451
FXUS63 KDTX 150819
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
319 AM EST WED JAN 15 2025
KEY MESSAGES
- LIGHT SNOW WORKS ACROSS THE AREA BETWEEN 1AM AND 1PM THURSDAY.
ACCUMULATIONS BETWEEN 0.5-1.5" POSSIBLE.
- INCREASING CHANCES FOR PRECIPITATION EARLY SATURDAY. EXACT
PRECIPITATION TYPE, IE HOW MUCH RAIN-SNOW MIX OR ALL SNOW, STILL
UNCERTAIN AT THIS TIME. AT LEAST MINOR ACCUMULATIONS ANTICIPATED.
- HIGH CONFIDENCE IN THE COLDEST AIR OF THE SEASON, THUS FAR,
FOLLOWING FOR SUNDAY THROUGH WEDNESDAY.
- COLDEST DAYS EXPECTED TO BE MONDAY AND TUESDAY WHEN HIGHS STRUGGLE
TO GET ABOVE SINGLE DIGITS WITH OVERNIGHT LOWS BELOW 0. WIND CHILLS
IN THE NEGATIVE SINGLE DIGITS AND TEENS INCREASINGLY LIKELY DURING
THESE DAYS.
DISCUSSION
WHILE A SLIGHT MAJORITY OF THE CWA SAW CLEAR OVERNIGHT SKIES, CLOUDS
MOVE BACK OVER MOST AREAS THIS MORNING AS OHIO VALLEY SURFACE HIGH
PRESSURE SHIFTS LOWER LEVEL FLOW TO THE WEST PUSHING LAKE MICHIGAN
PLUME BACK EAST. WITH THE SATURATION LAYER STILL WITHIN THE DGZ,
FLURRIES ACCOMPANY THESE CLOUDS THROUGH THE FIRST PART OF THE DAY.
INDUCED UPPER RIDGING QUICKLY SLIDES OVER LOWER MI THIS AFTERNOON
SHIFTING LOW LEVEL WINDS TO THE SOUTHWEST. WARM ADVECTION AIDS IN
SCOURING OUT REMNANT LAKE MOISTURE/LOW CLOUD. THE SOUTHERN HALF OF
THE CWA HAS A GOOD SHOT AT SEEING CLEAR SKIES FOR EARLY TONIGHT
SUPPORTING ANOTHER NIGHT WITH LOWS APPROACHING SINGLE DIGITS. ANY
CLEARING IN THE NORTH WILL BE EXTREMELY SHORTLIVED AS A MID-LEVEL
SHORTWAVE DROPPING OUT OF THE CANADIAN PRAIRIE REACHES THE CENTRAL
CENTRAL GREAT LAKES.
SAID CLIPPER SYSTEM OFFERS THE AREA'S NEXT CHANCES TO SEE LIGHT
ACCUMULATING SNOW FOR EARLY THURSDAY. OVERALL, SNOW ACCUMULATIONS
ONLY EXPECTED BE AROUND 0.5-1.5". WHILE LEFT EXIT REGION DYNAMICS OF
THE ASSOCIATED JET STEAK OFFER BETTER UPPER SUPPORT, THE ACTUAL PV
ANOMALY IS PARTIALLY SHEARED AS IT DIGS INTO THE BASE OF THE MID-
UPPER TROUGH REDUCING OVERALL STRENGTH OF ASCENT. LEAD EDGE OF SNOW
SHOWERS, BETWEEN ROUGHLY 2A-7A, LIKELY CARRIES THE HIGHEST RATES
(0.1-0.2"/HR) OWING TO BETTER COHESION OF THE LEAD EDGE OF THE VORT
MAX AND MORE FAVORABLE TIMING TO THE BRIEFLY CATCH/OVERLAP WITH JET
EXIT REGION THAT IS RACING TOWARD THE EASTERN OHIO VALLEY. SHORTWAVE
RAPIDLY TO THE EAST BY LATE AFTERNOON BRINGING AN END TO SYNOPTIC
ACCUMULATING SNOW CHANCES. NW COLD ADVECTION AND MODEST LAKE EFFECT
DEVELOPMENT FOLLOWS LATE DAY THURSDAY OFFERING SCATTERED
FLURRY/LIGHT SNOW SHOWERS CHANCES FOR SE MI, THOUGH NO ACCUMULATIONS
EXPECTED WITH THIS.
LOW AMPLITUDE RIDGING EXPANDS OVER THE GREAT LAKES THURSDAY NIGHT
INTO FRIDAY RESULTING IN DEEPER LAYER SW RETURN SETTING UP INTO
LOWER MI. FAIRLY STRONG WAA DURING THIS TIMEFRAME RAISES 850MB TEMPS
FROM -10C THURS EVENING TO +2C FRIDAY EVENING. HIGHS FRIDAY WILL
REACH BACK TO AROUND NORMAL AT OR A FEW DEGREES ABOVE FREEZING.
SATURDAY ALSO LIKELY SEES SIMILAR HIGHS THOUGH THESE OCCUR IN THE
MORNING AHEAD OF THE NEXT ARCTIC COLD FRONT.
ENSEMBLE FAMILIES (AND DETERMINISTIC 00Z RUNS) CONTINUE TO SUGGEST
FAVORABLE TIMING TO PHASE A NORTHERN STREAM TROUGH OVER THE NORTHERN
GREAT LAKES AND A SOUTHERN STREAM SHORTWAVE LIFTING OUT OF THE
SOUTHERN PLAINS. THIS RESULTS IN AN ACTIVE BAROCLINIC ZONE
DEVELOPING FROM SOUTH CENTRAL IL/IN UP THROUGH SE MI SATURDAY
MORNING AND WIDESPREAD PRECIP FOR THE AREA. WITH THAT SAID, THERE
STILL FINER DETAILS THAT HAVE YET TO BE SORTED OUT. THE MAIN ONE IS
THE TIMING OF THIS PHASING AS THIS DETERMINES WHEN/WHERE THE
BAROCLINIC ACTIVATES. THIS CURRENTLY CARRIES A VARIETY OF OUTCOMES
IN CURRENT DETERMINISTIC RUNS: TOWARDS CENTRAL MI- 00 RGEM, DIRECTLY
OVER SE MI- 00Z ECMWF/GFS, OR JUST TO OUR EAST- 00Z NAM.
ADDITIONALLY THIS TIMING/PLACEMENT ALTERS SPEED OF COLD ADVECTION
INTO LOWER MI AND THE SUBSEQUENT RAIN-SNOW LINE POSITIONING OVER THE
AREA. WORTH NOTING THAT CURRENT TRENDS AMONG LOCAL PROBABILISTIC
GUIDANCE HAS BEEN FAVORING COLDER OUTCOMES (IE MORE SNOW AND LESS
RAIN MIXED IN).
PRECIP CHANCES WITH THIS SYSTEM LOOK TO END BY SATURDAY EVENING WITH
THE PASSAGE OF THE ARCTIC COLD FRONT. HIGH CONFIDENCE IN THIS FRONT
USHERING IN THE COLDEST AIRMASS OF THE SEASON SO FAR AS AMPLIFYING
UPPER TROUGHING OVER THE CENTRAL CONUS BRINGS A -30C AIRMASS OUT OF
NORTHERN CANADA. WHILE THE STILL OPEN LAKES SHIELD THE AREA FROM THE
CORE OF THIS AIRMASS, 850MB TEMPS LOOK TO STILL FALL TO AROUND -25C
MONDAY AND TUESDAY. HIGHS BOTH DAYS LOOKING TO NOT GET OUT OF THE
SINGLE DIGITS WITH OVERNIGHT LOWS IN THE NEGATIVE SIGNAL DIGITS.
WIND CHILLS CURRENTLY FAVORED TO DROP INTO THE NEGATIVE TEENS,
PARTICULARLY TUESDAY MORNING. FOR REFERENCE, THE CRITERIA TO REACH A
COLD WEATHER ADVISORY IS WIND CHILLS AT OR BELOW -15F... WHICH THERE
IS POTENTIAL TO HIT WITH THIS AIRMASS.
MARINE
A RIDGE OF HIGH PRESSURE WILL BRIEFLY FILL IN OVER THE GREAT LAKES
THIS MORNING WHICH WILL MODERATE WIND SPEEDS AND GUST POTENTIAL
THROUGH THE FIRST HALF OF THE DAY. A SOUTHERN EXTENSION OF A CLIPPER
SYSTEM WILL THEN MOVE THROUGH THE NORTHERN GREAT LAKES LATE TONIGHT
INTO TOMORROW MORNING. EXPANSION OF THIS SYSTEM WILL BACK WIND
DIRECTION TO THE SOUTHWEST. THE FAVORABLE FETCH WILL AGAIN PROVIDE A
WINDOW FOR ELEVATED WIND SPEEDS AND GUST POTENTIAL THROUGH THE
SAGINAW BAY AND INTO CENTRAL LAKE HURON, WHERE SUSTAINED WINDS OF 20
TO 25 KNOTS, GUSTS UP TO 30 KNOTS, WILL BE LIKELY. PEAK GUST
POTENTIAL IS EXPECTED EARLY TOMORROW MORNING. THIS SYSTEM ALSO
BRINGS WIDESPREAD LIGHT SNOW TO ALL OF THE GREAT LAKES. PASSAGE OF
THE CLIPPER VEERS WIND DIRECTION BACK TO THE WEST TO NORTHWEST BY
TOMORROW AFTERNOON.
SOUTHWEST WINDS STRENGTHEN FRIDAY AS LOW PRESSURE TRACKS JUST NORTH
OF LAKE SUPERIOR. WHILE WARMER, RELATIVE TO RECENT, AIR IS DRAWN
NORTH, OVERLAKE THERMAL PROFILES CURRENTLY LOOK TO REMAIN NEUTRAL TO
SLIGHTLY UNSTABLE. THIS WOULD SUPPORT THE POTENTIAL FOR AT LEAST
PARTIAL MIXING OF 40KT WIND ALOFT DOWN TOWARD THE SURFACE AND RESULT
IN GUSTS TO GALES OVER THE SOUTHERN AND CENTRAL PORTIONS OF LAKE
HURON. PROBABILITIES TO REACH 34KTS ARE UNUSUALLY HIGH (60-80%) THIS
FAR OUT SO OPTED TO GO AHEAD WITH A GALE WATCH WITH THIS FORECAST
UPDATE FOR FRIDAY AFTERNOON THROUGH EARLY FRIDAY NIGHT.
PREV DISCUSSION
ISSUED AT 1153 PM EST TUE JAN 14 2025
AVIATION...
UPSTREAM SATELLITE TRENDS SUGGEST ONGOING LAKE MOISTURE FLUX WILL
MAINTAIN A HIGHER COVERAGE OF LAKE STRATUS GOING FORWARD OVERNIGHT.
CLOUD BASE WILL REMAIN PRIMARILY AT VFR DURING THIS TIME, WITH SOME
PERIODS OF FLURRIES POSSIBLE. AN INCREASE IN SUBSIDENCE WITH TIME
WILL BRING A DECLINE IN CLOUD BASE ON WEDNESDAY, PROVIDING A WINDOW
FOR SOME MVFR RESTRICTIONS PARTICULARLY DURING THE AFTERNOON AND
EARLY EVENING HOURS. A WARMING LOW LEVEL ENVIRONMENT AS WINDS TURN
TO SOUTHWESTERLY WILL SUPPORT A GRADUAL CLEARING OF LINGERING
STRATUS FROM SOUTH TO NORTH LATE WEDNESDAY, ALTHOUGH WITH LOWER
CONFIDENCE AT MBS. NEXT APPROACHING FRONTAL BOUNDARY WILL BRING AN
AREA OF LIGHT SNOW FOR THE MORNING HOURS THURSDAY.
DTW THRESHOLD PROBABILITIES...
* MEDIUM FOR CIGS AOB 5000 FEET TONIGHT. HIGH WEDNESDAY.
* HIGH FOR PTYPE OF SNOW LATE WEDNESDAY NIGHT AND THURSDAY
MORNING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...GALE WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR
LHZ362-363-421-441-462>464.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...KDK
MARINE.......AM/KDK
AVIATION.....MR
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