597
FXUS63 KDTX 181157
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
657 AM EST SAT JAN 18 2025
KEY MESSAGES
- A TRANSITION FROM RAIN TO A RAIN/SNOW MIX AND EVENTUALLY SNOW
EXPECTED THROUGH THE MORNING HOURS FOR ONGOING PRECIPITATION.
- SNOW ACCUMULATION TOTALS OF A HALF-INCH UP TO AN INCH AND A HALF.
THE HIGHER-END TOTALS WILL BE CONFINED TO THE IRISH HILLS.
- THE COLDEST TEMPERATURES OF THE WINTER THUS FAR ARRIVE EARLY NEXT
WEEK. DANGEROUS WIND CHILLS OF -15 TO -25 LIKELY FOR THE MORNING
HOURS, WITH LITTLE RELIEF FOR THE AFTERNOON, CENTERED MONDAY
THROUGH WEDNESDAY.
AVIATION
A MIX OF RAIN AND SNOW TO ALL SNOW CONTINUES AS A COLD FRONT
FINISHES PASSAGE ACROSS SE MI THIS MORNING. THE TRAILING NNW WIND
SHIFT BEGINS A QUICK DOWNWARD TEMPERATURE TREND BUT ALSO HELPS LIFT
CEILING THROUGH MVFR INTO LOW END VFR BELOW 5000 FT THIS AFTERNOON.
COLD AND DRY NW FLOW CONTINUES TONIGHT WHICH IS FAVORABLE FOR MAINLY
SCATTERED VFR STREAMERS OF STRATOCU WHILE GREATER COVERAGE OF LAKE
EFFECT CLOUDS AND SNOW SHOWERS STAY CLOSER TO LAKE MICHIGAN THROUGH
SUNRISE SUNDAY.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CEILING AOB 5000 FEET THIS MORNING. LOW THIS AFTERNOON
AND TONIGHT.
* HIGH FOR A PRECIPITATION TYPE OF RAIN TRANSITIONING TO A
RAIN/SNOW MIX BEFORE ENDING AS SNOW 12-17Z THIS MORNING.
* LOW FOR CROSSWIND THRESHOLD EXCEEDENCE THIS AFTERNOON.
PREV DISCUSSION
ISSUED AT 326 AM EST SAT JAN 18 2025
DISCUSSION...
AN IMPRESSIVE SURGE OF GULF DERIVED MOISTURE FOR WINTER STANDARDS
HAS FILLED IN ACROSS SE MI, AHEAD OF AN ARCTIC COLD FRONT, WHICH
WILL TRAVERSE OVER THE AREA THIS MORNING. THE INSURGENCE OF HIGHER
THETA-E AIR IS RESPONSIBLE FOR THIS INITIAL COVERAGE OF
PRECIPITATION, WHICH WILL FURTHER GAIN SUPPORT FROM FORCING ALONG
THE FRONT ITSELF, LEADING INTO THE LATE MORNING HOURS. MORNING
TEMPERATURES HAVE INCREASED SEVERAL DEGREES EARLY THIS MORNING, UP TO
+3 TO +4, TIED TO THE WARM AIR ADVECTION. THIS HAS SUPPORTED ALL
RAIN WITH ONSET PRECIPITATION. IT WONT BE UNTIL THE FRONT CATCHES UP
WITH THIS HIGHER THETA-E AIR UNTIL THE TRANSITION TO RAIN/SNOW AND
EVENTUALLY ALL SNOW TAKES PLACE, WHICH LOOKS TO BE CLOSER TO 5-7AM
FOR THE NORTH METRO REGION UP THROUGH FLINT AND PORTIONS OF THE
THUMB, AND CLOSER TO 7AM-9AM FOR THE METRO REGION AND THE LOWER
TERRAIN THROUGH MONROE-WAYNE-MACOMB. THERE WILL BE A NARROW 1-3 HOUR
WINDOW WHERE THE FRONT DOES INTERSECT WITH HIGHER MOISTURE QUALITY
THAT BRINGS SOME ACCUMULATING SNOW POTENTIAL. THESE WARMER
TEMPERATURES WILL CUT INTO SNOWFALL POTENTIAL, HOWEVER, THERE REMAINS
THE POSSIBILITY TO SEE A WET INCH TO INCH AND A HALF FOR HIGHER
TERRAIN WITHIN THE IRISH HILLS, CITING EARLIER PASSAGE OF THE
FRONTAL COUPLED WITH THE COOLER MICROCLIMATE THAT COMES WITH TERRAIN
HEIGHTS. LOCATIONS SOUTHEAST OF THE IRISH HILLS MAY SEE A WET HALF-
INCH, UP TO INCH IN A HIGH-END SCENARIO, PRIOR TO FRONTAL PASSAGE.
LITTLE TO NO ACCUMULATION FOR THE TRI-CITIES, WITH SOME RE-
INVIGORATION OF PRECIP CHANCES ALONG THE FRONT BRINGING SOME LIGHT
SNOW CHANCES FOR THE FLINT AREA UP INTO THE THUMB OVER THE NEXT
SEVERAL HOURS.
TEMPERATURES WILL DECREASE THROUGH THE DAY IN THE WAKE OF THE FRONT,
CAUSING THE WARMEST TEMPERATURES TO BE FELT THIS MORNING.
TEMPERATURES FALL BELOW THE FREEZING MARK ACROSS THE TRI-CITIES
THROUGH THE MID-MORNING HOURS AND THROUGH THE METRO REGION AND THE
REMAINDER OF SE MI BY THE LATE MORNING. RESIDUAL MOISTURE ON
ROADWAYS FROM RAIN OR SNOW THAT MELTS ON CONTACT, MAY FREEZE ON
UNTREATED ROADWAYS, LEADING TO SOME SLICK SPOTS. THE CONTINUED CAA
WILL PUSH TEMPERATURES IN THE TEENS BY LATE THIS EVENING WITH WIND
CHILLS IN THE SINGLE DIGITS.
PASSAGE OF THIS FRONT WILL MARK THE BEGINNING OF THE ADVERTISED
ARCTIC OUTBREAK, WITH THE COLDEST AIR SETTLING OVER THE STATE
THROUGH EARLY NEXT WEEK. THE POLAR JET WILL DRIVE SOUTH INTO THE
PLAINS WHICH WILL DISLODGE POLAR AIR SOUTH THROUGH THE MIDWEST AND
GREAT LAKES ON SUNDAY. BY MONDAY MORNING, H850 TEMPERATURES OF -25C
EXPAND OVER THE STATE, AND CONTINUE TO PLUNGE TO A NOTABLE -28C TO -
30C BY TUESDAY MORNING AND AFTERNOON. IF THESE VALUES VERIFY, THIS
WILL EQUATE TO .5TH TO 1ST PERCENTILE W.R.T CFSR CLIMATOLOGY, OR
ABOUT A 1 DAY EVERY 10 YEAR EVENT WHEN STRICTLY LOOKING AT MODEL
CLIMATOLOGY PER THE GEFS. THIS AIRMASS WILL DROP TEMPERATURE LOWS TO
NEAR 0 EARLY MONDAY MORNING WITH WIND CHILLS IN THE NEGATIVE SINGLE
DIGITS. NO RELIEF WILL BE FELT MONDAY INTO WEDNESDAY MORNING, WHERE
BOTH MONDAY AND TUESDAY FEATURE HIGHS IN THE SINGLE DIGITS AND LOWS
IN THE NEGATIVE SINGLE DIGITS. FACTORING IN WIND CHILLS, APPARENT
TEMPERATURES STAY IN THE NEGATIVES EVEN THROUGH THE AFTERNOON HOURS.
WIND CHILLS DROP TO AROUND -15 TUESDAY MORNING, RISE SLIGHTLY BY
TUESDAY AFTERNOON, AND DROP FURTHER TO AROUND -20 WEDNESDAY MORNING.
ONE OF THE SLIGHT CHANGES NOTED IN THE LATEST OUTPUT WAS THE COLDEST
AIR LINGERING ON LONGER THROUGH WEDNESDAY MORNING, ESPECIALLY
THROUGH THE METRO REGION, WHICH MAY END UP BEING THE COLDEST MORNING
OF THE WEEK. THE ISSUANCE OF AT LEAST A COLD WEATHER ADVISORY WILL
LIKELY BE LEVERAGED THROUGH THE EARLY WEEK PERIOD.
ADVENT OF WELL BELOW NORMAL TEMPERATURES WILL ACTIVATE LAKE MICHIGAN
AND WILL BRING SPORADIC LAKE EFFECT SNOW CHANCES THROUGH THE EARLY
WEEK. BUT AS IT TYPICAL WITH ARCTIC AIRMASSES, DGZ VALUES WELL BELOW
THE CLOUD LAYER WILL MAKE FOR POOR SNOW PRODUCTION AND VERY HIGH
SLRS. MOISTURE DEPTHS WILL BE SHALLOW UP TO 5-7KFT, BUT STRONG LAPSE
RATES WILL SUPPORT SUSTAINMENT OF FLURRIES OR LIGHT SNOW SHOWERS
ACROSS SE MI.
MARINE...
A COLD FRONT TRACKS ACROSS LAKE HURON THIS MORNING, BRINGING A SHIFT
IN WIND DIRECTION TO NORTHWEST AND AREAS OF RAIN AND SNOW THROUGH
THE EARLY AFTERNOON. DRIER, COLD AIR WORKS INTO THE AREA THROUGH THE
DAY WITH NORTHWEST WIND PEAKING IN THE 20 TO 30 KNOT RANGE THIS
AFTERNOON BEFORE WEAKENING SLIGHTLY TONIGHT. LAKE EFFECT SNOW
SHOWERS AND PERIODS OF FREEZING SPRAY WILL ENSUE SUNDAY THROUGH MID
NEXT WEEK AS A FRIGID ARCTIC AIR MASS TAKES RESIDENCE OVER THE GREAT
LAKES. PREVAILING WIND DIRECTION WILL HOLD OUT OF THE NORTHWEST
THROUGH THIS PERIOD, BUT MAY FLUCTUATE LOCALLY AT TIMES AS A LAKE
AGGREGATE SURFACE TROUGH DEVELOPS OVER LAKE HURON. AT THIS TIME WIND
SPEEDS ARE FAVORED TO REMAIN BELOW HEADLINE CRITERIA.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....BT
DISCUSSION...AM
MARINE.......TF
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