797  
FXUS63 KDTX 201155  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
655 AM EST THU FEB 20 2025  
   
KEY MESSAGES  
 
 
- WIDESPREAD LIGHT SNOW WILL TAPER OFF THROUGH THE MORNING, BECOMING  
DRY FOR MOST THIS AFTERNOON.  
 
- NORTHERLY WINDS MAY PUSH A LAKE EFFECT SNOW BAND OFF LAKE HURON  
INTO THE NORTHERN AND EASTERN THUMB WHICH COULD RESULT IN SOME  
ADDITIONAL SNOW ACCUMULATIONS.  
 
- WARMING TREND WILL COMMENCE HEADING INTO THE WEEKEND WITH HIGH  
TEMPERATURES BACK UP TO FREEZING BY SUNDAY, AND UP TO AROUND 40  
MONDAY THROUGH WEDNESDAY.  
 
 
   
AVIATION  
 
LIGHT SNOW WILL GRADUALLY TAPER OFF ACROSS ALL TERMINALS THIS  
MORNING. MVFR TO IFR CONDITIONS ASSOCIATED WITH SNOW WILL GRADUALLY  
IMPROVE TO PREDOMINATELY MVFR CEILINGS AS SNOWFALL COMES TO AN END  
BY AROUND 15-16Z. MVFR CEILINGS THEN LINGER THROUGH THE AFTERNOON  
WITH WINDS OUT OF THE NORTHWEST AT OR NEAR 10 KNOTS. CLOUDS MY TRY  
TO SCATTER OUT THIS EVENING INTO TONIGHT, BUT WILL MAINTAIN A MORE  
PESSIMISTIC FORECAST WITH CLOUD BASES STICKING AROUND 3KFT.  
 
FOR DTW... LIGHT SNOW AVERAGES IFR VISIBILITY TO START THE TAF  
PERIOD SHOULD GRADUALLY IMPROVE TO MVFR INTO THE LATE MORNING AS  
SNOWFALL COMES TO AN END BY AROUND 15-16Z.  
   
DTW THRESHOLD PROBABILITIES  
 
* HIGH FOR CEILING AT OR BELOW 5000 FEET TODAY AND MODERATE TONIGHT.  
 
* HIGH FOR SNOW AS PRECIPITATION TYPE THIS MORNING.  
 
 
   
PREV DISCUSSION  
 
ISSUED AT 342 AM EST THU FEB 20 2025  
 
DISCUSSION...  
 
WIDESPREAD LIGHT SNOW IS ONGOING AND WILL CONTINUE THROUGH THE  
MORNING HOURS. THERE WILL BE A DECREASING TREND THROUGH THIS TIME  
FROM NW TO SE AS THE UPPER LOW NOW CENTERED OVER CLE WILL CONTINUE  
DRIFTING EASTWARD, PULLING THE WEAKENING DEFORMATION AXIS AWAY WHILE  
ALSO DRAWING THE LAKE TROUGH SOUTHWARD AS WELL. THE RESULTING  
NORTHWESTERLY FLOW WILL OFFER AN INCREASINGLY DRIER AIRMASS THROUGH  
THE AFTERNOON. ANY ADDITIONAL ACCUMULATIONS THROUGH THE MORNING WILL  
BE MAYBE A TENTH OR TWO, KEEPING TOTALS GENERALLY AROUND A HALF INCH.  
WE DO CONTINUE TO WATCH THE EASTERN AND NORTHERN THUMB FOR THE  
POTENTIAL FOR THE NORTHEASTERLY WINDS OVER THE LAKE PUSH THE LAKE  
BAND TOWARDS SHORE BEFORE BACKING MORE TOWARD THE NORTHWEST, PUSHING  
THE BAND BACK OVER THE LAKE. HIRES MODELS GIVE THE TYPICAL SPREAD,  
VARYING FROM IT PUSHING ALL THE WAY THROUGH BAD AXE OR STAYING  
OFFSHORE ALTOGETHER. LUCKILY, AS MENTIONED IN THE EVENING UPDATE,  
THE CONVECTIVE DEPTH THROUGHOUT THE SOUNDINGS IS FIRMLY AROUND 5-  
6KFT THANKS TO THE STOUT RIDGE ALOFT, LIMITING THE SNOWFALL  
POTENTIAL WITH THIS SETUP. WILL KEEP THE ACCUMULATIONS AROUND AN  
INCH FOR NOW.  
 
HIGH PRESSURE OVER THE PLAINS WILL BUILD EASTWARD THROUGH THE REST  
OF THE WEEK, EVENTUALLY ENCOMPASSING THE ENTIRE CONUS EAST OF THE  
ROCKIES. 500MB HEIGHTS WILL ALSO BE INCREASING AS THE WESTERN RIDGE  
GETS DRAWN INTO THE REGION IN THE WAKE OF TODAYS TROUGH. NOT THE  
CLEANEST RIDGE AS A SHORTWAVE TROUGH GETS CUTOFF OVER THE FOUR  
CORNERS AND SEVERAL WEAK SHORTWAVES WORK THROUGH THE NORTHWESTERLY  
FLOW BUT WITH THE LACK OF A DOMINATE NORTHERN STREAM JET CHANNEL,  
THE TRACKS OF ONE WAVE TO THE NEXT MAY WAVER THROUGHOUT THE BROADER,  
WEAKER FLOW. LOOKS LIKE WE SHOULD REMAIN DRY WITH THE RIDGING  
THROUGHOUT THE COLUMN, BUT PRECIP CHANCES RETURN SUNDAY AND THEN WE  
COULD GET INTO A PROGRESSIVE PATTERN WITH A WAVE RIPPLING THROUGH  
THE REGION ONCE A DAY.  
 
PTYPE MAY BECOME A CONCERN HEADING INTO NEXT WEEK AS THE MODERATING  
AIRMASS WITHIN THE AIRMASS, AND SURFACE RIDGE SHIFTING EAST ALLOWING  
FOR WEST/SW FLOW TO WARM US BACK TO AROUND 40 FOR HIGHS MONDAY AND  
BEYOND.  
 
MARINE...  
 
WEAK LOW PRESSURE BRINGS RELATIVELY LIGHT WINDS AND WIDESPREAD LIGHT  
SNOW THROUGH THE MORNING HOURS. AS THE SYSTEM DEPARTS THIS  
AFTERNOON, NORTH TO NORTHWEST WIND WILL INCREASE TO AROUND 20 KNOTS  
THROUGH TONIGHT WITH MORE LOCALIZED LAKE EFFECT SNOW SHOWERS  
CONTINUING OVER LAKE HURON. HIGH PRESSURE BUILDS INTO THE MID-  
MISSISSIPPI VALLEY ON FRIDAY WITH A RIDGE EXTENDING NORTHEAST INTO  
THE GREAT LAKES TO MAINTAIN A PERIOD OF LIGHTER WINDS THROUGH THE  
DAY. SOUTHWEST WIND THEN BEGINS TO INCREASE AGAIN FRIDAY NIGHT INTO  
SATURDAY AS THE RIDGE PASSES EAST AND MILDER AIR BEGINS TO WORK IN.  
WIND MAGNITUDE AGAIN LOOKS TO TOP OUT AROUND 20 TO 25 KNOTS, BUT  
THERE WILL BE A CHANCE FOR SOME 30 KNOT GUSTS OVER PARTS OF LAKE  
HURON SATURDAY AFTERNOON AND EVENING AS A COLD FRONT APPROACHES FROM  
THE NORTH. A CLIPPER SYSTEM WILL THEN DROP INTO THE REGION SUNDAY  
NIGHT INTO MONDAY BRINGING THE NEXT INCREASE IN SOUTH WINDS AHEAD OF  
IT.  
 
 
   
DTX WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
LAKE HURON...NONE.  
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  
 
 
 
 
AVIATION.....AA  
DISCUSSION...DRK  
MARINE.......TF  
 
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