646
FXUS63 KDTX 140257
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
957 PM EST MON JAN 13 2025
KEY MESSAGES
- SCATTERED TO NUMEROUS SNOW SHOWERS TONIGHT THROUGH EARLY TUESDAY
AFTERNOON. LOCALIZED ACCUMULATIONS OF 1-3" EXPECTED ALONG AND
BETWEEN THE I-69 AND I-94 CORRIDORS.
- WIND CHILL READINGS OF -5 TO +5 F TUESDAY MORNING, WEDNESDAY
MORNING, AND THURSDAY MORNING.
- COLDEST AIRMASS OF THE WINTER SEASON EXPECTED TO ARRIVE NEXT
MONDAY.
UPDATE
AN INTERESTING LAKE EFFECT SNOW SETUP IS ON SCHEDULE TO ORGANIZE
OVER LOWER MI LATE TONIGHT AND LAST INTO EARLY TUESDAY AFTERNOON.
EVENING SATELLITE IMAGERY SHOWS A STRONG REPRESENTATION OF THE UPPER
MIDWEST MID LEVEL CIRCULATION AND ASSOCIATED BAND OF CLOUDS. RADAR
AND SURFACE OBS ACROSS THE DAKOTAS AND IOWA DO ALSO INDICATE SOME
LIGHT SNOW OR FLURRIES REACHING THE GROUND AS A SIGN THERE IS ENOUGH
SATURATION OCCURING TO SEED LAKE EFFECT SNOW AND HELP OVERCOME UPPER
MIDWEST DRY AIR AS THE SYSTEM REACHES LAKE MICHIGAN. THE WAVE
OTHERWISE CHARGES UP CONVECTIVE DEPTH AND BRINGS AN ORGANIZED
SURFACE PRESSURE REFLECTION THAT STRENGTHENS LOW LEVEL CONVERGENCE
DOWNSTREAM OF THE LAKE. THE ONGOING RELATIVE LULL IN SNOW SHOWER
ACTIVITY GRADUALLY INCREASES COVERAGE AND INTENSITY AS THE LOW
PRESSURE SYSTEM APPROACHES DURING THE NIGHT. A FIRST LOOK AT WIND
TRENDS IN 14/00Z MODEL DATA STILL FAVOR THE AREA GENERALLY SOUTH OF
I-69 AND NORTH OF I-96/696 FOR INITIAL COVERAGE CONSISTING OF
CLUSTERS OR STREAMERS SIMILAR IN CHARACTER TO EARLIER THIS EVENING.
THE MID LEVEL WAVE AND STRENGTHENING SURFACE TROUGH THEN BRING PEAK
ORGANIZATION TOWARD MID MORNING AS CONVERGENCE BECOMES MAXIMIZED
WHILE LOW LEVEL LAPSE RATE SUPPORTS ENTRY LEVEL SNOW SQUALL
INTENSITY. FORTUNATELY BY THIS TIME, THE LARGER SCALE SUPPORTIVE
FEATURES ARE ON THE MOVE AND SO PERSISTENCE OF HIGHER SNOWFALL RATE
BECOMES A LIMITING FACTOR FOR ANY ONE LOCATION. THE STEADY RAMP UP OF
ORGANIZATION OCCURS DURING THE MORNING COMMUTE BUT TRAVEL IS LARGELY
SPARED PEAK INTENSITY REACHED BY MID MORNING. THE PROGRESSIVE NATURE
OF THE FOCUSING SURFACE TROUGH THEN LIMITS POTENTIAL FOR
OVERACHIEVEMENT OF TOTAL ACCUMULATION WHICH HOLDS BELOW 3"/6HR TO
4"/12 HR ADVISORY THRESHOLDS AS THE FRONT EXITS INTO ONTARIO/OHIO BY
EARLY AFTERNOON.
PREV DISCUSSION
ISSUED AT 657 PM EST MON JAN 13 2025
AVIATION...
LOCALIZED CONVERGENCE IN THE LOW LEVEL WIND FIELD COMBINED WITH
DAYTIME BOUNDARY LAYER INSTABILITY TO HELP LAKE EFFECT SNOW SHOWERS
FLARE UP INTO SE MI DURING LATE AFTERNOON. THIS CONTINUES TO MAINLY
AFFECT THE FNT TO PTK CORRIDOR WITH BRIEF IFR VISIBILITY AND MVFR
CEILING UNTIL DROPPING BACK TO FLURRIES THIS EVENING. BREAKS IN THE
CLOUD COVER TOWARD MBS ALSO FILL BACK IN AT MVFR DURING THE EVENING
AND THEN CONDITIONS HOLD ACROSS SE MI UNTIL BANDS OF LAKE EFFECT
SNOW ORGANIZE LATER TONIGHT THROUGH TUESDAY MORNING. THE SNOW BANDS
INITIALLY MOVE INTO THE FNT TO PTK AREA AFTER 08Z AND BRING
BORDERLINE IFR/LIFR INTENSITY TOWARD SUNRISE UNTIL MOVING SOUTHWARD
TOWARD THE DTW CORRIDOR FROM MID TO LATE MORNING. THE RESPONSIBLE
MID LEVEL WAVE PRODUCES A DUAL COLD FRONT ACROSS LOWER MI, THE FIRST
OF WHICH SWEEPS THE SNOW SHOWERS INTO ONTARIO/OHIO EARLY IN THE
AFTERNOON AND THE SECOND BRINGS A SHORTER AND LESS INTENSE PERIOD OF
SNOW SHOWERS THAT MAY NOT EVEN MAKE IT TO THE DTW CORRIDOR BEFORE
LOW LEVEL WIND SHIFTS MORE UNIFORM WESTERLY INTO TUESDAY EVENING.
FOR DTW... A STRAY SNOW SHOWER THIS EVENING GIVES WAY TO JUST
FLURRIES FOR THE BULK OF TONIGHT. CONDITIONS THEN ORGANIZE FOR
STRONGER BANDS OF LAKE EFFECT SNOW TUESDAY MORNING. A LATE MORNING
PEAK IN COVERAGE AND INTENSITY IS EXPECTED WHICH COULD PRODUCE
AROUND 1 INCH OF ACCUMULATION.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CEILING 5000 FEET OR LESS TONIGHT AND TUESDAY.
PREV DISCUSSION...
ISSUED AT 321 PM EST MON JAN 13 2025
DISCUSSION...
STRONG PV ANOMALY ROTATING THROUGH NORTHERN MINNESOTA THIS AFTERNOON
AND THROUGH SOUTHERN LOWER MICHIGAN TOMORROW, SHEARING OUT IN THE
PROCESS HOWEVER. THIS SYSTEM AND UPPER LEVEL TROUGH WILL PROVIDE
UPPER LEVEL SUPPORT TO ENHANCE LAKE EFFECT SNOW SHOWERS, WITH
POTENTIAL SEEDER-FEEDER MECHANISM BUT MORE LIKELY JUST INCREASE IN
INVERSION DEPTHS 7+ KFT. HOWEVER,THE AIRMASS IS SO COLD AND DRY (~
-10 F DEW PTS IN WISCONSIN TONIGHT), TOUGH TO GAUGE JUST HOW STRONG
THE WESTERLY BAND OR BANDS IN BETWEEN I-69 TO I-94 WILL BE TONIGHT
INTO TUESDAY MORNING, AS THE MODEST CAPE/STEEP LOW LEVEL LAPSE RATES
MAY ACTUALLY END UP BEING JUST ABOVE THE DGZ (SEE NAM SOUNDINGS), AS
850 MB TEMPS PLUMMET INTO THE NEGATIVE LOWER 20S. ON THE FLIP SIDE,
IF SOME OF THE CAPE/LIFT RESIDES IN THE DGZ, THE FLUFF FACTOR WILL
BE EXTREMELY HIGH, AND IF REGIONAL GEM SOLUTION VERIFIES, 0.05
INCHES OF QPF EASILY BECOMES 2+ INCHES OF SNOW. ITS ALSO UNKNOWN HOW
PERSISTENT THE BAND(S) WILL BE AND WHETHER THEY WILL BE TRANSIENT
ENOUGH TO HELP LIMIT AMOUNTS. ULTIMATELY, PREFERENCE IS TO HIGHLIGHT
LOCALIZED 1-3" AMOUNTS OF FLUFFY SNOW ALONG/IN BETWEEN THE
I-69/I-94 CORRIDORS. EVEN THIS AFTERNOON'S ACTIVITY HAS OVERACHIEVED
A BIT, WITH FLINT RECEIVING 4 TENTHS OF AN INCH THROUGH 18Z.
SURFACE TROUGH SWINGING SOUTH FROM NORTHERN LOWER MICHIGAN IN THE
AFTERNOON MAY TOUGH OFF SOME ADDITIONAL SNOW SHOWER ACTIVITY, BUT
GENERAL SUBSIDENCE KICKING IN AND 850 MB TEMPS WARMING INTO NEGATIVE
MID TEENS BY EVENING. DESPITE THE NORTHWEST FLOW, CAN'T RULE OUT
FLURRIES AND ISOLATE SNOW SHOWERS TRACKING THROUGH TOMORROW NIGHT,
AS THERE IS STILL SATURATION WITH RESPECT TO ICE NOTED IN THE 1-3
KFT LAYER. ON FLIP SIDE, WOULD EXPECT SOME POCKETS/STREAKS OF
CLEARING AS WELL, AND WILL FAVOR COLDER MINS IN THE 10 TO 15 DEGREE,
BUT POTENTIAL FOR NORMALLY COLDER SITES TO DIP INTO THE SINGLE
NUMBERS WITH THE FRESH SNOW.
SHORT LIVED RIDGING DURING THE DAY ON WEDNESDAY BEFORE ANOTHER
SHORTWAVE/500 MB TROUGH TRACKS THROUGH WEDNESDAY NIGHT/THURSDAY
MORNING. MOISTURE AXIS FROM THE MIDWEST TENDING TO GET PINCHED OFF,
THUS JUST CHANCE POPS, AS AIRMASS IS ALSO NOT TERRIBLY COLD WITH 850
MB TEMPS IN THE NEGATIVE HIGH SINGLE NUMBERS.
STRONG WARM ADVECTION PATTERN FOLLOWS TO END THE WORK WEEK BEFORE A
MAJOR COLD BLAST ARRIVES OVER THE WEEKEND, AS FULL FLEDGED NORTH
AMERICAN TROUGH DEVELOPS AND LINGERS INTO NEXT WEEK. 850 MB TEMPS
AOB -25 C FORECASTED BY EURO/GFS ON MONDAY, MAKING THIS AIRMASS THE
COLDEST OF THE WINTER SEASON BY FAR.
MARINE...
BREEZY CONDITIONS CONTINUE UNDER THE BACKDROP OF COLD AIR ADVECTION
WHICH WILL MAINTAIN SUSTAINED WEST FLOW OF 20 TO 25 KNOTS, WITH GUST
POTENTIAL HOLDING JUST SHY OF 30 KNOTS. THE LATEST ICE ANALYSIS
SHOWS PORTIONS OF THE OUTER SAGINAW BAY THAT REMAIN ICE FREE, THUS
SMALL CRAFT ADVISORIES WILL CONTINUE GIVEN WAVE HEIGHT POTENTIAL
NEARING THE FOUR FT. THRESHOLD. PORTIONS OF THE OPEN WATER FROM PORT
AUSTIN DOWN NEAR PORT HOPE ALSO MAY HAVE SOME ICE FREE ZONES AWAY
FROM THE SHORELINE WHICH CAN SEE SOME ELEVATED WAVE HEIGHTS, BUT THE
MAJORITY OF THE NEARSHORE ZONE HAS SOME DEGREE OF ICE, SO THE
DECISION WAS MADE OVERNIGHT TO DROP THE ONGOING SMALL CRAFT
ADVISORY. WIND DIRECTION WILL VEER TO THE NORTHWEST TOMORROW AS EVEN
COLDER AIR DROPS IN ACROSS THE GREAT LAKES. THIS WILL SUSTAIN BREEZY
CONDITIONS THROUGH WEDNESDAY MORNING, WHERE A BRIEF RIDGE OF HIGH
PRESSURE THEN DECREASES WIND INTENSITY. SNOW SHOWERS REMAIN POSSIBLE
WITH THE CONTINUED COLD.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LHZ421.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...LOW WATER ADVISORY UNTIL 1 PM EST TUESDAY FOR LEZ444.
UPDATE.......BT
AVIATION.....BT
DISCUSSION...SF
MARINE.......AM
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AT WWW.WEATHER.GOV/DETROIT.
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