120
FXUS63 KDTX 171755
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1255 PM EST TUE DEC 17 2024
KEY MESSAGES
- DRY CONDITIONS WITH ABOVE AVERAGE TEMPERATURES TODAY.
- AREA OF LIGHT SNOW WILL LIFT ACROSS THE AREA WEDNESDAY MORNING.
ACCUMULATION AT A HALF INCH OR LESS FOR MOST LOCATIONS WITH SOME
MELTING OF SNOW EXPECTED. A MORE LOCALIZED REGION OF UP TO AN INCH
WILL BE POSSIBLE NORTH OF I-69.
- POTENTIAL FOR ACCUMULATING SNOW STARTING LATE THURSDAY AND
CONTINUING THROUGH FRIDAY AS A LOW PRESSURE SYSTEM TRACKS THROUGH
THE AREA.
- MUCH COLDER CONDITIONS EXPECTED FOR THE WEEKEND.
AVIATION
SOLID MVFR STRATUS DECK AROUND 2-3KFT ACROSS LOWER MI THIS AFTERNOON
WILL HOLD FOR MOST OF THE REGION THROUGH TONIGHT. THERE IS A CHANCE
THAT HIGH PRESSURE SLIDING TO OUR SOUTH WILL OFFER A BRIEF PERIOD OF
VFR CIGS, AT LEAST FOR DTW/DET/YIP, BEFORE MVFR/IFR CIGS RETURN WITH
A PASSING COLD FRONT AND ASSOCIATE RAIN/SNOW AROUND 12Z.
PRECIPITATION MAY BEGIN AS SNOW BUT WILL TRANSITION TO RAIN/SNOW MIX
AS TEMPERATURES RISE ABOVE FREEZING SO NOT MUCH ACCUMULATION IS
EXPECTED. POSSIBLY UP TO A HALF INCH NORTH OF PTK. WINDS HAVE BEEN
DECREASING THIS MORNING AND ARE NOW MOSTLY BELOW 12 KNOTS WITH ONLY
AN OCCASIONAL GUST IN THE TEENS. AFTER GOING LIGHT AND VARIABLE
TONIGHT THEY WILL REEMERGE WEDNESDAY MORNING OUT OF WEST-NORTHWEST.
FOR DTW... BRIEF PERIOD OF LIGHT SNOW EXPECTED TO BEGIN AFTER 12Z
WEDNESDAY MORNING. TEMPERATURES WILL BE WARMING THROUGH THE MORNING
WHICH SHOULD TRANSITION PRECIPITATION FROM WET SNOW CHARACTER TO
MELTING SNOW. ANY ACCUMULATIONS WILL BE VERY LIGHT (TRACE TO TENTH
OF AN INCH), MAINLY ON GRASSY/ELEVATED SURFACES. SNOW WILL THEN
TAPER OFF EARLY WEDNESDAY AFTERNOON.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CEILING AT OR BELOW 5000 FEET THIS MORNING AND THIS
AFTERNOON. MEDIUM THIS EVENING.
* HIGH FOR PRECIPITATION TYPE AS WET SNOW TRANSITIONING TO MELTING
SNOW WEDNESDAY MORNING.
PREV DISCUSSION
ISSUED AT 351 AM EST TUE DEC 17 2024
DISCUSSION...
BENIGN STRETCH OF WX OVER THE NEXT 24 HOURS, WITH CONDITIONS
GOVERNED BY WEAK LOW AND MID LEVEL RIDGING. FIRM RESPONSE NOTED
EARLY THIS MORNING WITHIN THE WIND FIELD AS MODEST COLD AIR ADVECTION
IN WESTERLY FLOW CAPITALIZES ON THE OVERALL INCREASE IN WIND
MAGNITUDE. GUST POTENTIAL WITHIN THE 30 TO 35 MPH RANGE WILL PERSIST
THROUGH THE MORNING, BEFORE EASING WITH TIME THIS AFTERNOON AS THE
GRADIENT RELAXES UNDER BUILDING HEIGHTS. MILDER THERMAL PROFILE STILL
IN RESIDENCE DESPITE THE RECENT COLD FRONTAL PASSAGE. TARGETED HIGH
TEMPERATURE RANGE FROM MID 30S NORTH TO LOWER 40S SOUTH.
A LIGHT QPF EVENT STILL ON TARGET FOR MAINLY THE MID-LATE MORNING
HOURS WEDNESDAY. POSITIVELY TILTED LONGWAVE TROUGH ANCHORED TO THE
ENTRANCE REGION OF 100 KNOT UPPER JET WILL INITIATE A BROAD REGION
OF LARGE SCALE FORCING CENTERED ON THIS WINDOW, WITH THE ASSOCIATED
INBOUND COLD FRONT OFFERING A LOWER LEVEL FOCUS FOR ASCENT.
ASSESSMENT OF SOUNDING DATA, THICKNESS LEVELS AND PERUSAL OF
PROBABILISTIC GUIDANCE ACROSS THE ENSEMBLE SPECTRUM LEND CONFIDENCE
FOR PRECIPITATION TYPE OF MAINLY LIGHT/MELTING SNOW. ACCUMULATION
POTENTIAL GENERALLY LIMITED BY LACK OF GREATER SNOWFALL RATES AND
SURFACE TEMPERATURES FIXATED NEAR FREEZING WHILE COMING OFF THIS
WARMER STRETCH. THERE REMAINS SOME POTENTIAL FOR A BRIEF, SMALLER
SCALE UPTICK IN SNOWFALL RATES OWING TO INCREASING FGEN AS THE
FRONTAL BOUNDARY INTERSECTS FAVORABLE UPPER JET FORCING. GREATER
POTENTIAL FOR THIS TO MATERIALIZE I-69 CORRIDOR NORTHWARD, PLACING A
CEILING ON ACCUMULATION POTENTIAL AT ROUGHLY AN INCH. OTHERWISE,
HALF INCH OR LESS MAINLY ON GRASSY SURFACES. ANY LINGERING POCKETS OF
PRECIPITATION WITHIN THE IMMEDIATE POST-FRONTAL ENVIRONMENT MAY
ARRIVE IN LIQUID FORM, AS TEMPERATURES EDGE INTO THE MIDDLE 30S
DURING THE AFTERNOON. ARRIVAL OF A TRAILING POLAR LOBE OF VORTICITY
OFFERS HIGHER MAGNITUDE COLD AIR ADVECTION WEDNESDAY EVENING INTO THE
OVERNIGHT PERIOD. THIS PROCESS MAY RESULT IN AN ISOLATED TO
SCATTERED COVERAGE OF SNOW SHOWERS, BUT A PROGRESSIVE SHIFT TOWARD
NORTHWEST FLOW SIGNALS A LIMITED LES CONTRIBUTION.
CLIPPER SYSTEM PROJECTED TO LIFT ACROSS THE GREAT LAKES THU/FRI.
STANDARD VARIABILITY STILL SHOWN WITHIN THE MODEL SOLUTION SPACE IN
TERMS OF THE EXACT PROJECTED TRACK, MAGNITUDE AND PLACEMENT OF
FORCED ASCENT, MOISTURE QUALITY PARTICULARLY WITHIN THE LEAD AXIS OF
WARM AIR ADVECTION AND RESIDENCE TIME OF ANY TRAILING DEFORMATION.
THESE DETAILS WILL COME INTO BETTER LIGHT AS GREATER UPPER AIR
SAMPLING COMMENCES IN THE NEXT 24-36 HOURS. IN GENERAL TERMS,
COLLECTIVE OF THE ENS AND GEPS ENSEMBLE SUITES OFFER NEARLY A 100
PERCENT CHANCE FOR SOME ACCUMULATION AREAWIDE THIS PERIOD, WITH ALL
BUT SEVERAL OUTLIERS SHOWING THE SAME ON THE GEFS. WARM AIR
ADVECTION ON THE LEAD FLANK OF THE INBOUND WAVE WOULD INITIATE THE
FIRST WINDOW FOR POTENTIAL SNOW PRODUCTION LATE THURSDAY, WITH A
TRANSITION TOWARD ELEVATED FRONTAL FORCING AND DEFORMATION WITHIN
ONGOING HEIGHT FALLS THURSDAY NIGHT INTO FRIDAY. THE PROBABILITY
SPACE WOULD SUGGEST A BROAD HALF TO TWO INCHES OF ACCUMULATION CARRIES
THE MOST LIKELY OUTCOME, BUT WITH A YET DEFINED STRIP OF GREATER
THAN TWO INCHES CERTAINLY IN PLAY WHILE MINIMAL ACCUMULATION ALSO
PLAUSIBLE /PARTICULARLY SOUTH/ SHOULD THE TRACK SHIFT OR THE SCALE
OF THE EVENT CONTRACT. MUCH COLDER AIR WILL ARRIVES IN THE WAKE OF
THIS SYSTEM WITH SINGLE DIGIT WIND CHILL LIKELY THIS WEEKEND.
MARINE...
GUSTY WSW FLOW IN THE WAKE OF LAST EVENING'S COLD FRONT WILL REMAIN
BETWEEN 20 AND 30 KNOTS THROUGH THE MORNING AS COOLER AIR WORKS INTO
THE CENTRAL GREAT LAKES. SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR
THE LAKE HURON NEARSHORE WATERS. THE PRESSURE GRADIENT WILL SLOWLY
WEAKEN THROUGH THE DAY AS HIGH PRESSURE SETTLES ACROSS THE OHIO
VALLEY, ALLOWING WINDS TO DECREASE THROUGH THE AFTERNOON. THE HIGH
PRESSURE SLIDES EAST EARLY WEDNESDAY, GIVING WAY TO THE NEXT COLD
FRONT WHICH BRINGS AN AREA OF LIGHT SNOW DURING THE DAY. WINDS
BEHIND THIS FRONT SHIFT TO NORTHWESTERLY BUT LOOK TO REMAIN
MODERATE, ON THE ORDER OF 15 TO 20 KNOTS, AS THE COLD ADVECTION WILL
BE RELATIVELY WEAK AND SHORT-LIVED. A RIDGE OF HIGH PRESSURE ON
THURSDAY BRINGS LIGHTER WINDS BEFORE THE NEXT STRONGER CLIPPER LOW
TRACKS IN FROM THE MIDWEST THURSDAY NIGHT INTO FRIDAY. THIS SYSTEM
WILL LIKELY BRING WIDESPREAD SNOW WITH A CHANCE FOR STRONGER NORTH
TO NORTHWEST WINDS IN ITS WAKE AS WELL AS COLD CONDITIONS THROUGH
THE WEEKEND.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LHZ421-422-
441>443.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....DRK
DISCUSSION...MR
MARINE.......TF
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