241
FXUS63 KDTX 171203
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
703 AM EST FRI JAN 17 2025
KEY MESSAGES
- WIDESPREAD RAIN/SNOW TO SNOW EXPECTED SATURDAY MORNING. SNOW
ACCUMULATION TOTALS OF A HALF-INCH UP TO 2 INCHES LIKELY, WITH
HIGHER-END AMOUNTS FAVORED WITHIN 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
EXPANSIVE LOW PRESSURE FROM NORTHERN ONTARIO TO TEXAS PRODUCES A
STRENGTHENING SOUTH WIND ACROSS LOWER MI TODAY. THIS FIRST DISPLACES
LOW CLOUDS FROM SE MI THIS MORNING AND BRINGS WARMER AIR INTO THE
REGION AS SOUTH WIND BUILDS TO GUSTS NEAR 30 KNOTS. VFR BROKEN HIGH
CLOUDS THEN THICKEN AND LOWER THIS EVENING AS A BAND OF RAIN/SNOW
MIX MOVES FROM THE MID MS VALLEY INTO LOWER MI TOWARD MIDNIGHT. A
RAPID DECREASE TO MVFR OCCURS WITH PRECIPITATION ONSET TRENDING TO
IFR RESTRICTION AS THE MIX CHANGES TO SNOW JUST PRIOR TO THE COLD
FRONT PASSAGE. MVFR CLOUDS AND SNOW LINGER FOR A FEW HOURS AFTER THE
NW WIND SHIFT INTO SATURDAY MORNING.
DTW THRESHOLD PROBABILITIES...
* LOW FOR CEILING AOB 5000 FEET TODAY. HIGH TONIGHT.
* MEDIUM FOR A PRECIPITATION TYPE OF RAIN AND MELTING SNOW AT
ONSET AFTER 06Z TONIGHT. HIGH FOR ALL SNOW POST FRONT LATE
TONIGHT INTO SATURDAY MORNING.
PREV DISCUSSION
ISSUED AT 343 AM EST FRI JAN 17 2025
DISCUSSION...
A SHORTWAVE RIDGE UNDER BACKED FLOW WILL BRING A DAY OF DRY WEATHER
AND INCREASING TEMPERATURE TRENDS WITH MORNING HIGHS IN THE LOW 30S
ON TRACK TO PEAK INTO THE MID TO UPPER 30S TODAY. BIG CHANGES ARE IN
STORE ONCE A POLAR AIRMASS DRIVES SOUTH INTO THE GREAT LAKES EARLY
NEXT WEEK, BRINGING THE COLDEST AIR OF THE WINTER THUS FAR.
POSITIVE THETA-E ADVECTION WILL TAKE PLACE ALONG THE CYCLONICALLY
SHEARED SIDE OF A WANING LLJ, ORIENTED ALONG LAKE ERIE THROUGH
QUEBEC, AND UPSTREAM OF AN APPROACHING ARCTIC COLD FRONT TONIGHT.
PRECIPITATION QUICKLY DEVELOPS AND FILLS IN ACROSS THE GREATER
PORTION OF THE CWA AROUND/AFTER MIDNIGHT AS MOIST ISENTROPIC ASCENT
COMMENCES. THIS MOISTURE ADVECTION WILL BE ACCOMPANIED BY A MODEST
DEGREE OF WAA. TEMPERATURES PRIOR TO THE ADVENT OF PRECIPITATION ARE
FORECASTED TO RESIDE AROUND THE 32-35 DEGREE MARK, AND MAY
APPRECIATE A DEGREE WITH THE INITIAL START OF PRECIPITATION, THUS A
WINTRY MIX/MELTING SNOW WILL BE THE LIKELY P-TYPE WITHIN THE IRISH
HILLS/GLACIAL RIDGE, WITH LOCATIONS SOUTHEAST THROUGH THE METRO
REGION SHOWCASING HIGH PROBABILITIES TO START AS RAIN OR A WINTRY
MIX. THE APPROACHING COLD FRONT WILL THEN SUSTAIN PRECIPITATION
THROUGH THE MID TO LATE MORNING HOURS, DRIVING A TRANSITION TO ALL
SNOW FOR SEVERAL HOURS, WITH SNOW ENDING BY THE LATE MORNING TO
EARLY AFTERNOON HOURS.
SNOW TOTALS WILL BE HIGHLY SENSITIVE TO THE DEGREE OF INITIAL WAA
AND TIMING OF THE COLD FRONT (TRANSITION WINDOW FOR ALL SNOW). THE
IRISH HILLS/GLACIAL RIDGE WILL LIKELY SEE THE HIGHER END TOTALS
GIVEN THE RESIDENCE TIME OF BETTER LIQUID EQUIVALENT TOTALS
OVERLAPPING THE COOLER TEMPERATURE PROFILES AND EARLIER ARRIVAL OF
THE COLD FRONT. AN INCH, UP TO TWO INCHES, WILL BE POSSIBLE BY THE
LATE MORNING HOURS. PORTIONS OF MACOMB, WAYNE, AND MONROE OUTSIDE OF
THE IRISH HILLS MAY STRUGGLE TO SEE ANYTHING OVER THAN AN INCH,
CITING P-TYPE CONCERNS. THE TRI-CITIES WILL SEE VERY LITTLE TO NO
QPF AS ITS REMOVED FROM THE MOISTURE AXIS, AND THESE LOW END AMOUNTS
MAY EVEN EXTEND INTO PORTIONS OF THE WESTERN THUMB AND POSSIBLY
FARTHER SOUTHEAST THAN CURRENTLY PROJECTED (SEE LATEST ARW). COLD
AIR ADVECTION IN THE WAKE OF THE FRONT WILL DROP TEMPERATURES BELOW
FREEZING THROUGH THE DAY, SO RESIDUAL MOISTURE ON UNTREATED ROADWAYS
MAY FREEZE OVER AND PRODUCE SLICK SPOTS. THE WARMEST TEMPERATURES
WILL BE FELT IN THE MORNING HOURS WITH TEMPERATURES PLUMMETING IN
THE LOW 20S BY THE LATE EVENING TOMORROW. WIND CHILLS START TO
APPROACH THE SINGLE DIGITS AROUND THIS TIME FACTORING IN SLIGHTLY
BREEZY CONDITIONS WITH GUST POTENTIAL AROUND 20-25 MPH.
THE MUCH ADVERTISED ARCTIC OUTBREAK REMAINS ON TRACK TO IMPACT SE MI
THROUGH THE EARLY WEEK PERIOD. IN THE WAKE OF THE AFOREMENTIONED
ARCTIC COLD FRONT, THE POLAR JET WILL WILL EXTEND THROUGH THE
PLAINS THIS WEEKEND. POLAR AIR BECOMES DISPLACED AND FILLS IN ACROSS
THE MIDWEST ON SUNDAY, BRINGING THE INITIAL PUSH OF ARCTIC AIR,
CAPPING HIGHS IN THE TEENS. THE COLDEST PUSH OF AIR ENTERS MONDAY
INTO TUESDAY, AS H850 TEMPERATURES RANGING BETWEEN -25 TO -28 FILLS
IN OVERHEAD. PER GEFS M-CLIMATE ANALYSIS, AIR MASSES OF THIS NATURE
FILL IN OVER THE GREAT LAKES ABOUT ONCE EVERY 10 YEARS. THIS WILL
DROP TEMPERATURE LOWS TO ABOUT 0 DEGREES MONDAY MORNING WITH WIND
CHILLS AROUND -10 TO -15F. HIGH TEMPERATURES MONDAY STAY CAPPED IN
THE HIGH SINGLE DIGITS, BEFORE THE COLDEST PUSH OF ARCTIC AIR DROPS
LOWS TO -5 TO -10F TUESDAY MORNING, WIND CHILLS
-15 TO -20F. NO RELIEF WILL BE FELT TUESDAY AFTERNOON WITH HIGHS IN
THE MID SINGLE DIGITS AND WEDNESDAY MORNING LOWS BACK IN THE
NEGATIVE SINGLE DIGITS WITH WIND CHILLS OF -20F. THIS OUTBREAK HAS
THE FULL WEIGHT OF THE ENSEMBLES BACKING IT AND IS AN EXTREMELY HIGH
CONFIDENCE EVENT. COLD WEATHER ADVISORIES AT A MINIMUM WILL BE
LIKELY. RELIEF FROM THE ARCTIC OUTBREAK STARTS WEDNESDAY ONCE RETURN
FLOW FROM AN OHIO RIVER VALLEY HIGH FLIPS FLOW TO THE SOUTHWEST,
ADVECTING WARMER TEMPERATURES. HIGHS IN THE TEENS WEDNESDAY INCREASE
INTO THE 20S FOR THE END-WEEK PERIOD.
PERIODS OF LAKE EFFECT FLURRIES TO LIGHT SNOW SHOWERS WILL BE LIKELY
WITH THE ARCTIC AIR, BUT AS IT COMMON WITH THESE TEMPERATURES, SNOW
PRODUCTION WILL BE POOR CITING DGZS BELOW THE CLOUD LAYER. HAVE
INCLUDED LOW CHANCE POPS (20%) AT THIS TIME FOR MONDAY AND TUESDAY
DAYLIGHT HOURS, COINCIDING WITH BETTER LLLR UNDER DIURNAL HEATING.
MARINE...
A BRIEF LULL IN WIND MAGNITUDE EARLY THIS MORNING GIVES WAY TO
RAPIDLY INCREASING SOUTHERLY WIND THIS AFTERNOON AS A STRONG LOW
PRESSURE SYSTEM TRACKS JUST NORTH OF LAKE SUPERIOR. HIGH CONFIDENCE
EXISTS FOR GALES ACROSS MOST OF LAKE HURON THIS AFTERNOON INTO
TONIGHT, WITH MODERATE CONFIDENCE IN GUSTS TO 40+ KNOTS THIS
EVENING. A GALE WARNING REMAINS IN EFFECT THROUGH EARLY SATURDAY
MORNING. PASSAGE OF THE SYSTEM'S COLD FRONT BRINGS SNOW, POSSIBLY
MIXED WITH SOME RAIN, SATURDAY MORNING. FOLLOWING THE FRONT,
NORTHWEST WIND INCREASES TO THE 20 TO 25 KNOT RANGE SATURDAY
AFTERNOON AND EVENING. A FRIGID ARCTIC AIR MASS WILL WORK INTO THE
REGION THIS WEEKEND AND PERSIST THROUGH EARLY NEXT WEEK, BRINGING
LIKELY LAKE EFFECT SNOW SHOWERS AND POTENTIAL FOR FREEZING SPRAY.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...GALE WARNING FROM NOON TODAY TO 4 AM EST SATURDAY FOR LHZ362-363-
421-441-462>464.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....BT
DISCUSSION...AM
MARINE.......TF
CLIMATE......AM
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