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000
FXUS63 KDTX 291447
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
947 AM EST FRI NOV 29 2013

.UPDATE...

THE MORNING FOG HAS LIFTED TO A LOW STRATUS DECK OVER LOCATIONS
ROUGHLY ALONG AND NORTH OF A HOWELL TO SANDUSKY LINE. THE 12Z DTX
SOUNDING HAD TWO INVERSIONS BASED BELOW 925MB. WARM AIR ADVECTION
ABOVE 900MB TODAY WILL SUSTAIN A LOW LEVEL INVERSION. THIS ALONG
WITH THE LOW SUN ANGLE THIS TIME OF YEAR WILL MEAN THIS STRATUS
DECK IS GOING TO TAKE WELL INTO THE AFTERNOON TO MIX OUT...IF IT
COMPLETELY MIXES OUT AT ALL. SATELLITE DATA ALSO SUGGESTS THE
SHALLOW COLD LAYER IS MAINTAINING A HEALTHY RESPONSE OFF LAKE
MI...SUPPORTING A GOOD DEAL OF LAKE CLOUDS. THE LIGHT WESTERLY
FLOW MAY ALLOW SOME OF THESE CLOUDS TO FILTER INTO FAR WESTERN
PORTIONS OF SE MI THIS AFTERNOON BEFORE THE LOW LEVEL FLOW BACKS
TOWARD THE SOUTH. THE EXTENT OF LOW CLOUDS WILL SUPPORT LOWERING
FORECAST HIGHS TEMPS A BIT ACROSS THE TRI CITIES/FLINT AND THUMB
REGION.

MEANWHILE...THE WEAK FLOW LOOKS TO BE PREVENTING THE STRATUS FROM
PUSHING SE OF THE IRISH HILLS. THUS MUCH OF METRO DETROIT AND
POINTS SOUTH HAVE SEEN FULL MORNING SUN. IN ANTICIPATION OF MORE
SUN IN THESE LOCALS...AFTERNOON HIGHS IN THE LOW 30S SEEM
REASONABLE.

&&

.AVIATION...ISSUED 550 AM EST FRI NOV 29 2013

//DISCUSSION...

AREAS OF LAKE ENHANCED CLOUDS AND FOG WILL DISSIPATE DURING THE
MORNING AS HIGH PRESSURE PROGRESSIVELY BUILDS INTO THE REGION. VFR
CONDITIONS ARE THEN EXPECTED UNTIL AFTERNOON WHEN DIURNAL MIXING
WILL ALLOW A BORDERLINE LOW VFR/HIGH MVFR STRATOCU CLOUD LAYER TO
DEVELOP. PLAN TO ABSTAIN FROM SPECIFIC MENTION OF MVFR IN THE 12Z
TAF DUE TO LOW CONFIDENCE...OPTING INSTEAD TO MAKE LATER REFINEMENTS
BASED ON OBSERVATIONAL TRENDS. BY TONIGHT, LIGHT SOUTHEAST WINDS
AROUND THE DEPARTING SURFACE HIGH MAY PICK UP SUFFICIENT MOISTURE
FROM LAKE ERIE TO RESULT IN FURTHER DETERIORATION OF CEILINGS
BETWEEN 00Z-09Z, PARTICULARLY FURTHER EAST AT KDET, BUT LIKEWISE LOW
CONFIDENCE PRECLUDES BEING TOO AGGRESSIVE ATTM.

//DTW THRESHOLD THREATS...

* MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FEET

&&

.PREV DISCUSSION...ISSUED 353 AM EST FRI NOV 29 2013

SHORT TERM...TODAY AND TONIGHT

SHORTWAVE RIDGING WILL TRANSLATE THROUGH THE GREAT LAKES REGION
DURING THE NEXT 24 HOURS AGAINST A BACKDROP OF REBOUNDING HEIGHTS
COURTESY OF THE DEPARTING UPPER TROUGH. SUBSIDENCE WILL LIMIT
DIURNAL MIXING DEPTHS TO AROUND 925MB THIS AFTERNOON WITH HEATING
EVEN FURTHER LIMITED BY THE ADVECTION OF HIGH CLOUDS FROM CENTRAL
CANADA WITHIN NW FLOW ALOFT, ESPECIALLY FOR WESTERN AREAS.
THEREFORE, ONLY A LIMITED TEMPERATURE RECOVERY FROM YESTERDAY`S
HIGHS IN THE MID TO UPPER 20S IS FORECAST WITH ONLY THOSE LOCATIONS
IN THE METRO AREA AND POINTS SOUTH EXPECTED TO BREAK 30 DEGREES.
WEAK GRADIENT CONDITIONS IMMEDIATELY BEHIND THE DEPARTING SURFACE
HIGH ARE THEN EXPECTED FOR THE FIRST HALF OF TONIGHT BEFORE EMERGING
RETURN FLOW AND A CONTINUING THICKENING OF MID/HIGH CLOUDS LIMIT THE
RATE OF COOLING FOR THE REST OF THE NIGHT. TWEAKED LOWS UPWARD INTO THE
20-25F RANGE.

LONG TERM...SATURDAY THROUGH THURSDAY

TEMPERATURES WILL GRADUALLY MODERATE THIS WEEKEND INTO EARLY NEXT
WEEK AS THE CORE OF THE CURRENT POLAR HIGH PRESSURE SYSTEM SHIFTS
EAST. TEMPERATURES WILL REMAIN COOL...HOWEVER...AS UPPER TROUGHING
REMAINS IN PLACE. EXPECT HIGHS IN THE MIDDLE 30S TO AROUND 40 INTO
TUESDAY OR SO WITH LOW TEMPERATURES GENERALLY RANGING IN THE 20S.
ANY PRECIPITATION WILL BE VERY LIGHT AND SPOTTY AS SEVERAL WAVES
TRAVERSE THE AREA.

UPPER LEVEL PATTERN DOES BEGIN TO CHANGE BY MIDWEEK AS LARGE UPPER
TROUGH COVERING MUCH OF THE WESTERN HALF OF THE CONUS EVOLVES AND
UPPER RIDGING BUILDS INTO THE GREAT LAKES TO THE EAST OF THIS
FEATURE. THIS WILL BRING MILDER TEMPERATURES YET AND EVENTUALLY
HIGHER PRECIPITATION CHANCES BY THE END OF THIS FORECAST PERIOD.
SO FAR...MODELS HAVE NOT BEEN VERY CONSISTENT WITH THE EVOLUTION OF
THIS TROUGH...OR ANY SHORTWAVES EJECTING FROM IT FOR THAT MATTER.
SO...FORECAST CONFIDENCE REMAINS MORE IFFY THAN USUAL.

MARINE...

A LARGE AREA OF HIGH PRESSURE WILL BUILD INTO THE AREA TODAY AND
THEN CONTINUE EASTWARD OVER THE WEEKEND. SOUTH TO SOUTHWEST WINDS
WILL INCREASE WITHIN PRESSURE GRADIENT BETWEEN THIS DEPARTING HIGH
AND THE NEXT APPROACHING COLD FRONT. WITH MARGINAL TO MODEST
INSTABILITY STILL IN PLACE OVER LAKE HURON...WINDS WILL ONCE AGAIN
BECOME RATHER GUSTY. AT THIS TIME...IT APPEARS THAT WIND GUSTS WILL
GENERALLY TOP OUT AROUND 30 KNOTS ON SATURDAY...BUT A FEW GUSTS MAY
APPROACH GALE FORCE OVER CENTRAL LAKE HURON. THE PASSAGE OF THE WEAK
COLD FRONT SATURDAY NIGHT WILL LEAD TO LIGHTER NORTHWEST WINDS FOR
SUNDAY.

&&

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

LAKE HURON...
     GALE WATCH...LHZ362-LHZ363-LHZ462...FROM 9 AM SATURDAY TO 10 PM
     SATURDAY.

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

&&

$$

UPDATE.......SC
AVIATION.....JVC
SHORT TERM...JVC
LONG TERM....DG
MARINE.......DG


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