332  
FXUS63 KDTX 150851  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
351 AM EST SUN DEC 15 2024  
   
KEY MESSAGES  
 
 
- POTENTIAL FOR SLICK CONDITIONS ACROSS THE SAGINAW VALLEY THIS  
MORNING AS FREEZING RAIN TRACKS THRU THE AREA. A WINTER WEATHER  
ADVISORY REMAINS IN EFFECT.  
 
- WARMER CONDITIONS TODAY AS AREAS OF LIGHT RAIN PERSIST.  
 
- SEASONABLY WARM TEMPERATURES BREAK THE 50 DEGREE MARK (SOUTH OF I-  
69) MONDAY WITH MORE RAIN, THEN READINGS DECLINE THROUGHOUT THE  
WORKWEEK.  
 
 
   
DISCUSSION  
 
EARLY MORNING SURFACE ANALYSIS SHOWS LOW PRESSURE TRACKING ACROSS  
WESTERN ILLINOIS, WITH A WARM FRONTAL ZONE STRETCHING EASTWARD INTO  
OHIO VALLEY. CORRIDOR OF MOIST ISENTROPIC ASCENT EMANATING NORTH OF  
THESE FEATURES MAINTAINED WITHIN THE BROADER REGION OF ELEVATED WARM  
AIR ADVECTION, RESULTING IN AN EXPANSIVE PRECIPITATION SHIELD NOW  
MAKING INROADS THROUGHOUT SOUTHEAST MICHIGAN. DRY EASTERLY FLOW  
EFFECTIVELY RELENTING FROM SOUTH TO NORTH AS SUFFICIENT MAGNITUDE TO  
THETA-E ADVECTION WORKS TO SATURATE THE PROFILE, WHILE A WARMING  
COLUMN ENSURES THIS ARRIVES IN LIQUID FORM. PERUSAL OF LOCAL  
OBSERVATIONS SUGGEST ADEQUATE NEAR SURFACE WARMING NOW ALLOWING  
TEMPERATURES FOR MOST LOCATIONS OUTSIDE OF THE SAGINAW VALLEY TO  
RESIDE SAFELY ABOVE FREEZING, MEANING SIMPLY JUST RAIN GOING  
FORWARD. WINDOW REMAINS ACROSS THE SAGINAW VALLEY FOR FREEZING RAIN  
TO GENERATE SOME LIGHT ICE ACCUMULATION OVER THE NEXT SEVERAL HOURS.  
WINTER WEATHER ADVISORY REMAINS IN EFFECT THROUGH 12Z FOR THIS  
CORRIDOR.  
 
MOIST AND MILDER CONDITIONS WILL EXIST THROUGHOUT SUNDAY AS THE  
TRAILING CLOSED LOW MEANDERS ACROSS THE REGION ATOP AN INCREASINGLY  
DIFFUSE WARM FRONT/TROUGH AXIS. THIS PATTERN MAINTAINS UNSETTLED  
CONDITIONS AS FOCUSED AREAS OF DCVA WITHIN THE UNDERLYING MID LEVEL  
CYCLONIC FLOW CONTRIBUTES ADDITIONAL POCKETS OF LIGHT RAIN/DRIZZLE  
DURING THE DAYLIGHT HOURS. THE MODERATING THERMAL PROFILE WILL  
SUPPORT HIGHS NEAR 40 DEGREES. A QUICK TRANSITION TOWARD BUILDING  
UPPER HEIGHTS TONIGHT WITH THE BACKGROUND OF SOUTH TO SOUTHEAST LOW  
LEVEL WILL MINIMIZE ANY NOCTURNAL COOLING POTENTIAL, LEAVING LOWS  
WITHIN SEVERAL DEGREES OF LATE DAY READINGS.  
 
WARMING TREND SOLIDIFIED HEADING INTO MONDAY AS FLOW VEERS TO  
SOUTHWESTERLY AND INCREASES DEPTH IMMEDIATELY DOWNSTREAM OF THE NEXT  
INBOUND UPPER WAVE. ANOTHER QUICK SHOT OF MEANINGFUL MOIST  
ISENTROPIC ASCENT WITHIN THE STRENGTHENING PATTERN OF WARM AIR  
ADVECTION RESULTS IN A HIGH PROBABILITY, LIGHT RAINFALL EVENT DURING  
THE DAYLIGHT PERIOD. COLLECTIVE ENSEMBLE SOLUTION SPACE ONBOARD WITH  
THIS OUTCOME. TEMPERATURES PEAK THIS PERIOD NEAR 50 DEGREES. MODEST  
COLD AIR ADVECTION EMERGES MONDAY EVENING INTO THE OVERNIGHT HOURS  
AS HEIGHT FALLS COMMENCE WITH THE UPPER TROUGH PASSAGE. THE  
ADVECTIVE PROCESS LACKS STRENGTH GIVEN PACIFIC ORIGIN, BUT MAY  
CONTRIBUTE TO SOME GUSTINESS OF WEST-SOUTHWEST WIND OVERNIGHT WITHIN  
THE POST-FRONTAL ENVIRONMENT AS PROJECTED WINDS OF 30-35 KNOTS EXIST  
AT THE TOP OF THE MIXED LAYER.  
 
A MILDER RESIDENT THERMAL PROFILE WILL HOLD INTO THE MIDWEEK PERIOD,  
AS THE LARGE SCALE PATTERN REMAINS GOVERNED BY LOWER AMPLITUDE FLOW  
OF POLAR ORIGIN. DRY AND GUSTY CONDITIONS PERSIST INTO TUESDAY  
WITHIN A FIRM WESTERLY GRADIENT. A BRIEF PERIOD OF MEANINGFUL FORCED  
ASCENT WILL ATTEMPT TO MATERIALIZE WEDNESDAY WITHIN THE NORTH FLANK  
OF LOW PRESSURE TRACKING ACROSS THE OHIO/TENNESSEE VALLEY AND ALONG  
A COLD FRONT ATTENDANT TO ADDITIONAL INBOUND HEIGHT FALLS FROM THE  
NORTH. AN ILL-DEFINED SETUP AT THIS STAGE OWING TO EXPECTED  
DEVIATION WITHIN THE MODEL SOLUTION SPACE ON PLACEMENT AND  
INTERACTION OF KEY FEATURES. FORECAST WILL CONTINUE TO OFFER A MORE  
GENERAL OUTLOOK FOR THE POSSIBILITY OF LIGHT RAIN AND SNOW GIVEN  
MARGINAL MELTING LAYER DEPTH FOCUSED DURING THE DAYLIGHT PERIOD  
WHERE TEMPS PEAK IN THE MID/UPPER 30S.  
 
 
   
MARINE  
 
SOUTHEAST WINDS OF 15 TO 25 KNOTS CONTINUE OVER LAKE HURON TODAY,  
ALLOWING 4+ WAVES TO IMPACT THE NEARSHORE ZONES. WINDS ATTEMPTING TO  
BECOME MORE DUE SOUTHERLY INTO SUNDAY NIGHT. WARMER AIR WILL  
GRADUALLY WORK INTO THE REGION ALLOWING FOR PRECIPITATION TO FALL  
FALL AS RAIN TODAY AS WEAKENING LOW PRESSURE TRACKS IN FROM THE  
MIDWEST. THIS LOW AND ANY COLD AIR FIZZLE OUT IN FAVOR OF THE  
STRONGER/MORE AMPLIFIED UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS  
SUNDAY NIGHT.  
 
RESUMED MODERATE SOUTHERLY FLOW CAN BE EXPECTED WITH ADDITIONAL RAIN  
BY MONDAY. COLD FRONT, ATTACHED TO LOW PRESSURE TRACKING THROUGH  
ONTARIO AND NEAR JAMES BAY, WILL SWING THROUGH THE CENTRAL GREAT  
LAKES EARLY MONDAY EVENING. TIGHT PRESSURE GRADIENT WITH 850 MB  
TEMPS LOWERING TO AROUND -8 C LOOKS SUPPORTIVE OF WIND GUSTS IN  
THE 30 TO 35 KNOT RANGE OVER CENTRAL AND NORTHERN LAKE HURON, LATE  
MONDAY NIGHT INTO EARLY TUESDAY MORNING. HOWEVER, GUSTS TO GALES  
APPEAR TO BE BRIEF, AS THE PRESSURE GRADIENT QUICKLY RELAXES DURING  
THE DAY ON TUESDAY. THUS, NOT PLANNING ON GALE WATCH AT THIS TIME.  
 
AN EVEN STRONGER COLD FRONT LOOKS TO BE MOVING THROUGH ON WEDNESDAY,  
AND NORTHERLY WINDS LATE WEDNESDAY THROUGH THURSDAY MORNING WILL  
LIKELY REACH INTO THE 20 TO 30 KNOT RANGE, BUT ULTIMATELY INFLUENCED  
BY THE STRENGTH AND POSITION OF LOW PRESSURE TRACKING THROUGH/NEAR  
THE SOUTHERN OHIO VALLEY. A RIDGE OF HIGH PRESSURE QUICKLY FOLLOWS,  
ALLOWING FOR A PERIOD OF LIGHT WINDS TO END THE WORK WEEK.  
 
 
   
PREV DISCUSSION  
 
ISSUED AT 1152 PM EST SAT DEC 14 2024  
 
AVIATION...  
 
PRECIPITATION WILL OVERSPREAD THE AREA OVERNIGHT REACHING TERMINALS  
BETWEEN 07Z-09Z. KYIP/KDTW/KDET WILL SEE ALL RAIN WITH TEMPERATURES  
IN THE MID 30S WITH KPTK/KFNT ON EDGE OF RAIN/FREEZING RAIN AND KMBS  
STARTING AS FREEZING RAIN AND SWITCHING TO RAIN SHOWERS BY EARLY  
SUNDAY MORNING. PERIODIC RAIN SHOWERS WILL THEN PERSIST THROUGH THE  
DAY SUNDAY. CIGS WILL LOWER QUICKLY TO IFR LATE TONIGHT AND REMAIN  
SO SUNDAY WITH LIFR POSSIBLE. VSBY RESTRICTIONS OF 2-5SM IN RAIN/BR  
WILL BE COMMON. SHOWERS WILL TAPER OFF SUNDAY EVENING WITH PERHAPS  
SOME MINOR CIG IMPROVEMENT INTO THE END OF THIS FORECAST PERIOD.  
 
FOR DTW...PRECIPITATION WILL START AS RAIN AND REMAIN SO AS PERIODIC  
SHOWERS PERSIST THROUGH SUNDAY.  
 
DTW THRESHOLD PROBABILITIES...  
 
* HIGH FOR CEILINGS AOB 5KFT LATE TONIGHT INTO SUNDAY NIGHT.  
 
* MEDIUM THAT PRECIPITATION BEGINS AS ALL RAIN AROUND 08Z, HIGH IN  
PRECIPITATION BEING ALL RAIN SUNDAY.  
 
 
   
DTX WATCHES/WARNINGS/ADVISORIES  
 
MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ047-048-  
053.  
 
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LHZ421.  
 
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LHZ441-442.  
 
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LHZ443.  
 
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  
 
 
 
 
DISCUSSION...MR  
MARINE.......SF  
AVIATION.....DG  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
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