140
FXUS63 KDTX 192101 CCA
AFDDTX
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
401 PM EST SUN JAN 19 2025
KEY MESSAGES
- ARCTIC AIR GAINS GROUND ACROSS THE GREAT LAKES WITH NEARLY
STEADY TEMPERATURES IN THE TEENS TODAY AND SINGLE DIGIT LOWS
TONIGHT.
- THE COLDEST TEMPERATURES OF THE WINTER THUS FAR THEN ARRIVE
MONDAY THROUGH WEDNESDAY. AIR TEMPERATURE STRUGGLES TO REMAIN
ABOVE ZERO DURING THE DAY AND EASILY REACHES BELOW ZERO LOWS AT
NIGHT.
- HAZARDOUS WIND CHILL OF -15 TO -25 F IS ALSO EXPECTED LATE AT IGHT
AND EARLY IN THE MORNING WITH LITTLE RELIEF FOR THE AFTERNOON.
- A PERIOD OF GREATER LAKE EFFECT SNOW ORGANIZATION IS POSSIBLE LATER
MONDAY INTO EARLY TUESDAY.
- A MODEST WARMING TREND BEGINS THURSDAY INTO NEXT WEEKEND.
DISCUSSION
CONTINENTAL ARCTIC AIR MASS, 12Z 850MB RAOB TEMPERATURES OF -21.9C
AND -25.9C AT KGRB AND KAPX RESPECTIVELY, IS NOW INFILTRATING INTO
SOUTHEAST MICHIGAN THIS AFTERNOON. THE COLD FRONT IS BISECTING THE
CWA AROUND THE M 59 CORRIDOR AT MIDDAY WITH A SURFACE DEWPOINT
DIFFERENCE OF SOME 10 DEGREE F ACROSS THE FRONT. BEEN OBSERVING VERY
LIGHT SNOW ACTIVITY IN A CONVERGENCE AXIS AHEAD OF THE FRONT THAT IS
STEADILY PUSHING TO THE SOUTHEAST. FOR THE REMAINDER OF THE DAYLIGHT
HOURS THIS AFTERNOON, FORECAST SOUNDINGS SUPPORT A RESPECTABLE
AMOUNT OF SUPERSATURATION WITH RESPECT TO ICE THROUGH THE DENDRITIC
GROWTH ZONE FROM THE SURFACE THROUGH APPROXIMATELY 6.0 FT AGL.
SYNOPTICALLY, A NICE LITTLE SIGNAL FOR CONTINUED LIGHT SNOW SHOWER
ACTIVITY WITH ABSOLUTE VORTICITY LOBE PROVIDING FOR SOME WEAK
MIDLEVEL ISENTROPIC LIFT AND ICE CRYSTAL SEEDING. MAJOR LIMITATIONS
ON ACTIVITY THIS AFTERNOON ARE THE VERY LOW ABSOLUTE MOISTURE OF
1000-850MB SPECIFIC HUMIDITIES OF 1-1.5 G/KG AND VIRTUALLY NO NBM
FORECASTED LIQUID EQUIVALENT.
COLD AIR ADVECTION WILL OCCUR ACROSS SOUTHEAST MICHIGAN THIS EVENING
AND TONIGHT WITH 850MB TEMPERATURES DROPPING DOWN TO -23C TO -24C.
STEEPENING OF NEAR SURFACE LAPSE RATES WILL RESULT IN A DECENT MIXED
ENVIRONMENT, GOOD FOR A MODEST SUSTAINED WEST WIND MONDAY MORNING.
FORECASTED WIND CHILLS OF -12C TO -18C ARE EXPECTED AROUND DAYBREAK
MONDAY WITH THE COLDEST CONDITIONS NEAR THE OHIO VALLEY. PER
COORDINATION WITH SURROUNDING OFFICES AND THE VARIANCE IN
FORECASTING LOCAL WINDSPEEDS AND TEMPERATURES, THE DECISION WAS MADE
TO BEGIN THE COLD WEATHER ADVISORY TONIGHT AT MIDNIGHT.
THE MAIN COMPOSITE TROUGH AXIS WILL APPROACH THE CENTRAL GREAT LAKES
DURING THE DAY ON MONDAY WITH THE LEAD EDGE TO GREATER ABSOLUTE
VORTICITY SPREADING ACROSS THE LOWER PENINSULA. MODELS HAVE BEEN
CONSISTENT IN THE DIFFERENTIAL CYCLONIC VORTICITY BREAKING OFF SOME
LAKE SCALE CONVERGENCE/MOISTURE/LAKE EFFECT FROM LAKE MICHIGAN AND
SENDING IT EASTWARD. OUT OF RESPECT FOR THE WIND CONVERGENCE ALONG
THE I 96 AND M 59 CORRIDORS DID INCREASE POPS INTO THE LIKELY
CATEGORY MONDAY AFTERNOON AND EVENING. MAJOR LIMITATIONS ON
PRECIPITATION AMOUNTS IS EXPECTED THIS FAR REMOVED FROM LAKE
MICHIGAN, HOWEVER, AS VERY UNFAVORABLE MICROPHYSICS WILL EXIST GIVEN
THE COLD SOUNDING AND VERY LEAN ABSOLUTE MOISTURE. FOR MANY
LOCATIONS, NOT MUCH OF A DUSTING IS POSSIBLE BUT LONGER DURATION
SNOW ACCUMULATIONS OF LESS THAN AN INCH MAY BE POSSIBLE IN ANY
PERSISTENT BANDING.
COLDEST AIR MASS BUILDS INTO THE REGION FOR TUESDAY AND EARLY
WEDNESDAY. LOWS ARE EXPECTED TO BOTTOM OUT IN THE SINGLE DIGITS
BELOW ZERO FOR BOTH MORNINGS, WHICH DEPENDING ON THE LOCATION IS
SOME 15 TO 25 DEGREES BELOW NORMAL. RECORD TEMPERATURES ARE NOT
EXPECTED TO BE CHALLENGED DURING THIS TIME PERIOD. THE COLD WEATHER
ADVISORY WILL REMAIN IN EFFECT THROUGH NOON WEDNESDAY.
DESPITE PERSISTENT TROUGHING OVER THE GREAT LAKES, RISING
GEOPOTENTIAL HEIGHTS WILL ALLOW TEMPERATURES TO MODERATE DURING THE
END OF THE WEEK AND NEXT WEEKEND. DAYTIME TEMPERATURES ARE EXPECTED
TO BE MAINLY IN THE 20S. NO MAJOR PRECIPITATION SYSTEMS ARE
ANTICIPATED FROM THIS VANTAGE POINT.
MARINE
NORTHWEST FLOW AROUND 10 TO 15 KNOTS DOMINATES MOST OF THE REGION
THIS AFTERNOON WITH FLOW VEERING TO NORTHERLY ACROSS PARTS OF
NORTHERN AND CENTRAL LAKE HURON BEHIND A SURFACE TROUGH SINKING
SOUTHWARD. A LOCALIZED SNOW BAND WILL ACCOMPANY THIS TROUGH THROUGH
TONIGHT. A FRESH SURGE OF COLD ARCTIC AIR WILL CAUSE WINDS TO SHIFT
TO WESTERLY ON MONDAY, WITH WIND SPEEDS INCREASING TO THE 15 TO 25
KNOT RANGE. ICE COVERAGE IN THE LATEST ANALYSIS IS SPARSE ACROSS
PARTS OF THE LAKE HURON NEARSHORE, SO OPTED TO ISSUE A SMALL CRAFT
ADVISORY FOR 4+ FOOT WAVES FROM OUTER SAGINAW BAY TO HARBOR BEACH
TONIGHT INTO TUESDAY. FREEZING SPRAY IS EXPECTED TO INCREASE IN
INTENSITY ACROSS CENTRAL AND SOUTHERN LAKE HURON THROUGH THE DAY
TOMORROW, BECOMING HEAVY BY THE LATE AFTERNOON AND EVENING. A HEAVY
FREEZING SPRAY WARNING IS NOW IN EFFECT FOR THESE AREAS. FREEZING
SPRAY AND LAKE EFFECT SNOW CONTINUE THROUGH WEDNESDAY AS THE COLDEST
AIR HOLDS IN PLACE. MILDER AIR THEN WORKS BACK INTO THE AREA
THURSDAY INTO FRIDAY AMIDST MODERATE SOUTHWEST FLOW.
PREV DISCUSSION
ISSUED AT 103 PM EST SUN JAN 19 2025
AVIATION...
LOW VFR TO OCCASIONAL MVFR CIGS PERSIST THROUGH THE AFTERNOON AND
EVENING AS MOISTURE STREAMS OFF OF LAKE MICHIGAN INTO THE AIRSPACE.
COMBINATION OF HIGH CLOUD AND LAKE CLOUD HAS PROVIDED JUST ENOUGH
MOISTURE TO SQUEEZE OUT SOME FLURRIES/LIGHT SNOW SHOWERS WHICH ARE
ONGOING FROM PTK TO DTW AT ISSUANCE. OCCASIONAL VSBY DROPS TO IFR
HAVE BEEN OBSERVED. INBOUND COLD ARCTIC AIRMASS KEEPS LAKE MICHIGAN
ACTIVE TONIGHT AS AN UPPER LEVEL WAVE BRINGS ANOTHER PLUME OF LAKE
EFFECT SNOW SHOWERS OVERHEAD BETWEEN 21Z AND 03Z TONIGHT. BY MONDAY
MORNING, EVEN COLDER TEMPERATURES AND BACKING OF WINDS FROM CURRENT
NW DIRECTION TO W WILL RESULT IN DIFFUSE BANDS OF LAKE EFFECT SNOW
GENERALLY BETWEEN DTW AND FNT FOR MOST OF THE DAY MONDAY. A DUSTING
OF NEW ACCUMULATION WILL BE POSSIBLE BY THE END OF THE TAF PERIOD
MONDAY. THE DRY NATURE OF THE SNOW WILL BE SUSCEPTIBLE TO BLOWING
AROUND AS WIND GUSTS INCREASE TO 20-25 KNOTS, ALTHOUGH WITH LIMITED
ACCUMULATION POTENTIAL DO NOT EXPECT MUCH IF ANY RESTRICTION TO
VSBYS FROM BLSN.
DTW THRESHOLD PROBABILITIES...
* MODERATE FOR CEILING AOB 5000 FEET THROUGH EVENING, LOW TONIGHT,
MODERATE AGAIN ON MONDAY.
* P-TYPE WILL BE ALL SNOW FOR THE TAF PERIOD.
DTX WATCHES/WARNINGS/ADVISORIES
MI...COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
WEDNESDAY FOR MIZ047>049-053>055-060>063-068>070-075-076-082-
083.
LAKE HURON...HEAVY FREEZING SPRAY WARNING FROM 4 PM MONDAY TO 10 AM EST TUESDAY
FOR LHZ363-421-441-462>464.
SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 4 PM EST TUESDAY FOR
LHZ421-441.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...CB
MARINE.......TF
AVIATION.....MV
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