TUESDAY. RELATIVELY  
HIGHER PREDICTABILITY APPEARS TO EXIST WITH A MCS AND LARGER LOW  
PRESSURE CIRCULATION TRACKING IN VICINITY OF SOUTHEAST MICHIGAN. THE  
MOST EYE CATCHING ITEM OF THIS MIDWEEK SYSTEM IS THE SHARPNESS AND  
STRENGTH OF THETAE GRADIENT THAT WILL PUSH INTO THE AREA LATE MONDAY  
NIGHT. OVERALL, THE SPECIFICS OF THIS TUESDAY SYSTEM WILL COME DOWN  
TO TIMING OF THE COLD FRONT AND WHETHER OR NOT AN UPSTREAM  
CONVECTIVE SYSTEM TRACKS THROUGH THE AREA. COULD LOOK AT AN EARLY  
TUESDAY MORNING TIMING THAT SHORT CIRCUITS AIRMASS RECOVERY ON  
TUESDAY. WILL BE MONITORING TRENDS FOR A HEAVY RAINFALL THREAT.  
 
UPPER LEVEL RIDGING IS EXPECTED TO BRING AN EXTENDED RUN OF DRY  
WEATHER FOR THE END OF THE WEEK. CURRENT FORECAST DATA SUGGESTS MUCH  
LESS HUMID WEATHER LATE WEDNESDAY THROUGH FRIDAY.  
 
MARINE...  
 
CONTINUED LOW LEVEL WARMING TODAY AHEAD OF A COLD FRONT SHOULD CAP  
SOUTHERLY WIND SPEEDS IN THE 15 TO 20 KNOT RANGE. NUMEROUS SHOWERS  
AND THUNDERSTORMS DEVELOPING BY THIS EVENING AS THE COLD FRONT  
ENTERS THE REGION. ALTHOUGH THE FRONT QUICKLY DROPS SOUTH OF THE  
STATE SUNDAY MORNING, STILL A LINGERING CHANCE OF SHOWERS AND  
THUNDERSTORMS FOR GOOD PORTION OF THE DAY. STRONG HIGH PRESSURE  
BUILDING OVER NORTHWEST ONTARIO AND SOLID COLD ADVECTION (850 MB  
TEMPS LOWERING INTO LOWER TEENS) OVER LAKE HURON ON SUNDAY WILL  
ALLOW NORTHEAST WINDS TO REACH 20-25 KNOTS, WITH STILL THE POTENTIAL  
FOR WINDS TO BRIEFLY GUST TO AROUND 30 KNOTS. EVEN IF WINDS COME UP  
A BIT SHORT, THE PROLONG NORTHEAST WINDS WILL ALLOW WAVES TO BUILD  
IN EXCESS OF 4 FEET ACROSS THE NEARSHORE WATERS OF LAKE HURON, AS  
EASTERLY WINDS PERSIST INTO EARLY NEXT WEEK WITH ANOTHER STRONG HIGH  
PRESSURE SYSTEM DEVELOPING OVER EASTERN CANADA.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...BEACH HAZARDS STATEMENT FROM SUNDAY MORNING THROUGH SUNDAY EVENING  
FOR MIZ048-049-055-063.  
 
LAKE HURON...SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO NOON EDT MONDAY FOR LHZ421-  
441.  
 
SMALL CRAFT ADVISORY FROM NOON SUNDAY TO MIDNIGHT EDT SUNDAY NIGHT  
FOR LHZ422.  
 
SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 8 AM EDT MONDAY FOR  
LHZ442-443.  
 
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  

 
 

 
 
AVIATION.....AA  
DISCUSSION...CB  
MARINE.......SF  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
 
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