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000
FXUS63 KDTX 042316
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
616 PM EST WED DEC 4 2013


.AVIATION...

//DISCUSSION...

CEILINGS AND VISIBILITIES HAVE LIFTED TO MVFR AND VFR RESPECTIVELY
EARLY THIS AFTERNOON. ADDITIONAL MOISTURE IS EXPECTED TO SURGE INTO
THE AREA THIS EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM.
THIS SHOULD BRING ADDITIONAL RAIN SHOWERS...DRIZZLE...AND FOG BACK
INTO THE AREA TONIGHT. THERE IS HIGH CONFIDENCE WITH IFR CONDITIONS
FOR A PERIOD AT ALL SOUTHEAST MICHIGAN TERMINALS TONIGHT...ALTHOUGH
TIMING OF OCCURRENCE IS STILL A LITTLE UNCERTAIN. THE BEST POTENTIAL
WILL BE AFTER 02Z AND BEFORE A COLD FRONT WORKS WEST TO EAST ACROSS
THE AREA BETWEEN 07Z AND 13Z. CONDITIONS WILL IMPROVE BEHIND THE
FRONT ALTHOUGH MUCH COLDER AIR WILL WORK INTO THE REGION AND WEST
WINDS WILL GUST TO 25 KNOTS THURSDAY FROM LATE MORNING THROUGH EARLY
EVENING.

FOR DTW...CONDITIONS WILL DETERIORATE AGAIN DURING THE EVENING AS
ADDITIONAL MOISTURE SURGES UP INTO SOUTHERN LOWER MICHIGAN. THE BEST
TIMING FOR IFR CONDITIONS TO DEVELOP LOOKS TO BE JUST AHEAD OF THE
FRONTAL PASSAGE...STARTING AT AROUND 07Z. WILL HAVE TO MONITOR
POTENTIAL FOR IFR CONDITIONS TO DEVELOP AS EARLY AS 02Z AS UPSTREAM
OBSERVATIONS INDICATE.


//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET THROUGH THURSDAY
  AFTERNOON.

* LOW CONFIDENCE WITH CEILINGS BELOW 200 FEET OR VISIBILITY BELOW
  1/2 MILE TONIGHT.

&&

.PREV DISCUSSION...ISSUED 344 PM EST WED DEC 4 2013

SHORT TERM...THROUGH TONIGHT

LOW PRESSURE WILL DEEPEN AS IT TRACKS FROM IOWA/MINNESOTA TO NORTH
OF LAKE SUPERIOR TONIGHT...AS THE UPPER WAVE DRIVING THE SYSTEM
TAKES ON A NEGATIVE TILT.

WARMER AIR WILL CONTINUE TO SURGE UP INTO LOWER MICHIGAN IN THE WARM
SECTOR AHEAD OF THE SYSTEM TONIGHT. TEMPERATURES WILL REMAIN WELL
INTO THE 40S AND EVEN 50S FOR MOST OF THE NIGHT BEFORE THEY START TO
FALL TOWARDS DAYBREAK AS A STRONG COLD FRONT BEGINS TO PASS THROUGH
THE AREA...STARTING AT AROUND 500 AM.

PRECIPITATION CHANCES REMAIN A LITTLE MORE TRICKY TO FORECAST AS
SEVERAL FEATURES ASSOCIATED WITH THE LOW PRESSURE SYSTEM MOVE ACROSS
THE AREA. THE FIRST WILL BE A SECONDARY WARM FRONT NOW ORIENTATED
NORTHWEST TO SOUTHEAST FROM NORTHERN INDIANA TO SOUTHERN OHIO. THIS
BOUNDARY WILL LIFT UP ACROSS SOUTHEAST MICHIGAN THIS EVENING.
SHOWERS ARE PRETTY SCATTERED ALONG THIS FRONT RIGHT NOW...BUT
ANTICIPATE THEY SHOULD FILL IN A BIT AS THE LOW-LEVEL JET RAMPS UP
(50 KNOTS) AFTER 21Z AND THE RIGHT ENTRANCE REGION OF AN UPPER JET
LIFTING INTO THE UPPER MIDWEST BECOMES POSITIONED OVERHEAD. THERE
SHOULD BE PLENTY OF MOISTURE AROUND FOR THE FORCING TO WORK
WITH...WITH A REALLY GOOD THETA-E SURGE EXPECTED THIS EVENING (PW
VALUES RISING TO ABOUT 1 INCH...HEALTHY FOR DECEMBER).
OVERALL...CHANCES FOR MEASURABLE RAIN LOOK HIGHEST TONIGHT BETWEEN
21Z AND 02Z AS THIS ALL LIFTS THROUGH. BEYOND THAT...EXPECTING MORE
A MORE SHOWERY PATTERN TO TAKE HOLD OVERNIGHT AHEAD OF THE COLD
FRONT. DRY AIR ABOVE 700MB AND SATURATION IN THE LOWEST 100MB SHOULD
EVEN LIMIT MUCH OF THE ACTIVITY TO DRIZZLE. ANTICIPATING A
REDEVELOPMENT OF FOG OVERNIGHT AS WARM AIR AND MOISTURE CONTINUE TO
GLIDE OVER THE COLD GROUND (SOIL TEMPS BELOW FREEZING DOWN TO ABOUT
5 INCHES...AS MEASURED AT DTX THIS AFTERNOON). SOUTH TO SOUTHEAST
WINDS PICKING UP OVER 10 MPH OVERNIGHT SHOULD HELP LIMIT THE THREAT
FOR WIDESPREAD DENSE FOG...BUT THIS IS STILL A POSSIBILITY THAT WILL
HAVE TO BE MONITORED...ESPECIALLY IF WINDS END UP CALMER THAN
EXPECTED.

LONG TERM...

THE SURFACE COLD FRONT IS EXPECTED TO CLEAR SOUTHEAST MICHIGAN
AROUND 12Z THURSDAY...WITH GOOD RIDGING AND COLD ADVECTION FOLLOWING
THROUGH THE DAY...AS 925 MB TEMPS FALL INTO THE MID NEGATIVE SINGLE
NUMBERS BY DAY`S END...AND AROUND 10 BELOW ZERO BY FRIDAY
MORNING...PER 12Z EURO. THIS WILL SUPPORT SLOWLY FALLING
TEMPERATURES DURING THURSDAY.

OUR MASSIVE UPPER LEVEL TROUGH AND ARCTIC AIR HAS NOW MOVED EAST
INTO THE ROCKIES...AND STRONGLY CONFLUENT SOUTHWEST FLOW WILL EXIST
OVER THE GREAT LAKES REGION. HOWEVER...WE ARE STILL LEARY OF MID
LEVEL FGEN RESPONSE AS TWO JET STREAKS/PIECES OF ENERGY ROUND THE
BASE OF THE TROUGH AND EJECT RAPIDLY NORTHEAST...WITH EARLY
THURSDAY  EVENING AND LATE FRIDAY LOOKING TO BE THE BEST ESTIMATE OF
TIMING BASED ON MODEL CONSENSUS OF CANADIAN/EURO/GFS/NAM.
HOWEVER...THERE IS LITTLE IF ANY BUCKLE OF THE FLOW...AS 850-700 MB
MOISTURE/SPECIFIC HUMIDITIES SHOW A STEADY DECREASE THURSDAY THROUGH
FRIDAY....WITH 850 MB MOISTURE MINIMUM IN PLACE OVER SOUTHERN LOWER
MICHIGAN ON FRIDAY...AS DEW PT DEPRESSIONS CHECK IN AT AROUND -35 C
FOR MOST OF SOUTHEAST MICHIGAN. THE EXCEPTION BEING TOWARD THE OHIO
BORDER...WHERE WE WILL CONTINUE TO CARRY CHANCE POPS THURSDAY
NIGHT-FRIDAY JUST IN CASE ONE OF THE UPPER WAVES IS A BIT STRONGER
OR THE BAROCLINIC ZONE IS NOT DISPLACED AS FAR EAST.

SPRAWLING HIGH PRESSURE (1040 MB) WILL BUILD INTO THE WESTERN GREAT
LAKES REGION FOR SATURDAY. ARCTIC ORIGIN OF THE AIRMASS MAKES SKY
FORECAST DIFFICULT WITH THE COLD WESTERLY FLOW (925 MB TEMPS IN THE
MID NEGATIVE TEENS) OFF LAKE MICHIGAN. SUCH COLD AIRMASS COULD
PRODUCE FLURRIES...BUT FORECAST IS SKEWED TOWARD MORE OPTIMISTIC...
MOSTLY SUNNY FORECAST UNTIL WE FULLY RESOLVE WHAT LOOKS TO BE VERY
LOW INVERSION HEIGHT/SHALLOW CLOUD DEPTH.

HIGH PRESSURE BUILDS INTO THE GREAT LAKES ON SATURDAY AND WILL HOLD
THROUGH SUNDAY MORNING BRINGING BELOW NORMAL TEMPERATURES TO
MICHIGAN. BY SUNDAY AFTERNOON...A LOW PRESSURE SYSTEM WILL BE
PUSHING CLOSER TO SE MI WITH THE MODELS SHOWING THE LOW TRACKING
ACROSS THE EASTERN GREAT LAKES SUNDAY NIGHT INTO MONDAY.  MAIN
CONCERN WITH THIS SYSTEM WILL BE PRECIPITATION TYPE AND TIMING AS IT
LOOKS LIKE SE MI WILL BE MAINLY ALL SNOW WITH THE POTENTIAL FOR
SOUTHEASTERN AREAS OF THE CWA SEEING A BRIEF RAIN/SNOW MIX MONDAY
MORNING.  SCATTERED SNOW SHOWERS MAY LINGER BEHIND AS THE LOW TRACKS
OFF TO THE NORTHEAST MONDAY/TUESDAY AND NORTHWESTERLY FLOW SETS UP.
HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA WEDNESDAY AND
THURSDAY...WITH A REINFORCING SHOT OF EVEN COLDER AIR AS HIGHS ARE
ONLY EXPECTED TO REACH AROUND 20 DEGREES.

MARINE...

STRONG EASTERLY WINDS GUSTING AROUND 30 KNOTS THIS AFTERNOON
NORTH OF PRESQUE ISLE AS WARM FRONT LIFTS NORTH INTO THE CENTRAL
GREAT LAKES. THIS WARM FRONT WILL BRING MUCH MILDER AIR TO THE
REGION...LEADING TO MORE STABLE LOW LEVEL PROFILES...WHICH IS
EXPECTED TO CAP THE WINDS OVER LAKE HURON AT AROUND 30 KNOTS. STRONG
LOW OVER LAKE SUPERIOR LATE TONIGHT WILL BE TRACKING NORTHEAST AND
THEN NORTH INTO JAMES BAY DURING THE DAY TOMORROW...WITH COLD FRONT
PASSAGE OCCURRING EARLY IN THE DAY. PLENTY OF COLD AIR STREAMING IN
DURING THURSDAY AND THURSDAY NIGHT WILL PROMOTE DEEPER MIXING...AND
CONFIDENCE IS HIGH MANY LOCATIONS OVER LAKE HURON WILL GUSTS TO 30
KNOTS. ACROSS THE NORTH THIRD OF LAKE HURON WILL UPGRADE THE WATCH
TO A WARNING. THE BIGGEST HANGUP IS WIND DIRECTION WILL BE SLIGHTLY
SOUTH OF DUE WEST DUE TO THE LOW TRACK...AND WOULD PREFER DUE
WESTERLY OR NORTHWEST TO FULLY MAXIMIZING CHANNELING THROUGH THE
STRAIGHTS. EVEN SO...GALE FORCE WINDS SEEM LIKELY THURSDAY INTO
THURSDAY NIGHT AS CANADIAN MODEL IS ALSO SHOWING A SURFACE TROUGH
PASSING THROUGH DURING THE EARLY EVENING HOURS WHICH SHOULD ONLY
HELP INCREASE THE WINDS.

EXPANSIVE HIGH PRESSURE WILL BUILD IN FOR THE FIRST HALF OF THE
WEEKEND...LEADING TO LIGHT WINDS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     GALE WARNING...LHZ361-LHZ362...FROM 7 AM THURSDAY TO 7 AM FRIDAY.

     SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
     FROM PORT AUSTIN TO HARBOR BEACH...UNTIL 5 AM FRIDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT
     HURON...UNTIL 7 PM THURSDAY.

     SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 4 AM THURSDAY TO 10
     PM THURSDAY.

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

&&

$$

AVIATION.....KURIMSKI
SHORT TERM...HLO
LONG TERM....SF/SS
MARINE.......SF


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