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000
FXUS63 KDTX 061656
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1156 AM EST FRI DEC 6 2013


.AVIATION...

//DISCUSSION...

AN MVFR STRATUS DECK HAS BEEN ON THE DOORSTEP OF MBS FOR THE LAST
HOUR. THE COMBINATION OF THE LOW LEVEL MOISTURE FLUX OFF LAKE
MICHIGAN AND THE DEPTH OF THE LOW LEVEL INVERSION SHOULD SUSTAIN
SOME DEGREE OF LOW CLOUDS INTO AT LEAST MBS THIS AFTERNOON AND
EVENING. THE MAIN LIMITING FACTOR WILL BE THE VERY DRY ARCTIC AIR
NOW ENVELOPING THE REGION. THE INCREASING RESPONSE NOTED OFF LAKE
MICHIGAN MAY ALLOW SOME OF THE STRATO CU TO PERIODICALLY ADVANCE
ACROSS FNT AND PTK THIS EVENING.

FOR DTW...THERE IS GROWING CONFIDENCE THAT POOR MOISTURE QUALITY
WILL KEEP ANY LIGHT SNOW/FLURRIES WELL SOUTH OF METRO THIS EVENING.
ALTHOUGH STRATO CU FROM THE WEST SIDE OF THE STATE WILL ATTEMPT TO
PUSH TOWARD THE EAST...THE DEGREE OF LOW LEVEL DRY AIR AND SLIGHT
DOWNSLOPE COMPONENT INTO METRO UNDER A WNW FLOW SUPPORTS NOTHING
MORE THAN SCT MVFR CLOUD BASES THIS EVENING.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE ON CEILINGS BELOW 5000 FT THIS EVENING AND
OVERNIGHT.

&&

.PREV DISCUSSION...ISSUED 1008 AM EST FRI DEC 6 2013

UPDATE...

THE THICK CANOPY OF MID/HIGH CLOUDS AND WEAK LOW LEVEL COLD AIR
ADVECTION THROUGH THE AFTERNOON WILL INHIBIT MUCH IF ANY DIURNAL
RESPONSE. THIS WILL SUPPORT A MINOR DOWNWARD ADJUSTMENT TO TEMPS
THIS AFTERNOON. THE DEPTH OF THE COLD AIR HAS BEEN INCREASING OVER
THE WESTERN GREAT LAKES WHICH IS LEADING TO A BETTER RESPONSE OFF
LAKE MI. THE 12Z DTX SOUNDING SHOWED A DEEP INVERSION BASED NEAR
920MB. THIS SHOULD ALLOW A GOOD DUCT FOR THE WESTWARD EXPANSION OF
LAKE STRATO CU. RAP SOUNDINGS ON BUFKIT SUGGEST SUPERSATURATION
WITH RESPECT TO ICE NEAR THE INVERSION LEVEL. SO IT SHOULD NOT BE
DIFFICULT TO GENERATE SOME FLURRIES FROM THESE LOWER BASED CLOUDS.
THIS WILL BE MORE PROBABLE ACROSS THE SAGINAW VALLEY AND THUMB
GIVEN THE WESTERLY FLOW. FARTHER SOUTH...THE LOW LEVEL FLOW
BECOMES HIGHLY DIVERGENT WHICH MAY KEEP THE LOW CLOUDS CONFINED TO
WRN LOWER MI THROUGH THE AFTERNOON.

PREV DISCUSSION...ISSUED 356 AM EST FRI DEC 6 2013

SHORT TERM...TODAY AND TONIGHT

THE WEATHER FOR SOUTHEASTERN MICHIGAN WILL BE INFLUENCED BY A
BAROCLINIC ZONE THAT IS IN PLACE FROM THE EASTERN GREAT LAKES
THROUGH MUCH OF THE OHIO RIVER VALLEY. THE FRONTAL BOUNDARY WILL
BECOME QUASI-STATIONARY TODAY AS THE VERY STRONG...POLAR JET AXIS
OVERHEAD BECOMES FAIRLY STATIC. CHARACTERISTICS OF THE FRONT OFFERED
BY CROSS SECTIONS ARE: 1. GRADUALLY SLOPED 2. A DOUBLE GRADIENT
STRUCTURE AT ROUGHLY 750 MB AND 550 MB.

A WAVE IS EXPECTED TO RIPPLE ALONG THE BAROCLINIC ZONE LATE THIS
AFTERNOON AS A LOWER TROPOSPHERIC REFLECTION OF RIGHT ENTRANCE
REGION DYNAMICS. OVERALL PRECIPITATION CHANCES WILL BE NEAR ZERO FOR
MUCH OF THE CWA WITH CHANCES VERY LOW ACROSS MONROE COUNTY. THE
REASON IS ANALYSES OF LOW TO MID TROPOSPHERIC -DIV AND DEFORMATION
ADVERTISE VERY LITTLE FORCING. IN ADDITION...CROSS SECTIONS SUPPORT
SUBSIDENCE THIS AFTERNOON BETWEEN THE 750 MB AND 550 MB GRADIENTS
ALONG WITH RELATIVELY HIGH STATIC STABILITY THROUGH A GOOD CHUNK OF
THE COLUMN. A DRY LAYER BELOW THE 750MB GRADIENT WILL PROVIDE AN
EVAPORATION BUFFER. IN THE SPIRIT OF CONTINUITY...CONTINUED TO
INCLUDE A LOW CHANCE POP OF LIGHT SNOW FOR MONROE COUNTY BETWEEN
21-02Z BUT ANY SNOWFALL...IF ANY...WILL BE NEGLIGIBLE. SOME FORCING
VERY HIGH IN COLUMN IS STILL EXPECTED TO OVERLAP SOUTHEASTERN
MICHIGAN WHICH SHOULD PROVIDE AN ABUNDANCE OF HIGH CLOUD FOR MUCH OF
THE DAYLIGHT HOURS.

SLUGGISH MOVEMENT OF THE FRONT TODAY WILL GIVE SOME POTENTIAL AT
AFTERNOON HIGHS DESPITE THE CLOUDS. FREEZING MARK SOUTH...TO MIDDLE
20S NORTH. WIND CHILLS WILL DROP INTO THE TEENS THIS MORNING...THEN
STRUGGLE TO CLIMB ABOVE 20 FOR THE AFTERNOON. SUBSIDENCE OCCURRING
BEHIND THE WAVE LATE TONIGHT ALONG WITH DRY AIR SHOULD ALLOW CLOUDS
TO SCATTER AN HOUR OR TWO BEFORE SUNRISE. TEMPERATURES WILL HAVE THE
POTENTIAL TO DROP...LOWS IN THE TEENS WIND CHILLS IN THE SINGLE
DIGITS FOR ALL OF SOUTHEASTERN MICHIGAN.

LONG TERM...SATURDAY THROUGH THURSDAY

HIGH AMPLITUDE MID LEVEL FLOW ANCHORED BY A SPRAWLING LONGWAVE
TROUGH WILL REMAIN THE CONTROLLING LARGE SCALE FEATURE WELL INTO
NEXT WEEK.  THE WEEKEND BEGINS WITH SE MICHIGAN INITIALLY RESIDING
ALONG THE EASTERN EXTENSION OF THE MAIN HEIGHT FALL CENTER AND WELL
WITHIN THE COLD DOME PERPETUATED BY AN INBOUND 1040 MB ARCTIC HIGH.
AMBIENT AIRMASS WILL CARRY A DEEP DRY LAYER ABOVE 900 MB...WHILE A
CHECK OF UPSTREAM SOUNDINGS ACROSS LAKE MICHIGAN SHOW A PROFILE ALSO
LACKING IN MOISTURE DEPTH WITH SUPPRESSED INVERSION HEIGHTS.  THIS
WOULD INDICATE THE OPPORTUNITY FOR A LAKE AND/OR DIURNALLY ENHANCED
STRATOCU FIELD WILL BE LIMITED.  SOME LINGERING EARLY STRATUS MAY
EXIST...PARTICULARLY ACROSS THE NORTH WITH THE RESIDUAL MOISTURE
SOURCE FROM TODAY PERHAPS SLOWER TO MIX OUT.  MAIN STORY WILL BE
TEMPERATURES...WITH EVEN A HIGH DEGREE OF INSOLATION STRUGGLING TO
MODERATE A THERMAL PROFILE CARRYING 925 MB TEMPERATURES IN THE -11
TO -12C RANGE.  THIS WILL TRANSLATE INTO HIGHS OF LOWER TO MIDDLE
20S...OR A GOOD 15 DEGREE BELOW EARLY DECEMBER NORMS.  THE EXISTING
SURFACE RIDGING AND DEEP DRY LAYER WILL PROMOTE A GOOD RADIATIONAL
COOLING RESPONSE SATURDAY NIGHT.  A GRADUALLY INCREASING CIRRUS
SHIELD WILL BE THE ONE POSSIBLE DISRUPTION TO REALIZING THE FULL
POTENTIAL.  OVERALL STILL LOOKING AT LOWS IN THE TEENS...A FEW
SINGLE DIGIT READINGS NOT OUT OF THE QUESTION IN THE COLDEST
LOCALES.

CONDITIONS INTO SUNDAY REMAIN DEFINED BY THE PRESENCE OF A COLD/DRY
ENVIRONMENT...LOW LEVEL FLOW FLIPPING TO EASTERLY WITH THE ARCTIC
HIGH SLOWLY EASING EASTWARD.  HIGHS AGAIN IN THE 20S...EFFECTIVELY
CONTAINED BY A MORE CONCERTED INCREASE IN HIGH CLOUD.  FOCUS INTO
SUNDAY EVENING/NIGHT THEN TURNS TO A WELL DEFINED PV ANOMALY WORKING
THROUGH THE TROUGH BASE.  THIS WAVE WILL SHEAR INTO THE PREVAILING
SOUTHWESTERLIES ORIENTED FROM THE CENTRAL PLAINS INTO THE GREAT
LAKES THROUGH THE LATTER HALF OF THE WEEKEND.  THIS PROCESS WILL
PROMPT TWO AREAS OF FOCUS...ONE WITHIN A WING OF EMERGING ISENTROPIC
ASCENT AND MOISTURE TRANSPORT ORIGINATING OUT OF THE WESTERN
GULF...AND A SECOND ACCOMPANYING THE PRIMARY REGION OF FORCED ASCENT
CONTAINED WITHIN THE MAIN HEIGHT FALL CENTER AND ALONG THE
DEVELOPING WEAK SURFACE WAVE AND FRONTAL CIRCULATION EJECTING OUT OF
THE PLAINS.  THE OVERALL UPPER JET POSITIONING WOULD TEND TO DIRECT
THE BULK OF THE GULF ORIGINATING MOISTURE AND ATTENDANT WEAK ASCENT
TO OUR SOUTHEAST.  IT REMAINS PLAUSIBLE FOR SOUTHERN SECTIONS OF
SOUTHEAST MICHIGAN TO RECEIVE A GLANCING SHOT ALONG THE WESTERN EDGE
SUNDAY EVENING.  WEAK SURFACE WAVE THEN LIFTS THROUGH LOWER MICHIGAN
SUNDAY NIGHT...DISPLACED SOUTHEAST OF THE MAIN STRIPE OF DCVA AND
DEFORMATION FORCING SHIFTING FROM THE UPPER MS VALLEY INTO THE U.P.
THIS WILL LEAVE SE MICHIGAN UNDER A BROADER LOOKING PERIOD OF
FORCING...STILL SUFFICIENT TOWARD GENERATING A FEW HUNDREDTHS OF QPF
SUNDAY NIGHT.  A SUB-FREEZING THERMAL PROFILE THROUGHOUT WILL
SUPPORT ALL SNOW...ALTHOUGH THE PROFILE WILL BE WARMING WITH
TIME...EFFECTIVELY REDUCING POTENTIAL SNOWFALL RATIOS.

A GENERAL EASTWARD MIGRATION OF THE MEAN LONGWAVE TROUGH WILL DIRECT
A SERIES SHORTWAVES OF SIBERIAN ORIGIN THROUGH THE GREAT LAKES
DURING THE EARLY AND MID WEEK PERIOD.  THIS WILL RESULT IN AN
EXTENDED STRETCH OF WELL BELOW NORMAL TEMPERATURES AS ARCTIC AIR
TAKES FIRM RESIDENCE THROUGHOUT THE WEEK.

MARINE...

WESTERLY WINDS WILL DIMINISH SLIGHTLY TODAY AND TONIGHT AS THE
PRESSURE GRADIENT EASES BEHIND LOW PRESSURE LIFTING INTO QUEBEC.
THIS WILL RESULT IN A LOWER WAVE CONDITIONS THROUGH THIS TIME.
COLDER AIR MOVING ACROSS THE WATERS WILL MAINTAIN WIND SPEEDS IN
THE 15 TO 20 KNOT RANGE ACROSS NORTHERN PORTIONS OF LAKE HURON.
SLIGHT INCREASE IN WINDS EARLY SATURDAY WILL BRING GUSTS JUST SHY
OF GALES ACROSS NORTHERN LAKE HURON.  STRONG HIGH PRESSURE WILL
THEN TAKE CONTROL SATURDAY NIGHT AND SUNDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....SC
UPDATE.......SC
SHORT TERM...CB
LONG TERM....MR
MARINE.......MR


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