611
FXUS63 KDTX 171031
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
531 AM 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
A POCKET OF CLEARING IS OBSERVED JUST SOUTH OF THE DTW CORRIDOR, AND
WILL HAVE A LOW CHANCE OF REACHING THE TERMINALS BETWEEN NOW AND 13Z
BEFORE A SECOND COLD FRONT TRACKS ACROSS THE AREA. CURRENT SOUTHWEST
FLOW WILL VEER TO THE WEST AS THE FRONT SLIDES THROUGH LATER THIS
MORNING, FOLLOWED BY RENEWED LOW LEVEL MOISTURE. THE FRONTAL PASSAGE
WILL ALSO DISLODGE THE WIND FIELD, WITH GUSTY WINDS SUBSIDING BELOW
15 KNOTS THROUGH THE MORNING. DEPENDING ON BOUNDARY LAYER MIXING, A
COMBINATION OF LOW VFR AND MVFR CEILINGS ARE POSSIBLE THIS AFTERNOON
AS STRATOCUMULUS STREAMS OFF OF LAKE MICHIGAN. HIGH PRESSURE OVER
THE OHIO VALLEY WILL BRIEFLY GAIN TRACTION OVER SE MICHIGAN THIS
EVENING, SHIFTING WINDS TO THE SOUTHWEST AND AFFORDING A MORE
ORGANIZED PERIOD OF CLEARING AHEAD OF THE NEXT WEATHER SYSTEM WHICH
WILL HAVE MINIMAL IMPACT ON SE MICHIGAN BEFORE 12Z WEDNESDAY.
FOR DTW... LIGHT SNOW WILL MOVE INTO THE AREA AROUND 12-13Z
WEDNESDAY MORNING. AIR TEMPERATURES MAY INITIALLY BE AT OR BELOW
FREEZING, BUT WILL RISE THROUGHOUT THE MORNING TO SUPPORT A
TRANSITION 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.....MV
DISCUSSION...MR
MARINE.......TF
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