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000
FXUS63 KDTX 032349
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
649 PM EST TUE DEC 3 2013

.UPDATE...

SNOW CONTINUES TO CHANGEOVER TO RAIN ACROSS THE SAGINAW VALLEY AND
NORTHERN THUMB THIS EVENING. HOWEVER A LOW LEVEL LAYER OF COLD AIR
CONTINUES TO CAUSE ISSUES AS THE RAIN FALLS INTO A SUB FREEZING
SURFACE COLD LAYER. DESPITE EARLIER SNOWFALL AND TREATED
ROADWAYS...SEVERAL REPORTS FROM COUNTY DISPATCH AND SPOTTERS
INDICATE THAT MANY ROADWAYS HAVE BECOME ICE COVERED...MAINLY ON
UNTREATED ROADWAYS AND OVERPASSES. A MIXED BAG OF
SNOW...SLEET...RAIN AND FREEZING RAIN ARE EXPECTED THIS EVENING
ACROSS THE NORTHERN THUMB AND SAGINAW VALLEY THIS EVENING AHEAD OF
THE WARM FRONT AS UPSTREAM RADAR OBSERVATIONS SHOW PLENTY OF
UPSTREAM PRECIPITATION. DESPITE THE MIXED BAG...FREEZING RAIN IS
EXPECTED TO BE THE MAIN CULPRIT IN SLICK ROADWAYS...THEREFORE WILL
ISSUE A FREEZING RAIN ADVISORY THROUGH THE EVENING HOURS FOR THE
AFOREMENTIONED TROUBLE SPOTS. TEMPERATURES ARE EXPECTED TO SLOWLY
RISE THROUGH THE OVERNIGHT HOURS INTO THE MID 30S AROUND MIDNIGHT.
WITH THIS TIME WINDOW IN MIND WILL ISSUE THE ADVISORY THROUGH
MIDNIGHT.

&&

.AVIATION...ISSUED 630 PM EST TUE DEC 3 2013

//DISCUSSION...

AREAS OF RAIN WILL CONTINUE OVERNIGHT AS A WARM FRONT LIFTS NORTH
THROUGH SOUTHEAST MICHIGAN. AT MBS A MIXED BAG OF PRECIPITATION IS
STILL EXPECTED AS THIS SITE IS EXPECTED TO REMAIN IN THE COLD LAYER
THROUGH THE EVENING HOURS. FREEZING RAIN IS EXPECTED TO BE THE MAIN
THREAT THIS EVENING. CONDITIONS HAVE ALREADY OR WILL SOON
DETEROIRATE TO MVFR WITH POCKETS OF IFR BEHIND THE WARM FRONT. IN
ADDITION FOG IS EXPECTED TO DEVELOP ACROSS THE AREA LOWERING
VISIBILITIES QUITE SIGNIFICANTLY THROUGH EARLY MORNING WEDNESDAY.
RAIN SHOWERS WILL CONTINUE ACROSS THE NORTHERN SITES /MAINLY MBS/
THROUGH MOST OF THE OVERNIGHT HOURS. RAIN SHOWERS WILL RETURN
WEDNESDAY MORNING TO ALL TAF SITES.

FOR DTW...FOG AND LOWERING CIGS WILL MOVE INTO THE AREA OVERNIGHT.
STILL SOME UNCERTAINTY REGARDING HOW DENSE FOG WILL BECOME.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT THROUGH THE TAF PERIOD.

&&

.PREV DISCUSSION...ISSUED 333 PM EST TUE DEC 3 2013

SHORT TERM...TONIGHT

A WARM FRONT WILL CONTINUE TO PUSH NORTHWARD ALLOWING RAIN SHOWERS
TO CONTINUE THROUGH THIS EVENING.  WITH TEMPERATURES STAYING WELL
ABOVE FREEZING...ALL PRECIPITATION WILL BE IN THE FORM OF RAIN. HAVE
KEPT A CHANCE OF RAIN THROUGH THE FIRST HALF OF THE OVERNIGHT HOURS
ESPECIALLY FOR THE NORTHERN WHERE IT WILL TAKE LONGER FOR THE FRONT
TO MAKE IT THROUGH THE AREA. WHILE SOUTH OF I-69 SHOULD BE MOSTLY
CLEAR OF RAIN AFTER MIDNIGHT...THE MAIN CONCERN FOR THIS REGION WILL
BE CHANCE OF FOG DEVELOPMENT AS SIGNIFICANT LOW LEVEL MOISTURE
FILTERS IN BEHIND THE FRONT AND THE GROUND REMAINS MOIST FROM
AFTERNOON RAIN SHOWERS. CONFIDENCE IS STILL A LITTLE UNCERTAIN
REGARDING HOW MUCH FOG WILL DEVELOP AND LOCATION OF GREATEST IMPACT.
THEREFORE...HAVE ONLY INCLUDED PATCHY FOG FOR THE CWA AT THIS TIME.
THIS WILL PROBABLY HAVE TO BE FINE TUNED AS THE EVENING PROGRESSES.
MINIMUM TEMPERATURES WILL BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR
ACROSS THE CWA. EXPECT LOW TEMPS IN THE UPPER 30S ON TOWARDS THE
OHIO BORDER AND LOWS IN THE MID 30S IN THE NORTHERN CWA.

LONG TERM...

UPPER LEVEL TROUGH/ENERGY OVER THE PACIFIC NORTHWEST DROPPING SOUTH
THIS AFTERNOON...WITH ADDITIONAL ENERGY EXTENDING NORTHWEST INTO THE
GULF OF ALASKA. LONGWAVE TROUGH WILL ENCOMPASS THE WESTERN THIRD OF
THE CONUS TOMORROW MORNING...WITH RAPID CYCLOGENESIS TAKING PLACE
OVER THE MIDWEST. THE STRENGTHENING LOW IS THEN EXPECTED TO TRACK
NORTHEAST THROUGH LAKE SUPERIOR WEDNESDAY NIGHT. GOOD SURGE OF
MOISTURE WITH ANOTHER WARM FRONT TOMORROW AFTERNOON/EVENING...AS PW
VALUES SHOWN TO INCREASE AND EXCEED SLIGHTLY EXCEED 1 INCH WITH GOOD
SURGE OF ISENTROPIC ASCENT. THE QUESTION IS AFTER 00Z THURSDAY...AS
AGGRESSIVE DRY SLOT (700 MB RH OF 30 PERCENT) MOVES INTO SOUTHEAST
MICHIGAN (PER GFS/NAM). THERE STILL WILL BE SOME LINGERING LOW LEVEL
MOISTURE/CONVERGENCE ALONG/AHEAD OF THE COLD FRONT WHICH TAKES
MOST/ALL OF THE NIGHT TO WORK THROUGH...ALONG WITH HIGHER DEW PTS
(50+ DEGREES). THE 12Z EURO IS SLOWER WITH MOISTURE AXIS/WARM
FRONT...AND FORECAST WILL BE WEIGHTED HEAVILY IN THIS
DIRECTION...FOCUSING THE RAIN SHOWERS AROUND 00Z MARKER. TEMPS WERE
BUMPED UP WEDNESDAY NIGHT INTO THURSDAY WITH THE SLOWER TIMING.

THE EASTWARD PUSH OF THE BAROCLINIC ZONE/COLD FRONT AND
CORRESPONDING SURFACE RIDGING/DRYING FOR THURSDAY WILL BE
IMPORTANT...AS ONE IF NOT TWO UPPER LEVEL WAVES/JET STREAKS EJECT
FROM TEXAS AND TRACK NORTHEAST THURSDAY NIGHT/FRIDAY TIME FRAME. THE
MAIN UPPER LEVEL PV SOURCE APPEARS TO BE THE SOUTHERN UPPER LEVEL
LOW LOCATED AT 25N 131W IN PACIFIC. THERE IS NO QUESTION IT LOOKS TO
BE A CLOSE CALL FOR ACCUMULATING SNOW TOWARD THE OHIO BORDER...AS
12Z EURO SHOWS 850-700 MB SPECIFIC HUMIDITY JUMPING TO 3 C THURSDAY
NIGHT...WHILE THE 12Z NAM IS LIKING THE FRIDAY UPPER WAVE EVEN
BETTER. UPPER LEVEL FLOW IF HIGHLY CONFLUENT...AND CONFIDENCE IS NOT
HIGH WITH SUCH SHARP LOW LEVEL GRADIENT/BAROCLINIC ZONE.

ARCTIC AIR WILL CONTINUE TO FILTER INTO THE AREA OVER THE
WEEKEND...WITH HIGHS BOTH SATURDAY AND SUNDAY IN THE LOW TO MIDDLE
20S AND LOWS IN THE TEENS...A GOOD 10 TO 15 DEGREES BELOW NORMAL.

MARINE...

DEEPENING LOW PRESSURE WILL LIFT OUT OF THE MIDWEST TOMORROW AND
THROUGH THE WESTERN GREAT LAKES TOMORROW NIGHT. EASTERLY WINDS OUT
AHEAD OF THIS LOW TONIGHT AND WEDNESDAY...WITH GUSTS TO 25 KNOTS
EXPECTED OVER THE NORTH THIRD OF LAKE HURON...AS WARM FRONT LIFTS
NORTH AND FUNNELING OF WINDS OCCURS. A GOOD DEAL OF WARM AIR
SPREADING OVER THE CENTRAL GREAT LAKES WEDNESDAY NIGHT WILL LEAD
TO MORE STABLE LOW LEVEL PROFILES AHEAD OF THE COLD FRONT.
HOWEVER...EXCELLENT LOW LEVEL COLD ADVECTION BEHIND THE FRONT
WILL PROMOTE MUCH BETTER MIXING...AND IT APPEARS AS THE STRONG LOW
MOVES OVER JAMES BAY...THE GRADIENT SHOULD BE SUFFICIENT TO
PRODUCE WESTERLY GALES OVER THE NORTH THIRD/HALF OF LAKE
HURON...AND HAVE GONE AHEAD AND ISSUED A GALE WATCH. COLDER AIR
WILL CONTINUE TO FILTER INTO THE GREAT LAKES REGION ON
FRIDAY...BUT WINDS WILL DECREASE AS GRADIENT LOOSENS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...FREEZING RAIN ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-
     MIZ055...UNTIL MIDNIGHT WEDNESDAY.

LAKE HURON...
     GALE WATCH...LHZ361-LHZ362...FROM 5 AM THURSDAY TO MIDNIGHT FRIDAY.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

UPDATE.......KURIMSKI
AVIATION.....KURIMSKI
SHORT TERM...RK
LONG TERM....SF/DE
MARINE.......SF


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