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000
FXUS63 KDTX 012037
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
337 PM EST SAT MAR 1 2014

.SHORT TERM...TONIGHT

SURFACE COLD FRONT GRADUALLY MIGRATING SOUTHEAST THIS AFTERNOON...
RECENT ANALYSIS PLACING THE BOUNDARY SOUTH OF THE OHIO BORDER.  THIS
PROCESS WITH CONTINUE AS VERY SUBTLE HEIGHT FALLS WORK IN FROM THE
NORTH.  TRAILING MID LEVEL FRONTAL ZONE WILL REMAIN ANCHORED LOCALLY
HEADING INTO TONIGHT, EMBEDDED WITHIN A CONTRACTING QUASI-ZONAL
UPPER HEIGHT FIELD.  THIS MASS ADJUSTMENT SUSTAINING A SOLID UPPER
LEVEL JET CORE AT THE EDGE OF THE THICKNESS GRADIENT, WITH SOME
STRENGTHENING/PHASING OF THE NEXT INBOUND JETLET EXPECTED AS THE
LEFT EXIT REGION PUNCHES INTO LOWER MICHIGAN.  WATER VAPOR ANALYSIS
SHOWS A MINOR 500 MB PERTURBATION LODGED WITHIN THIS FLOW.  THIS
INCREASE IN MID LEVEL DYNAMICS PROMPTING A STEADY EASTWARD EXPANSION
IN SNOWFALL...THE LEAD EDGE NOW AT THE WEST END OF THE LAKE
MICHIGAN SHORELINE.

STEADY DOWNSTREAM PROPAGATION OF THE GOVERNING MID LEVEL FORCING
WILL SUSTAIN THIS BURST OF SNOWFALL INTO SE MICHIGAN WITHIN THE
01Z-03Z WINDOW. CROSS SECTION ANALYSIS SHOWS A PROFILE
CHARACTERIZED BY A PERIOD OF STRONGER BUT RATHER BROAD FGEN IN THE
PRESENCE OF INCREASINGLY FAVORABLE UPPER JET DYNAMICS. 12Z HI RES
GUIDANCE LARGELY PRESENTS A CASE FOR A GOOD BURST OF ACCUMULATING
SNOWFALL ON THE FRONT END EARLY TONIGHT /3-5 HOUR PERIOD CENTERED
02Z-07Z/ AS THE CORE OF MID LEVEL ASCENT INTERSECTS AND ACTIVATES
THE FRONTAL ZONE. THERE MAY BE A TENDENCY BEYOND THIS FOR THE
FORCING TO REALLOCATE QUICKLY TO THE SOUTH IN RESPONSE TO THE
REPOSITIONING OF THE UPPER JET STRUCTURE /OR TRAILING JETLET/,
WITH DRY AIR ADVECTION TAKING A PROGRESSIVE HOLD FROM NORTH TO
SOUTH THROUGH THE EARLY MORNING HOURS AS THE LOW LEVEL FLOW VEERS
TO NORTHERLY ON THE DOWNSTREAM SIDE OF BUILDING CENTRAL PLAINS
HIGH PRESSURE. POTENTIAL FOR A PERIOD OF GOOD DENDRITE PRODUCTION
AND HIGHER SNOWFALL RATES /HALF INCH PER HOUR/ GIVEN THE FORCING
AND PRESENCE OF A DEEP MOIST LAYER RESIDING WITHIN THE -10 TO -13C
THERMAL LAYER. THE OVERALL MOISTURE QUALITY STILL POINTS TO AN
ACHIEVABLE QPF DISTRUBUTION TAPERED FROM .20" SOUTH TO .10" NORTH.
THIS TRANSLATES INTO A SOLID SWATH OF 1 TO 3 INCHES ACROSS THE
AREA TONIGHT, HIGHEST TOTALS M-59 CORRIDOR SOUTHWARD.

WEAK COLD AIR ADVECTION COMMENCES THROUGH THE LATTER HALF OF THE
NIGHT. 925 MB TEMPERATURES WILL ARRIVE IN THE -18 TO -20C RANGE BY
12Z SUNDAY MORNING. THIS WILL ESTABLISH YET ANOTHER WELL BELOW
NORMAL LOW TEMPERATURE DISTRIBUTION. LOWS RANGING FROM LOWER TO
MIDDLE SINGLE DIGITS NORTH TO LOWER TEENS FROM ANN ARBOR TO
DETROIT SOUTHWARD.

&&

.LONG TERM...SUNDAY THROUGH SATURDAY

ANY REMAINING LIGHT SNOW SUNDAY MORNING WILL END AS THE SHORTWAVE
CONTINUES TO THE EAST AND COLD FRONT SINKS FURTHER SOUTHEAST AS NEXT
CENTER OF ARCTIC HIGH PRESSURE BEGINS TO BUILD INTO THE AREA. SNOW
ACCUMULATIONS WILL BE MINIMAL AFTER 12Z SUNDAY WITH LESS THAN AN
INCH EXPECTED. THE NORTHERN EDGE OF THE LIGHT SNOW WILL SHIFT FROM
NEAR THE M 59 CORRIDOR EARLY IN THE MORNING TO THE OHIO STATE LINE
BY NOON WITH LITTLE MORE THAN FLURRIES EXPECTED BY AFTERNOON.

ANOTHER SURGE OF COLD AIR WILL SHIFT INTO THE AREA WITH THE
AFOREMENTIONED HIGH PRESSURE SYSTEM...SO HIGH TEMPERATURES SUNDAY
AND MONDAY WILL RANGE GENERALLY IN THE TEENS WITH LOWS LATE SUNDAY
NIGHT AND MONDAY NIGHT FALLING BELOW ZERO IN MANY LOCATIONS ONCE
AGAIN. SOME CLOUD COVER ASSOCIATED WITH THE NORTHERN FRINGES OF A
WINTER STORM PASSING WELL SOUTH OF THE AREA MAY LIMIT RADIATIONAL
COOLING ENOUGH TO MAINTAIN TEMPERATURES ABOVE ZERO FROM ABOUT
DETROIT ON SOUTH SUNDAY NIGHT. ALSO...A GRADUAL MODERATING TREND
WILL LIMIT THE FALL IN TEMPERATURES AS HIGH PRESSURE SETTLES TO THE
SOUTHEAST OF THE AREA TUESDAY NIGHT. SO...WHILE TEMPERATURES AOB
ZERO WILL BE COMMON FROM LATE EVENING THROUGH AROUND MIDNIGHT OR
SO...TEMPERATURES SHOULD STEADY OUT AND PERHAPS RISE SOMEWHAT
OVERNIGHT AS LIGHT SOUTHEAST WINDS DEVELOP ON THE BACKSIDE OF THE
DEPARTING HIGH PRESSURE.

DEPARTING HIGH PRESSURE WILL BRING ANOTHER SHOT AT SOME VERY COLD
TEMPERATURES WITH HIGHS ONLY IN THE MID TEENS ON TUESDAY. HOWEVER...
A QUICK MOVING CLIPPER SYSTEM BRINGS A CHANCE OF SOME LIGHT SNOW
SHOWERS TO THE REGION ON TUESDAY DURING THE DAY. COULD SEE A QUICK
HALF INCH UP TO AN INCH FOR ALL OF SOUTHEAST MICHIGAN WITH THIS
CLIPPER. THIS SYSTEM IS OUT OF THE AREA BY TUESDAY NIGHT AS HIGH
PRESSURE RETURNS FOR THE REMAINDER OF THE WEEK. DAYTIME TEMPERATURES
WILL SLOWLY INCREASE FROM THE LOW 20S ON THURSDAY INTO THE LOW TO
MID 30S BY NEXT WEEKEND...STILL WELL BELOW NORMAL FOR THE BEGINNING
OF MARCH. ANOTHER SYSTEM LOOKS TO POTENTIALLY IMPACT SOUTHEAST
MICHIGAN NEXT SATURDAY...HOWEVER...MODEL AGREEMENT IS QUITE LOW SO
ONLY PUT A SLIGHT CHANCE OF PRECIP INTO THE FORECAST AT THIS TIME.

&&

.MARINE...

NORTH NORTHWEST WINDS THIS EVENING WILL EASE OVERNIGHT AS PRESSURE
GRADIENT WEAKENS WITH THE THE APPROACH OF HIGH PRESSURE FROM THE
WEST. WINDS WILL REMAIN RELATIVELY LIGHT THROUGH MID WEEK AS THIS
HIGH PRESSURE DRIFTS ACROSS THE REGION THROUGH TUESDAY MORNING AND
ANOTHER HIGH THEN SHIFTS INTO THE GREAT LAKES FROM NORTHERN ONTARIO
BY WEDNESDAY. ONLY A BRIEF SURGE OF SLIGHTLY ELEVATED NORTHEAST FLOW
WILL OCCUR ON TUESDAY NIGHT AS MORE COLD AIR PUSHES SOUTH INTO THE
AREA WITH THIS SECOND HIGH PRESSURE.

&&

.AVIATION...ISSUED 1221 PM EST SAT MAR 1 2014

//DISCUSSION...

COLD FRONT WILL EASE ACROSS SOUTHEAST MICHIGAN THROUGH THE EVENING.
FRONTAL CONVERGENCE MAY BE SUFFICIENT TO GENERATE POCKETS OF LIGHT
SNOW SHOWERS AND INTERMITTENT MVFR CONDITIONS THROUGH THIS TIME.  A
WIDESPREAD AREA OF LIGHT SNOW WILL THEN EXPAND ACROSS ALL TERMINALS
LATE THIS EVENING.  SNOWFALL IS EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY BETWEEN 01Z-03Z, WITH A SOLID PERIOD OF IFR/LOW MVFR IN
ACCUMULATING SNOW THROUGH THE EARLY MORNING HOURS.  SNOW WILL
DIMINISH FROM NORTH TO SOUTH SUNDAY MORNING AS THE MID LEVEL FRONT
SAGS SOUTH AND DRIER AIR WORKS IN ON DEVELOPING NORTHEAST WINDS.
ACCUMULATION FROM 1 TO 3 INCHES, HIGHEST AMOUNTS ACROSS THE PONTIAC/
DETROIT CORRIDOR.

FOR DTW...NARROW CORRIDOR OF MVFR REMAINS TIED TO THE ADVANCING COLD
FRONT.  LOW CONFIDENCE IN DURATION/TIMING OF ANY LOWER CEILING
RESTRICTIONS /MVFR/ THROUGH EARLY EVENING.  DETERIORATING CONDITIONS
AFTER 02Z AS ACCUMULATING SNOWFALL WORKS IN.  TOTAL ACCUMULATION 2
TO 3 INCH RANGE THROUGH SUNDAY MORNING.

//DTW THRESHOLD THREATS...

* MEDIUM CONFIDENCE IN CEILING AT LEAST INTERMITTENTLY FALLING
  BELOW 5000FT THIS AFTERNOON AND EVENING...THEN HIGH CONFIDENCE
  AFTER 02Z.

* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE.

&&

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

&&

$$

SHORT TERM...MR
LONG TERM....DG/RK
MARINE.......DG
AVIATION.....MR

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