163  
FXUS63 KDTX 172244  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
544 PM EST MON FEB 17 2025  
   
KEY MESSAGES
 
 
 
- COLD WEATHER ADVISORY IN EFFECT FROM 9PM TONIGHT UNTIL 9AM TUESDAY  
FOR THE TRI CITIES AND THUMB. WIND CHILLS ARE EXPECTED TO RANGE  
BETWEEN 10 DEGREES BELOW ZERO AND 20 DEGREES BELOW ZERO ACROSS  
SOUTHEAST MICHIGAN.  
 
- LAKE EFFECT SNOW SHOWERS AND BLOWING SNOW PRODUCE RAPID DROPS IN  
VISIBILITY THROUGH THE EARLY EVENING HOURS.  
 
- ADDITIONAL LIGHT SNOWFALL CHANCES WEDNESDAY NIGHT INTO THURSDAY  
MORNING WITH WELL BELOW NORMAL TEMPERATURES HOLDING THROUGH THE MID  
TO LATE WEEK.  
 

 
   
AVIATION
 
 
THE COVERAGE OF LIGHT SNOW SHOWERS/FLURRIES ASSOCIATED WITH THE LAKE  
MICHIGAN MOISTURE PLUME WILL DIMINISH IN COVERAGE WITH THE LOSS IN  
DIURNAL MIXING THIS EVENING. THE LOW LEVEL WIND FIELDS WILL ALSO  
VEER TOWARD THE NORTH-NORTHWEST OVER LAKE MICHIGAN DURING THE NIGHT,  
FORCING LINGERING LAKE CLOUDS AND SNOW SHOWERS SOUTH OF THE  
TERMINALS. THIS WILL OPEN THE DOOR TO CLEARING ACROSS SE MI. WHILE  
THERE WILL BE SOME NIGHTTIME DECOUPLING IN THE BOUNDARY LAYER, THE  
GRADIENT WINDS WILL MAINTAIN AT LEAST AN 8 TO 12 KNOT WIND AT THE  
SURFACE TONIGHT.  
 
FOR DTW...THE VEERING OF THE LOW LEVEL WIND FIELDS THIS EVENING WILL  
DRIVE SOME RESIDUAL LIGHT SNOW SHOWERS/FLURRIES AND AREAS OF MVFR  
BASED CLOUDS ACROSS METRO OVER THE NEXT FEW HOURS. THIS LAKE EFFECT  
ACTIVITY WILL PUSH SOUTH AFTER 03Z.  
   
DTW THRESHOLD PROBABILITIES
 
 
* MODERATE IN CEILINGS AOB 5000 FEET THIS EVENING. LOW OVERNIGHT  
AND TUESDAY.  
 

 
   
PREV DISCUSSION
 
 
ISSUED AT 310 PM EST MON FEB 17 2025  
 
DISCUSSION...  
 
A MUCH BELOW AVERAGE PATTERN IS IN PLACE WITH DEEP HEMISPHERIC  
TROUGHING AND CONTINENTAL POLAR AIRMASS DISLODGED SOUTHWARD  
THROUGHOUT MUCH OF THE EASTERN UNITED STATES. LOOKING AT FAIRLY  
STATIC CONDITIONS OVER SOUTHEAST MICHIGAN THROUGHOUT THE NEXT 60  
HOURS AS AN ANOMALOUSLY BROAD UPPER LEVEL JET ENTRANCE REGION  
REMAINS PARKED OVER THE MIDWEST AND GREAT LAKES. ONLY DISCERNIBLE  
CHANGE WILL BE FOR THE JET AXIS TO DRIFT SOUTHWARD WHILE RETRACTING  
IN ITS MERIDIONAL EXTENT.  
 
DIURNAL HEATING AND INCREASED PLANETARY BOUNDARY LAYER DEPTHS UP TO  
THE 5.5 KFT AGL RESULTED IN MULTIPLE BANDED LAKE EFFECT OVER  
SOUTHEAST MICHIGAN TODAY. INTERMITTENT VISIBILITY DROPS TO LESS THAN  
1/2 SM HAVE BROUGHT SOME CONCERN, BUT RADAR RETURNS HAVE SHOWN  
TRANSIENT STRUCTURES WITH SHORT DURATION OF HEAVIER SNOW ACTIVITY,  
+25 DBZ ACTIVITY FOR ANY ONE LOCATION. A LOOK OUT THE WINDOW HERE AT  
THE OFFICE SUGGESTS MUCH OF THE VISIBILITY DROPS HAS BEEN DUE TO  
BLOWING SNOW BROUGHT ON BY OVERACHIEVING WINDS OF 30 TO 40 MPH.  
THUS, ADDED BLOWING SNOW TO THE GRIDS. LATER THIS AFTERNOON,  
FORECAST SOUNDINGS SHOW RISING LCL HEIGHTS WHICH SHRINKS THE DEPTH  
OF THE SUPERSATURATION WITH RESPECT TO ICE TO COLDER THAN -16 TO -  
17C. STILL EXPECTING LES TO CONTINUE INTO THE EARLY EVENING, BUT  
COVERAGE OF BANDS SHOULD THIN OUT FAIRLY QUICKLY. TWO CORRIDORS  
APPEAR TO BE MOST FAVORABLE FOR SOME CONTINUED LAKE EFFECT UNTIL THE  
EARLY EVENING, THE FIRST ALONG AND BETWEEN I 96 AND I 94, THE SECOND  
BEING IN HURON COUNTY DOWNWIND OF SAGINAW BAY. LOW LEVEL CONVERGENCE  
FIELDS THEN WEAKEN CONSIDERABLY WITH LOSS OF DAYTIME HEATING AND  
1000-850MB MEAN FLOW TURNS NORTHWESTERLY. WILL CONTINUE TO MONITOR  
OBSERVATIONAL AND TRAFFIC DATA TO GAIN SITUATIONAL AWARENESS OF  
IMPACTS.  
 
MAIN STORY WILL BE THE VERY COLD TEMPERATURES AND WINDCHILLS OVER  
SOUTHEAST MICHIGAN. A MIXED ENVIRONMENT PERSISTING OVERNIGHT WITH  
850MB TEMPERATURES OF -22 TO -23C WILL LEAD TO DANGEROUSLY COLD  
WINDCHILLS BEGINNING AFTER SUNDOWN. AFTER COORDINATION WITH  
SURROUNDING OFFICES, OPTED FOR A COLD WEATHER ADVISORY FOR THE TRI  
CITIES REGION AND THE THUMB FROM 9PM THIS EVENING TO 9AM TUESDAY.  
DAYTIME TEMPERATURES TUESDAY WILL AGAIN BE IN THE MIDDLE TEENS.  
 
BACKGROUND SYNOPTIC FORCING WILL LARGELY BE CONDUCIVE FOR SURFACE  
HIGH PRESSURE FOR THE REMAINDER OF THE WEEK. LOOKING AT A DRY AIR  
MASS WITH STABLE CONDITIONS BELOW 20.0 KFT AGL. THE EXCEPTION WILL  
BE WEDNESDAY NIGHT AS REMNANT ATLANTIC MOISTURE WRAPS AROUND AND  
FINALLY GETS ADVECTION INTO LOWER MICHIGAN FROM THE NORTH. COMBINE  
THIS WITH AN AMPLIFYING SHORTWAVE THROUGH THE TENNESSEE VALLEY,  
SATURATION IS EXPECTED TO BE GREAT ENOUGH FOR LIGHT SNOW ACTIVITY.  
THE UVV RESPONSE IS NOT ANTICIPATED TO BE THAT GREAT, AND WILL RELY  
ON A LAKE AGGREGATE TROUGH. CHANCE POPS ARE IN THE FORECAST FOR LATE  
WEDNESDAY NIGHT. TEMPERATURES ARE EXPECTED TO BE AROUND 5 TO 10  
DEGREES BELOW NORMAL TO CLOSE THE WORK WEEK.  
 
MARINE...  
 
FRIGID AIRMASS IN PLACE OVER THE GREAT LAKES REGION THROUGH  
TOMORROW, WITH A TIGHT PRESSURE GRADIENT IN PLACE SUPPORTING  
NORTHWEST WINDS TO 30 KNOTS THIS EVENING THROUGH TUESDAY, WITH EVEN  
A FEW STRAY GUSTS TO LOW END GALES IN SNOW SQUALLS OVER NORTHERN  
LAKE HURON. AS SUCH, THE FREEZING SPRAY WARNING HAS BEEN EXTENDED TO  
4 PM TUESDAY. WINDS FINALLY LOOK TO DECREASE IN SPEED TUESDAY  
EVENING/NIGHT WITH MODEST WARM MODIFICATION OF THE AIRMASS INTO  
WEDNESDAY. DESPITE MODERATE NORTHERLY WINDS ON THURSDAY, FURTHER  
WARMING WILL OCCUR INTO FRIDAY. MODERATE SOUTHWEST WINDS FOR THE  
FIRST HALF OF THE WEEKEND, AHEAD OF A MOSTLY DRY COLD FRONT DROPPING  
SOUTH FROM THE NORTHERN GREAT LAKES REGION.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...COLD WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST TUESDAY  
FOR MIZ047>049-053>055-062-063.  
 
LAKE HURON...HEAVY FREEZING SPRAY WARNING UNTIL 4 PM EST TUESDAY FOR LHZ361>363-  
462-463.  
 
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  

 
 

 
 
AVIATION.....SC  
DISCUSSION...CB  
MARINE.......SF  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab MI Page Main Text Page