Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDTX 122341
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
641 PM EST FRI FEB 12 2016

.AVIATION...

POCKETS OF SNOW SHOWERS EMBEDDED WITHIN A GUSTY POST-FRONTAL
NORTHWEST WIND WILL PERSIST THROUGH THE LATE EVENING HOURS.  RECENT
OBSERVATIONS CONTINUE TO SUGGEST HEAVIER SNOW SHOWERS WILL CARRY
RAPID BUT BRIEF REDUCTION OF VISIBILITY /2-3 SM/.  NORTHWEST GUSTS
OF 20 TO 25 KNOTS WILL BE COMMON DURING THIS TIME...BEFORE EASING
DURING THE EARLY MORNING PERIOD.  CONSIDERABLE REDUCTION IN SNOW
SHOWER COVERAGE EXPECTED AFTER 03Z...ANY ENSUING ACTIVITY OVERNIGHT
DRIVEN BY DOWNSTREAM PENETRATION OF LAKE MOISTURE FROM LAKE
SUPERIOR/MICHIGAN.  THIS WILL PRESENT A LOWER PROBABILITY FOR SNOW
SHOWERS TO REACH MBS/FNT DURING THE EARLY MORNING PERIOD. OTHERWISE
VFR CONDITIONS WITH SOME REDUCTION IN STRATUS EXPECTED AS DRY
ARCTIC AIR TAKES A FIRM HOLD.

FOR DTW...GUSTY NORTHWEST WINDS TO 25 KNOTS AT 310-320 DEG HOLDS
THROUGH LATE EVENING...FREQUENCY AND MAGNITUDE OF GUSTINESS THEN
EASING BEYOND 06Z.  2-3 HOUR WINDOW YET /THROUGH 03Z/ FOR ONGOING
SNOW SHOWERS TO BRING IFR VISIBILITY REDUCTIONS.  LOWER CONFIDENCE
ON CLOUD TRENDS BEYOND 06Z...SOME POTENTIAL FOR CLOUD COVERAGE TO
DIMINISH /EVEN CLEAR/ AS INBOUND DRIER AIR STRENGTHENS.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CEILING AOB 5KFT THROUGH 06Z...THEN LOW SATURDAY
  MORNING.

* LOW TO REACH CROSSWIND THRESHOLDS FROM 300-310 DEGREES PRIOR TO
  04Z.

&&

.PREV DISCUSSION...ISSUED 402 PM EST FRI FEB 12 2016

DISCUSSION...

THE ARCTIC INTRUSION NOW INFILTRATING THE GREAT LAKES REGION WILL
CONTINUE TO BRING A BRIEF PERIOD OF HIGH IMPACT WINTER WEATHER TO
SOUTHEASTERN MICHIGAN LATE THIS AFTERNOON AND EVENING. THE UPDATE
AND AVIATION DISCUSSIONS ISSUED EARLIER PROVIDES A GOOD RUNDOWN OF
WHAT IS EXPECTED DURING THE NEXT 9 HOURS OR SO. A SUMMARY OF
HEADLINES ARE: A WIND ADVISORY IN EFFECT FOR HURON COUNTY WITH 45 TO
50 MPH WINDS POSSIBLE ALONG THE LAKE HURON SHORELINE...AND WINDCHILL
ADVISORY IN THE THUMB FOR WINDCHILLS OF 15 TO 20 DEGREES BELOW ZERO.

AN IMPRESSIVE BAND OF MODERATE TO HEAVY SNOW...ASSOCIATED WITH
ORGANIZED SOUTHWESTERLY FLOW AND CONFLUENCE...HAS EXITED PORTIONS OF
FAR SOUTHEASTERN MICHIGAN OVER THE PAST HOUR. THIS TIMING IS IN
GREAT AGREEMENT WITH MUCH OF THE HI-RESOLUTION GUIDANCE. THE
ORGANIZATION OF THE CONVECTION IN THE WAKE OF THE SW/NE BAND HAS
EVOLVED TO BE MUCH MORE CELLULAR. THE EXPECTATION OVERALL IS THAT
WHILE VISIBILITY OBSTRUCTIONS WILL IMPROVE AND SNOWFALL RATES WILL
DECREASE TEMPORARILY...MODELS CONTINUE TO SUGGEST THAT CONVECTIVE
DEPTHS WILL INCREASE YET ANOTHER 3000 FT OR SO DURING THE NEXT 2-3
HOURS. AS A RESULT...AN INCREASE IN SNOWFALL RATES WITHIN THIS
CELLULAR CONVECTION WILL BE POSSIBLE THROUGH THE EVENING RUSH HOUR.
THE ACTIVITY SHOULD REMAIN ISOLATED IN COVERAGE AND BRIEF IN
DURATION. THE EARLIER UPDATE WENT AGGRESSIVE WITH POTENTIAL SNOWFALL
AMOUNTS THIS AFTERNOON...AND REMAINS A GOOD CALL. THE BEST POTENTIAL
FOR HIGHER IMPACT SNOWFALL RATES WILL LIKELY BE IN THE SAGINAW BAY
REGION AND NORTHER THUMB...AS THE MESOVORTEX NOW DESCENDING
SOUTHWARD OVER NORTHERN LAKE MICHIGAN SHOULD SWING EASTWARD WITH
TIME. THIS MESOSCALE FEATURE SHOULD FAVOR THE SOUTHERN LAKE HURON
BASIN AND TRAILING TAIL OF CONVERGENCE AND SURFACE TROUGH AXIS LYING
OFF OF SURFACE LOW SQUEEZING EASTWARD NORTH OF LAKE ONTARIO.

LATER TONIGHT...SURFACE HIGH PRESSURE WILL EXPAND ACROSS LOWER
MICHIGAN ON THE BACKS OF VERY STRONG LOW LEVEL COLD AIR ADVECTION.
MODELS SHOW THE LAKE AGGREGATE TROUGHING STRIPPING AWAY. NORTH
NORTHWESTERLY GRADIENT FLOW WILL REMAIN OVER THE LOWER PENINSULA
WHICH SHOULD BRING A LAKE SUPERIOR/LAKE MICHIGAN PLUME DOWN INTO
CENTRAL PORTIONS OF LOWER MICHIGAN. SUSPECT THE NAM IS A LITTLE OVER
RESOLVED WITH THE CONVERGENCE BAND...BUT THERE IS ENOUGH SIGNAL
THAT SUGGESTS LAKE EFFECT SNOW WILL BE ABLE TO EXTEND DOWN INTO
PORTIONS OF FAR NORTHERN MIDLAND AND BAY COUNTIES. SNOWFALL
ACCUMULATIONS FOR NORTHERN PARTS OF THE COUNTY SHOULD REMAIN LESS
THAN AN INCH THROUGH SATURDAY MORNING. IT IS THE CLOUDS AND
SLIGHTLY HIGHER THERMAL HEAT WITHIN THE PLUME THAT WILL BE THE
DELINEATOR AND GRADIENT TO THE BITTERLY COLD WINDCHILLS. THE AREAS
EXTENT AND LANGUAGE WITHIN THE WINDCHILL ADVISORY ISSUED EARLIER
REMAINS GOOD. LOOKING FOR WINDCHILLS OF 15 TO 20 DEGREES BELOW
ZERO IN THE THUMB.

THE HEART OF THE SURFACE ANTICYCLONE WILL THEN BUILD OVER SOUTHERN
LOWER MICHIGAN ON SATURDAY AND SATURDAY NIGHT. DRY AIR IN THE COLUMN
AND TOTAL LOSS OF FORCING WILL BRING DRY CONDITIONS TO MUCH OF THE
AREA. WILL LIKELY SEE SOME LAKE EFFECT ACTIVITY SUSTAIN ITSELF IN
THE WARMER THERMAL BUBBLE OUT OVER THE SOUTHERN LAKE HURON
BASIN...BUT CONFIDENCE IS FAIRLY HIGH WITH A DEEPER NORTHWESTERLY
FLOW COMPONENT TO KEEP THE ACTIVITY OUT OF SOUTHEASTERN MICHIGAN.
WHAT IS A DIFFICULT FORECAST IS THE LOW TEMPERATURE FORECAST FOR
SUNDAY MORNING. RAW OUTPUT OF MODEL SEEMS TO BE RUNNING TOO HIGH
WHICH HAS OBLITERATED CONFIDENCE. DEFERRED THIS ISSUANCE AND TOED
THE LINE WITH LOWS IN THE 0 TO -5 DEGREE RANGE. IF CONDITIONS
SETUP...COULD EASILY SEE TEMPERATURES DROP INTO THE TEENS BELOW
ZERO. IT IS OF HIGHER CONFIDENCE THAT A WINDCHILL ADVISORY WILL
LIKELY NOT BE NEEDED FOR SUNDAY MORNING DUE TO A LACK OF WIND.

THE AIRMASS WILL THEN MODERATE RAPIDLY ON SUNDAY WITH SOUTHWESTERLY
RETURN FLOW FORECASTED TO DEVELOP LATE SUNDAY NIGHT AND MONDAY.
MODELS CONTINUE TO SUGGEST A WIDESPREAD LIGHT ACCUMULATION WITH
THIS CLIPPER ENERGY...WITH TIMING PRIMARILY AFTER MIDNIGHT
SUNDAY...IN TIME FOR THE MONDAY MORNING COMMUTE.

A SHORTWAVE TROUGH WILL PIVOT THROUGH THE REGION ON
MONDAY...BRINGING US A CHANCE OF SOME SNOW FOR THE BEGINNING
OF THE WEEK. AT THIS TIME ACCUMULATIONS LOOK TO BE LIGHT
/UNDER AN INCH/. IN ADDITION TO SNOW ON MONDAY...WARM AIR ADVECTION
ACROSS THE GREAT LAKES WILL BEGIN TO MODERATE TEMPERATURES SLIGHTLY.
HIGHS ON MONDAY WILL BE IN THE MID-30S AND OVERNIGHT LOWS WILL DROP
DOWN INTO THE LOW 20S. RIDGE OF HIGH PRESSURE RETURNS FOR
TUESDAY...KEEPING US DRY WITH TEMPERATURES ONCE AGAIN IN THE MID-
30S. BEYOND TUESDAY...MODELS BECOME INCONSISTENT WITH THE TRACK OF A
CLIPPER SYSTEM EARLY WEDNESDAY. ONLY PUT A MENTION OF SNOW IN THE
FORECAST AS THIS SYSTEM COULD VERY EASILY TRACK TO THE SOUTH OF US.
FOR WEDNESDAY NIGHT AND THURSDAY...STRONG SURFACE HIGH PRESSURE
BUILDS OUT OF THE NORTHERN PLAINS...BRINGING MORE DRY WEATHER AND A
RETURN TO SLIGHTLY COOLER TEMPERATURES /UPPER 20S/.

MARINE...

GALE FORCE WINDS THAT HAVE ALREADY DEVELOPED OVER LAKE SUPERIOR AND
NORTHERN LAKE MICHIGAN WILL SPREAD TO LAKE HURON LATE THIS AFTERNOON
AND EVENING AS FRIGID AIR POURS IN BEHIND AN ARCTIC COLD FRONT.
INSTABILITY GENERATED BY COLD AIR GLIDING OVER THE WARMER LAKE WATERS
WILL ALLOW A CORE OF STRONGER WINDS ALOFT TO MIX TO THE LAKE
SURFACE. HIGH-END GALE FORCE GUSTS TO 45 KNOTS ARE EXPECTED BY THIS
EVENING AND WILL LAST INTO THE EARLY OVERNIGHT HOURS. WINDS WILL
SUBSIDE BELOW GALE FORCE SATURDAY MORNING AS HIGH PRESSURE STARTS TO
BUILD INTO THE GREAT LAKES...BECOMING LIGHT OVERNIGHT AS THE HIGH
SETTLES IN OVERHEAD. THE STRONG AND PERSISTENT WINDS WILL ALSO ALLOW
WAVE HEIGHTS TO REACH IN EXCESS OF 10 FEET OVER MUCH OF THE
LAKE...AND COMBINED WITH THE WINDS AND COLD WILL GENERATE AREAS OF
HEAVY FREEZING SPRAY. WHILE WINDS WILL DECREASE TOMORROW...HIGH
WAVES AND FRIGID TEMPERATURES WILL CONTINUE THE THREAT FOR HEAVY
FREEZING SPRAY THROUGH SATURDAY EVENING OVER THE SOUTHERN HALF OF
THE LAKE.

FURTHER SOUTH...SOUTHWEST WINDS WILL TURN WEST AND THEN NORTHWEST
THIS EVENING OVER LAKE ST CLAIR AND WESTERN LAKE ERIE...GUSTING TO
AROUND 30 KNOTS AS THE FRONT SLIDES THROUGH AND COLDER AIR SPILLS
INTO THE AREA.

STRONG INSTABILITY WILL ALSO PROVIDE SNOW SQUALLS OVER ALL OF THE
CENTRAL GREAT LAKES THROUGH TONIGHT...LASTING THROUGH TONIGHT AND
SATURDAY OVER LAKE HURON. THESE WILL BE LOCALLY INTENSE...REDUCING
VISIBILITY TO ONE-QUARTER OF A MILE OR LESS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ049.

     WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 11 AM EST SATURDAY
     FOR MIZ049-054-055-062-063.

LAKE HURON...HEAVY FREEZING SPRAY WARNING UNTIL 10 PM EST SATURDAY FOR LHZ363-
     462>464.

     GALE WARNING UNTIL 10 AM EST SATURDAY FOR LHZ363-421-441>443-
     462>464.

     HEAVY FREEZING SPRAY WARNING UNTIL 10 AM EST SATURDAY FOR LHZ421-
     441>443.

     HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST SATURDAY FOR LHZ361-362.

     GALE WARNING UNTIL 4 AM EST SATURDAY FOR LHZ361-362.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....MR
DISCUSSION...CB/RK
MARINE.......HLO


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.