154
FXUS63 KDTX 141630
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1130 AM EST TUE JAN 14 2025
KEY MESSAGES
- NUMEROUS TO WIDESPREAD SNOW SHOWERS ARE EXPECTED ACROSS METRO
DETROIT AND ANN ARBOR TODAY. THERE IS THE POTENTIAL FOR SNOW SQUALLS
WITHIN THIS ACTIVITY. A WINTER WEATHER ADVISORY IS IN EFFECT IN THIS
REGION TODAY.
- THERE IS ANOTHER CHANCE OF SNOW SQUALLS ON THURSDAY.
- THERE IS A 40 PERCENT CHANCE OF PRECIPITATION ON SATURDAY.
PRECIPITATION TYPE AND AMOUNTS CARRY A GOOD DEAL OF UNCERTAINTY AT
THIS STAGE IN THE FORECAST.
- SUB ZERO WIND CHILLS ARE FORECAST EARLY NEXT WEEK. THIS WILL BE
THE COLDEST AIRMASS TO AFFECT THE AREA SO FAR THIS SEASON.
AVIATION
SURFACE TROUGH WITH SOME ENHANCED SNOW SHOWERS TRACKING THROUGH THE
SOUTHERN TAFS AT THE START OF THE TAF PERIOD/EARLY THIS AFTERNOON.
ENOUGH DRYING AND SUBSIDENCE BEHIND THE TROUGH FOR POCKETS OF MOSTLY
CLEAR/PARTLY CLOUDY SKIES FOR THE REST OF THE AFTERNOON. STILL
LOOKING AT WINDS BRIEFLY GUSTING AROUND 20 KNOTS LATE THIS AFTERNOON
WITH WEST-NORTHWEST WINDS THEN SETTLING AOB 10 KNOTS FOR THIS
EVENING INTO WEDNESDAY MORNING. PROLONG WESTERLY FLOW OFF OF LAKE
MICHIGAN SHOULD THEN BE ABLE TO SUPPORT A BORDERLINE VFR/MVFR CIGS
TO RETURN THIS EVENING, AND THEN HOLD TONIGHT INTO WEDNESDAY. A FEW
STRAY FLURRIES ARE POSSIBLE AS WELL, BUT NOT ENOUGH CONFIDENCE TO
INCLUDE IN TAFS AT THIS TIME.
FOR DTW...ENHANCED SNOW SHOWERS TO IMPACT AIRPORT THROUGH 19Z AND
THEN TAPERING OFF AROUND 20Z. SNOW ACCUMULATIONS LIKELY ONLY AROUND
HALF AN INCH. WEST-NORTHWEST WINDS PICKING UP LATE THIS AFTERNOON,
WITH GUSTS POTENTIALLY REACHING 20 KNOTS. DRYING KICKS IN, WITH
SKIES/LOW VFR CLOUDS BECOMING VARIABLE.
DTW THRESHOLD PROBABILITIES...
* LOW FOR CIGS AOB 5000 FEET LATE THIS AFTERNOON AND THIS EVENING,
THEN MODERATE.
PREV DISCUSSION
ISSUED AT 310 AM EST TUE JAN 14 2025
DISCUSSION...
AN ELONGATED MID LEVEL TROUGH NOW EXTENDING ACROSS THE NORTHERN
GREAT LAKES INTO SRN MINNESOTA WILL TRAVERSE SE MI BETWEEN 15Z AND
18Z TODAY. MID LEVEL POSITIVE PV ADVECTION WILL BE QUITE STRONG
AHEAD OF THIS WAVE. THERE WILL ALSO BE A POOL OF COLD MID LEVEL
TEMPS WITHIN THIS WAVE, WHICH WILL ACT TO BOOST INVERSION HEIGHTS
AND CONVECTIVE CLOUD DEPTHS. RECENT SATELLITE IMAGERY ALSO SHOWS
SOME MID LEVEL MOISTURE NOW TRACKING FROM IOWA INTO SRN LAKE
MICHIGAN THESE FACTORS WILL SUPPORT AN INCREASE IN LAKE EFFECT SNOW
SHOWER COVERAGE AND INTENSITY THIS MORNING AND INTO EARLY AFTERNOON.
THERE IS AN ONGOING AXIS OF CONVERGENCE OFF LAKE MICHIGAN EXTENDING
INTO SE MI ROUGHLY BETWEEN THE M 59 AND I-69 CORRIDORS. THIS
CONVERGENCE BAND WILL INTENSIFY AS THE LARGER SCALE ASCENT ARRIVES
DURING THE COURSE OF THE MORNING. THE PASSAGE OF THE WAVE WILL VEER
WINDS TO THE NORTHWEST, WHICH WILL DRIVE THE CONVERGENCE AXIS SOUTH
ACROSS METRO DETROIT AND INTO LAKE ERIE IN THE 15Z TO 18Z TIME
FRAME. MODEL SOUNDINGS SUGGEST INVERSION HEIGHTS LIFTING TOWARD 6K
FEET ACROSS THE SOUTHERN HALF OF THE FORECAST AREA THIS MORNING.
GIVEN HOW COLD THE AIRMASS IS WITHIN THE COLUMN, THERE REMAINS VALID
CONCERN THAT THE BETTER ASCENT WILL BE ABOVE THE DENDRITE LAYER.
HOWEVER, IF A MORE ROBUST CONVECTIVE RESPONSE DEVELOPS, LIFT MAY
EASILY EXTEND INTO THE DENDRITIC LAYER. THERE HAS BEEN A SUBTLE
UPTICK IN MODEL QPF AMOUNTS ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA OVER THE LAST 24 HOURS. PATTERN RECOGNITION SUGGESTS THIS EVENT
WILL CERTAINLY BE CAPABLE OF AN AREA OF 2-3 INCH TYPE AMOUNTS WITHIN
ANY QUASI STATIONARY BAND AS REFERENCED IN YESTERDAY'S DISCUSSION.
THE STEEP LOW LEVEL LAPSE RATES ALSO LOOK SUPPORTIVE OF INCH PER
RATES IN THE MORE INTENSE SNOW SHOWERS/SQUALLS. SNOWFALL AMOUNTS
SOUTH OF I-94 WILL BE LESS SIMPLY DUE TO THE EXPECTED TRANSIENT
NATURE OF THE BANDING AS IT GETS SHUNTED SOUTHEASTWARD WITH THE
PASSAGE OF THE UPPER WAVE. AS FOR LOCATIONS NORTH OF I-69, BEING
OUTSIDE OF THE LAKE ENHANCEMENT WILL WARRANT JUST SCATTERED LIGHT
SNOW SHOWERS. IN LIGHT OF THE POTENTIAL INTENSITY OF THE SNOW
SHOWERS/SQUALLS, A WINTER WEATHER ADVISORY WILL BE ISSUED FOR THE
METRO DETROIT/ANN ARBOR AREAS THROUGH MID AFTERNOON. THERE IS
CONCERN THAT THE HIGHER INTENSITY SNOW SHOWER ACTIVITY WILL BE MORE
BRIEF/TRANSIENT ACROSS LENAWEE/MONROE COUNTIES. SO THEY HAVE NOT
BEEN INCLUDED IN THE ADVISORY AT THIS TIME.
STRONG MID LEVEL CONFLUENCE/SUBSIDENCE WILL THEN OVERSPREAD SE MI
DURING THE AFTERNOON/EVENING IN THE WAKE OF THIS WAVE. THE LAKE
AGREGATE MAY SUPPORT A FEW LIGHT SNOW SHOWERS/FLURRIES TONIGHT
MID LEVEL RIDGING WILL THEN EXPAND ACROSS LOWER MI WEDNESDAY
RESULTING IN DRY AND CONTINUED COLD CONDITIONS. AN INBOUND MID LEVEL
SHORT WAVE WED NIGHT AND ASSOCIATED SFC TROUGH WILL RESULT IN A
BACKING OF THE FLOW TOWARD THE SOUTHWEST BY THURS MORNING. THIS WAVE
WILL PROVIDE ANOTHER UPTICK IN LAKE ENHANCEMENT. IN FACT, MODEL
SOUNDINGS SHOW STEEPENING LAPSE RATES AND A POTENTIAL FOR SNOW
SQUALLS DURING THE DAY THURSDAY AS A SURFACE TROUGH PASSES ACROSS SE
MI WHILE LOW LEVEL WINDS VEER TOWARD THE WEST-NORTHWEST.
THE FLOW WILL THEN QUICKLY BACK TO THE SOUTH-SOUTHWEST BY FRIDAY.
THIS AND BUILDING MID LEVEL HEIGHTS WILL RESULT IN A MODEST WARMING
TREND FRIDAY INTO SATURDAY. A SOUTHERN STREAM WAVE WILL THEN OFFER
THE NEXT CHANCE FOR PRECIPITATION OVER THE WEEKEND. ENSEMBLE MEMBERS
CONTINUE TO SHOW A GOOD DEAL OF VARIABILITY WITH RESPECT TO PRECIP
CHANCES AND TYPE AT THIS STAGE IN THE FORECAST. THERE IS HOWEVER
STRONG AGREEMENT AND HIGH CONFIDENCE IN A POLAR LOW OVER CENTRAL
CANADA DRIVING EXTREMELY COLD AIR INTO THE CENTRAL US BY EARLY NEXT
WEEK. THE DEGREE OF COLD AIR SUGGESTS SUB ZERO WIND CHILLS OVER SE
MI AND THE POTENTIAL FOR COLD WEATHER ADVISORIES EARLY NEXT WEEK.
MARINE...
THE COLDEST PUSH OF ARCTIC AIR ARRIVES OVER THE GREAT LAKES THIS
MORNING WHICH WILL SUSTAIN BREEZY CONDITIONS CHARACTERIZED BY WEST
TO NORTHWEST FLOW AROUND 20 KNOTS WITH GUST POTENTIAL AROUND 25
KNOTS, ISOLATED 30 KNOTS. THIS COMBINATION WILL PRODUCE FREEZING
SPRAY ACROSS PORTIONS OF LAKE HURON TODAY. THE ARCTIC AIRMASS WILL
AID IN RE-ICING PORTIONS OF THE OUTER SAGINAW BAY AND AS A RESULT,
WILL PRECLUDE FURTHER ISSUANCE OF SMALL CRAFT ADVISORIES.
A RIDGE OF HIGH PRESSURE WILL THEN BRIEFLY FILL IN OVER THE GREAT
LAKES LATE TONIGHT AND INTO TOMORROW WHICH WILL BRING SOME SLIGHT
REDUCTIONS IN WIND SPEEDS AND GUST POTENTIAL. THE SOUTHERN EXTENSION
OF A CLIPPER SYSTEM WILL MOVE THROUGH THE NORTHERN GREAT LAKES LATE
TOMORROW INTO THURSDAY. WIND DIRECTION BACK FROM WEST-NORTHWEST TO
SOUTHWEST LEADING INTO THURSDAY, BRINGING ENHANCED GUST POTENTIAL
NEARING 30 KNOTS THROUGH THE SAGINAW BAY AND INTO CENTRAL LAKE
HURON WITH THE FAVORABLE FETCH.
DTX WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR MIZ063-
068>070-075-076.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....SF
DISCUSSION...SC
MARINE.......AM
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