839
FXUS63 KDTX 201642
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1142 AM 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 MORNING WITH LITTLE RELIEF FOR THE
AFTERNOON.
- A PERIOD OF GREATER LAKE EFFECT SNOW ORGANIZATION IS POSSIBLE FROM
LATE TODAY INTO EARLY TUESDAY.
- A MODEST WARMING TREND BEGINS THURSDAY INTO NEXT WEEKEND.
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.
PREV DISCUSSION
ISSUED AT 358 AM EST MON JAN 20 2025
DISCUSSION...
DECREASING TEMPERATURE TRENDS ARE ON OR AHEAD OF SCHEDULE ACROSS
LOWER MI SINCE MIDNIGHT. READINGS WELL DOWN INTO THE SINGLE DIGITS TO
NEAR ZERO ARE ENABLED BY CLEAR SKY FOR THE MAJORITY OF LOCATIONS
WHICH IS ALSO KEEPING WIND SPEED IN CHECK WITH SOME FRAGILE BOUNDARY
LAYER STABILITY. AN UPTICK IN SPEED OCCURS WITH SUNRISE WHILE
TEMPERATURES ARE IN THE 0 TO +5 F RANGE FOR WIND CHILL REACHING THE
-15 F COLD WEATHER ADVISORY THRESHOLD FOR A FEW HOURS, ESPECIALLY
TOWARD THE OHIO BORDER WHERE DIRECTION IS BACKING SLIGHTLY SW FOR
LESS BUFFERING FROM THE GREAT LAKES. AIR TEMPERATURES RECOVER DURING
THE DAY BUT STRUGGLE TO REACH +10 F, JUST ENOUGH FOR WIND CHILL TO
AVERAGE SINGLE DIGITS BELOW ZERO THIS AFTERNOON. THE COLD WEATHER
ADVISORY WILL REMAIN IN EFFECT TO DETAIL A MUCH EARLIER RETURN TO
WIND CHILL OF -15 F NOT LONG AFTER SUNSET THIS EVENING AND THEN
PERSISTING THROUGH TONIGHT TO NEAR -20 F WELL INTO TUESDAY MORNING.
CLOUDS FROM LAKE MICHIGAN HELD MAINLY WEST OF SE MI DURING THE NIGHT
ARE NOW GAINING EASTWARD GROUND FROM THE OHIO BORDER TO I-96, A
TREND THAT WILL CONTINUE WITH NORTHWARD EXTENT TOWARD I-69 DURING
THE MORNING AS SURFACE TO CLOUD LAYER WIND BACKS MORE WESTERLY. THE
BACKING WIND TREND IS A RESPONSE TO THE LARGER SCALE SURFACE
PRESSURE REFLECTING THE MID LEVEL WAVE INBOUND FROM THE NORTHERN
PLAINS AND MIDWEST. THIS SYSTEM BEGINS TO SHAPE MORNING LAKE EFFECT
FLURRIES AND SCATTERED SNOW SHOWERS INTO GREATER ORGANIZATION THIS
AFTERNOON AND TONIGHT. UNIFORM WESTERLY FLOW USUALLY PRODUCES A
CONVERGENT TROUGH OFF THE SOUTH END OF LAKE MICHIGAN WHICH IS WEAKER
DURING THE DAY IN A WELL MIXED BOUNDARY LAYER. THE MID LEVEL WAVE
WILL SHARPEN UP THE SURFACE TROUGH ON LARGER SPATIAL SCALE TO
STRENGTHEN THE CONVERGENT LAKE EFFECT BANDING WHILE ALSO GIVING A
SUBSTANTIAL BOOST TO CONVECTIVE DEPTH. THE LIMITING FACTOR REMAINS
MOISTURE QUALITY AND MICROPHYSICS AS 850-500 MB MEAN RH BARELY
REACHES 50% WHILE MODEL SOUNDINGS SHOW A SURFACE BASED DGZ THAT
TOGETHER POINT TO A SUB 10:1 SLR. FOR ANY OTHER MOISTURE/THERMAL
PROFILE THE LARGER SCALE MID LEVEL WAVE, SURFACE TROUGH, AND LAKE
INSTABILITY COMBINE FOR AN OUTSTANDING SETUP CAPABLE OF FOCUSING
MULTIPLE BANDS INTO SE MI BETWEEN I-69 AND I-96/696 THIS AFTERNOON
AND TONIGHT. BOTH THE GREATER COVERAGE AND LOWER ACCUMULATION
POTENTIAL ARE IN THE GOING FORECAST AND WILL BE MAINTAINED WITH THIS
UPDATE AS A FEW LOCATIONS ARE ABLE TO GRIND OUT AROUND AN INCH OF
ACCUMULATION BEFORE DIMINISHING TOWARD SUNRISE TUESDAY.
NOT TO BE FORGOTTEN IS THE COLD WEATHER ADVISORY STILL IN EFFECT AS
WIND CHILL IS EXPECTED TO BE IN THE -15 TO -20 F RANGE TUESDAY
MORNING. PASSAGE OF THE MID LEVEL WAVE TONIGHT PULLS THE CENTER OF
ARCTIC HIGH PRESSURE INTO THE CENTRAL PLAINS AND MID MS VALLEY TO
REINFORCE THE CORE OF ARCTIC AIR ACROSS THE GREAT LAKES THROUGH
TUESDAY AND TUESDAY NIGHT. GUIDANCE AIR TEMPERATURES ONLY RISE TO
SINGLE DIGITS ABOVE ZERO WHICH ONLY ALLOWS A SLOW RECOVERY OF WIND
CHILL ABOVE -15 F BY AFTERNOON. ANOTHER RUN TOWARD -20 F IS THEN
LIKELY TUESDAY NIGHT WHILE SURFACE WIND TURNS MORE SOUTHERLY WHICH
GRADUALLY DISPLACES ARCTIC AIR AHEAD OF THE NEXT PLAINS LOW PRESSURE
SYSTEM. THE SURFACE LOW IS PROJECTED TO TRACK THROUGH THE NORTHERN
GREAT LAKES WHILE BRINGING A MODEST PACIFIC MOISTURE SUPPLY INTO A
TEXTBOOK ISENTROPIC LIFT SCENARIO ACROSS LOWER MI DURING THE DAY
WEDNESDAY. SPECIFIC HUMIDITY IN THE 1-2 G/KG RANGE SUPPLIES STRONG
THETA-E ADVECTION ON A 40 KT SW 850 MB JET THAT MAY END UP WORTHY OF
MORE THAN CHANCE POPS WITH SOME LIGHT SNOW ACCUMULATION POSSIBLE
AROUND THE WEDNESDAY NIGHT TIME PERIOD.
THE WEDNESDAY LOW PRESSURE SYSTEM PULLS A COLD FRONT THROUGH THE
GREAT LAKES FOR THURSDAY, HOWEVER THERE IS A GOOD CONSENSUS IN THE
EXTENDED RANGE MODELS THAT INDICATE A WEAKER SURGE OF COLD AIR POST
FRONT FOR THE LATE WEEK PERIOD. MID LEVEL/500 MB HEIGHT STAYS ABOVE
530 DM AND 1000-850 MB THICKNESS ABOVE 1200 METERS COMPARED TO THE
ONGOING ARCTIC OUTBREAK. GUIDANCE TEMPERATURES RETURNING TO THE MID
AN UPPER 20S DURING THE DAY AND TEENS AT NIGHT THEN APPEAR REASONABLE
BUT STILL BELOW NORMAL HEADING INTO THE WEEKEND.
MARINE...
AN ADDITIONAL SURGE OF ARCTIC AIR WILL ARRIVE TODAY, CAUSING WINDS
TO SHIFT OUT OF THE WEST TO WEST-SOUTHWEST AND INCREASE TO THE 15 TO
25 KNOT RANGE. 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 THROUGH THE DAY. THE HEAVY FREEZING SPRAY WARNING REMAINS IN
EFFECT FROM THIS AFTERNOON THROUGH TUESDAY MORNING. A 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 THE COLDEST AIR
HOLDS IN PLACE. 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.
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 FROM 4 PM THIS AFTERNOON TO 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.
AVIATION.....SC
DISCUSSION...BT
MARINE.......TF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page