066
FXUS63 KDTX 202020
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
320 PM EST MON JAN 20 2025
KEY MESSAGES
- A COLD WEATHER ADVISORY REMAINS IN EFFECT TODAY THROUGH NOON
WEDNESDAY.
- THE COLDEST AIR OF THE WINTER THUS FAR MAKES IT A STRUGGLE FOR
TEMPERATURES TO REMAIN ABOVE ZERO DURING THE DAY AND EASILY REACHES
BELOW ZERO LOWS AT NIGHT THROUGH MID WEEK.
- HAZARDOUS WIND CHILL OF -15 TO -25 F IS ALSO EXPECTED LATE AT
NIGHT AND EARLY IN THE MORNINGS WITH LITTLE RELIEF FOR THE
AFTERNOONS.
- A PERIOD OF GREATER LAKE EFFECT SNOW ORGANIZATION IS POSSIBLE FROM
LATE TODAY INTO EARLY TUESDAY ALONG/BETWEEN THE I-69 TO I-94
CORRIDORS. LIGHT ACCUMULATIONS EXPECTED.
- A MODEST WARMING TREND, ALBEIT STILL BELOW NORMAL, BEGINS THURSDAY
INTO NEXT WEEKEND.
DISCUSSION
INCREASED LAKE MOISTURE FLUX INTO THE AREA THANKS TO DIURNALLY
STRENGTHENED WESTERLY FLOW HAS RESULTED WIDESPREAD STRATOCU
EXPANSION THIS AFTERNOON. EXTREMELY DRY AIRMASS HAS HELPED KEEP LAKE
EFFECT SNOW SHOWER LIMITED IN BOTH COVERAGE AND INTENSITY FOR OUR
SIDE OF THE STATE WITH FLURRIES BEING PROMINENT FOR MOST AREAS. THAT
SAID, THE EXCEPTION HAS BEEN THE WESTERN I-69 CORRIDOR WHERE A
SURFACE CONVERGENCE AXIS FROM ARCTIC AIR WRAPPING AROUND LAKE
MICHIGAN DEVELOPED EARLY THIS AFTERNOON. THIS AXIS IS EXPECTED TO
HOLD LARGELY IN PLACE THROUGH THIS EVENING-EARLY TONIGHT FOCUSING
BEST ACCUMULATING SNOW SHOWERS ALONG/BETWEEN THE I-69/M-59
CORRIDORS. SOUTHWESTERLY FLOW SLACKENS LATE TONIGHT ALLOWING THIS
CONVERGENCE AXIS TO SAG SOUTH TOWARDS THE I-96/I-94 CORRIDORS EARLY
TUESDAY MORNING BEFORE THE DIURNAL MIXING OF THE BOUNDARY LAYER
TAPERS OFF ORGANIZED ACTIVITY AFTER SUNRISE. FLAKE SIZE WILL BE THE
PRIMARY LIMITING FACTOR FOR ACCUMULATION TOTALS WITH SOUNDINGS
ADVERTISING THE BULK OF THE SATURATION LAYER AT OR ABOVE -20C. AS
SUCH, RUNNING FORECAST HASN'T CHANGED TOO MUCH FROM PRIOR CYCLES
WITH A GENERAL 0.5-1" POSSIBLE FOR THE AFOREMENTIONED CORRIDORS.
THOUGH IF ORGANIZED BANDING MANAGES TO LINGER LONGER OVER CERTAIN
LOCATIONS, HIGHER TOTALS AROUND 2" WILL BE POSSIBLE.
MAIN STORY REMAINS THE COLD AIRMASS THAT IS FIRMLY ENTRENCHED ACROSS
THE CENTRAL CONUS. A COLD WEATHER ADVISORY IS STILL IN EFFECT UNTIL
WEDNESDAY MORNING. COLD ADVECTION CONTINUES THROUGH THE NIGHT
LEADING TO WIDESPREAD SUB-ZERO LOWS AND, DESPITE MODEST WEAKENING OF
WINDS, WIND CHILLS IN THE LOW NEGATIVE TEENS. UPPER TROUGH AXIS
CROSSES THE STATE TUESDAY SHIFTING THE CORE OF THE ARCTIC AIRMASS
OVER THE CENTRAL GREAT LAKES/OHIO VALLEY DROPPING 850MB TEMPS TO -
25C TO -28C. SUBSEQUENT HIGHS ONLY RISE INTO THE SINGLE DIGITS WITH
WIND CHILLS STILL IN THE NEGATIVE TEENS. PASSAGE OF THE TROUGH AXIS
SETS UP SOUTHWESTERLY RETURN FLOW TUESDAY NIGHT CUTTING OFF LAKE
MOISTURE FLUX AND ASSOCIATED CLOUD COVER INTO SE MI. SO DESPITE
DEVELOPING LOWER LEVEL WAA THROUGH THE NIGHT, TUESDAY NIGHT LIKELY
IS THE COLDEST NIGHT OF THE WEEK DUE TO EFFICIENT RADIATIVE COOLING
AS LOWS FALL WELL INTO THE NEGATIVE SINGLE DIGITS AND WIND CHILLS
NEARING -20F.
A CLIPPER SYSTEM ARRIVES LATE WEDNESDAY-EARLY THURSDAY BRINGING THE
NEXT CHANCES FOR LIGHT ACCUMULATING SNOWFALL. AS IS TYPICAL WITH
THESE LOWS, CONTINENTAL ORIGIN KEEPS ACCOMPANYING MOISTURE AND
POTENTIAL QPF ON THE LEANER SIDE. MAIN WINDOW FOR ACCUMULATIONS
OCCURS OVERNIGHT WEDNESDAY AS SYSTEM ISENTROPIC ASCENT GETS A BOOST
FROM THE PASSAGE OF THE MID-LEVEL TROUGH BASE OVERHEAD. OVERALL,
FORECAST SNOW TOTALS ONLY EXPECTED TO BE AROUND AN INCH AT BEST.
MAIN ARCTIC AIRMASS BY THIS POINT HAS RETRACTED TOWARD EASTERN
CANADA LIMITING THE MAGNITUDE OF COLD ADVECTION FOLLOWING THE COLD
FROPA DAYTIME THURSDAY (850MB TEMPS ONLY FALL TO AROUND -15C). NEAR
TO ONLY MODERATELY BELOW NORMAL TEMPS ARE FAVORED LATE WEEK/EARLY
NEXT WEEK AS LONG RANGE MODEL SOLUTIONS ADVERTISE A FAIRLY
PERSISTENT LONGWAVE TROUGH LINGERING OVER THE CENTRAL/EASTERN CONUS
THOUGH WITH NO MAJOR ARCTIC INTRUSIONS.
MARINE
AN ADDITIONAL SURGE OF ARCTIC AIR COMBINED WITH HIGH PRESSURE
BUILDING ACROSS THE OHIO VALLEY TODAY CAUSED THE WINDS TO BECOME
WESTERLY AND INCREASE TO 15 TO 25 KNOTS. THE HIGHEST WIND SPEEDS AND
WAVES WILL BE FOUND ACROSS SOUTHERN AND CENTRAL LAKE HURON WHERE
THESE CONDITIONS PLUS THE FRIGID TEMPERATURES WILL RESULT IN AN
EXPANDING AREA OF FREEZING SPRAY. A HEAVY FREEZING SPRAY WARNING
REMAINS IN EFFECT FROM THIS AFTERNOON THROUGH TUESDAY MORNING. A
MARGINAL SMALL CRAFT ADVISORY ALSO REMAINS IN EFFECT FOR THE ICE-
FREE NEARSHORE WATERS FROM OUTER SAGINAW BAY TO HARBOR BEACH.
FREEZING SPRAY AND LAKE EFFECT SNOW SHOWERS CONTINUE THROUGH
WEDNESDAY AS ANOTHER TROUGH ON TUESDAY MORNING USHERS IN THE COLDEST
AIR INTO THE REGION. MODERATE WESTERLY FLOW THROUGH THIS PERIOD
SHIFTS OUT OF THE SOUTHWEST AND STRENGTHENS ON WEDNESDAY, THEN
MILDER AIR SETTLES BACK INTO THE AREA THURSDAY INTO FRIDAY.
PREV DISCUSSION
ISSUED AT 1142 AM EST MON JAN 20 2025
AVIATION...
THE ONSET OF DAYTIME HEATING HAS ALLOWED SOME EASTWARD EXPANSION OF
THE MVFR BASED STRATO CU FROM THE LAKE MICHIGAN MOIST PLUME. SURFACE
OBSERVATIONS AND RECENT HI RES MODEL SOLUTIONS ARE INDICATING A
STRENGTHENING OF LOW LEVEL CONVERGENCE SETTING UP BETWEEN KPTK AND
KFNT. THIS REGION OF LOW LEVEL FORCING IS EXPECTED TO REMAIN NEARLY
STATIONARY THROUGH THE EVENING, SUGGESTING KFNT AND KPTK WILL BE
IMPACTED BY MORE FREQUENT SNOW SHOWERS. GIVEN THE EXTREMELY COLD
AIRMASS, THE SMALL FLAKE SIZE WILL KEEP ACCUMULATIONS UNDER AN INCH.
THE SMALL FLAKES WILL HOWEVER BE GOOD AT OCCASIONALLY REDUCING
VISIBILITIES TO IFR AND LIFR. A MID LEVEL SHORT WAVE WILL TRAVERSE SE
MI OVERNIGHT. THIS WILL OFFER A BETTER OPPORTUNITY FOR SOME
EXPANSION OF THE LAKE STRATO CU PLUME AND SNOW SHOWERS/FLURRIES
ACROSS THE METRO DETROIT TERMINALS.
FOR DTW...WITH THE LOW LEVEL CONVERGENCE AXIS BECOMING ESTABLISHED
FARTHER NORTH, A MORE SOUTHWEST WIND FLOW WILL KEEP THE LAKE
MICHIGAN MOIST PLUME AND THUS SNOW SHOWER ACTIVITY LARGELY NORTH OF
METRO THIS AFTERNOON AND EVENING. A BETTER CHANCE FOR SNOW SHOWER
ACTIVITY WILL ARRIVE WITH THE PASSAGE OF THE SHORT WAVE OVERNIGHT,
WHICH WILL ALSO SUPPORT A SLIGHT BACKING OF THE WINDS TOWARD THE
WEST.
DTW THRESHOLD PROBABILITIES...
* LOW IN CEILINGS AOB 5000 FEET TODAY. MODERATE TONIGHT AND
TUESDAY.
DTX WATCHES/WARNINGS/ADVISORIES
MI...COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR MIZ047>049-
053>055-060>063-068>070-075-076-082-083.
LAKE HURON...HEAVY FREEZING SPRAY WARNING UNTIL 10 AM EST TUESDAY FOR LHZ363-421-
441-462>464.
SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LHZ421-441.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...KDK
MARINE.......DK
AVIATION.....SC
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AT WWW.WEATHER.GOV/DETROIT.
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