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000
FXUS63 KDTX 032008
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
308 PM EST MON MAR 3 2014

.SHORT TERM...THROUGH TONIGHT

ABUNDANT EARLY MARCH SUNSHINE HAS DONE ONLY A LITTLE TO WARM
TEMPERATURES THIS AFTERNOON...WITH LOCATIONS ACROSS SOUTHEAST
MICHIGAN ONLY REACHING BETWEEN 9-15 DEGREES SO FAR THIS AFTERNOON.
THIS IS 25 TO 30 DEGREES BELOW NORMAL. RECORDS FOR LOW MAX TEMPS ARE
STILL THREATENED AT MBS (RECORD IS 13) AND FNT (RECORD IS 16) FOR
TODAY. HAVE ALREADY SEEN AN HOURLY TEMP OF 13 AT DTW...SO THE RECORD
SHALL REMAIN AT 12 FOR MARCH 3.

TEMPERATURES WILL COOL RAPIDLY THIS EVENING AS HIGH PRESSURE KEEPS
SKIES CLEAR AND WINDS FAIRLY LIGHT. EXPECT MOST LOCATIONS TO BE
AROUND OR JUST BELOW ZERO BY 10 PM OR SHORTLY AFTER. MINS SHOULD BE
REACHED AFTER MIDNIGHT BEFORE CLOUDS BEGIN TO INCREASE AHEAD OF AN
INCOMING UPPER WAVE AND TEMPS START TO RISE LATE TONIGHT/EARLY
TUESDAY.

HIGH PRESSURE WILL EXIT INTO NEW ENGLAND TONIGHT AS THE WEAK UPPER
WAVE OVER SOUTHERN MANITOBA AND WESTERN ONTARIO SLIDES
EAST...PUSHING A WEAK TROUGH OF LOW PRESSURE INTO LAKE SUPERIOR
LATE. AHEAD OF THIS SYSTEM...WARM AIR ADVECTION WILL COMMENCE IN THE
LOW TO MID LEVELS...WITH THE 850-700MB FRONT BECOMING POSITIONED
OVERHEAD DURING THE OVERNIGHT HOURS. MODELS SHOW BROAD BUT LIGHT
ASCENT OCCURRING ALONG THE 290K ISENTROPIC SURFACE...WHICH SHOULD AT
LEAST AMOUNT TO A FAIR INCREASE IN MID-LEVEL CLOUDS FOR THE AREA
OVERNIGHT. ASCENT AT THE AT THE 290K SURFACE...A LITTLE LOWER...IS
STRONGER BUT WILL FIRST HAVE TO OVERCOME DRY AIR IN PLACE OVER
SOUTHEAST MICHIGAN BEFORE PRECIPITATION STARTS TO REACH THE GROUND.
INCREASING FGEN ALONG THE MID-LEVEL FRONT SHOULD ALSO BEGIN HELPING
LATE. KEPT POPS/SNOW PREDOMINANTLY NORTH OF THE I-69 CORRIDOR BEFORE
SUNRISE...WITH 100 PERCENT POPS UP TOWARDS MIDLAND AND BAY COUNTIES.
THIS COINCIDES WITH STRONGER ASCENT ALONG THE 290K SURFACE.


ONCE WE DO SATURATE...EXPECT A QUICK DROP IN VISIBILITY TO
BELOW ONE MILE AND FAST ACCUMULATIONS GIVEN THE STRONG FORCING. DEEP
ISOTHERMAL LAYER CENTERED RIGHT IN THE MIDDLE OF THE DENDRITIC
GROWTH ZONE SHOULD GENERATE GOOD-SIZED FLAKES...ONLY AIDING
VISIBILITY DROPS AND ACCUMULATIONS.

&&

.LONG TERM...

LARGE SCALE PATTERN DEFINED BY LOWER AMPLITUDE WEST-NORTHWEST FLOW
THROUGH THE MIDWEEK PERIOD.  WEAK MID LEVEL WAVE NOTED ON WATER
VAPOR EJECTING ACROSS THE PACIFIC NORTHWEST WILL QUICKLY TRANSLATE
DOWNSTREAM...REACHING THE GREAT LAKES BY EARLY TUESDAY.  RELATIVELY
MODEST LOW LEVEL RESPONSE DOWNSTREAM OF THE SUBTLE HEIGHT FALLS WILL
YIELD A CORRIDOR OF WARM AIR ADVECTION WITHIN DEVELOPING SOUTHWEST
FLOW.  THE RESULTANT ISENTROPIC ASCENT WILL SHIFT ACROSS SE MICHIGAN
THROUGH THE FIRST HALF OF TUESDAY.  THIS WILL OCCUR IN CONJUNCTION
WITH WEAK FGEN IN THE PRESENCE OF RIGHT ENTRANCE REGION JET
DYNAMICS.  THIS WILL RESULT IN AN INCREASING COVERAGE OF LIGHT SNOW
THROUGH THE MORNING HOURS.  THE PLACEMENT OF SLIGHTLY STRONGER
FORCING AND SOME LONGER RESIDENCE TIME WILL FOCUS THE HIGHER
ACCUMULATION POTENTIAL TOWARD THE NORTH.  DEEP SATURATED COLUMN
ALIGNS SOLIDLY IN THE VICINITY OF THE -15C ISOTHERM, POINTING
FAVORABLY TO SNOW RATIOS ARRIVING ON THE HIGHER END /17-19:1/.  THIS
TRANSLATES INTO ACCUMULATION OF 1 TO 2 INCHES I-69 NORTH BEFORE THE
SNOW TAPERS OFF FROM WEST TO EAST EARLY AFTERNOON. HIGHEST AMOUNTS
WILL FOCUS FROM THE TRI-CITIES INTO THE THUMB.  ACCUMULATION BELOW
AN INCH TOWARD THE SOUTH, WITH A SHARPER DROP OFF IN BOTH MAGNITUDE
AND DURATION OF ASCENT YIELDING SIMPLY A BRIEF PERIOD OF LIGHT SNOW
/IF ANY/ WITH LIMITED ACCUMULATION POTENTIAL ANN ARBOR-DETROIT
CORRIDOR SOUTHWARD.   MORE OF THE SAME IN THE TEMPERATURE
DEPARTMENT, ALTHOUGH DAYTIME READINGS DO RECEIVE A SLIGHT NUDGE
UPWARD FROM THOSE NOTED TODAY GIVEN THE GENERAL ADVECTION. STILL
LOOKING AT HIGHS STRUGGLING TO CLIMB MUCH ABOVE 20 DEGREES.

ELONGATED CORRIDOR OF HEIGHT FALLS FIXATED WITHIN A CONTROLLING
CENTRAL PACIFIC JET WILL LIFT OUT OF THE ROCKIES TUESDAY NIGHT AND
WEDNESDAY.  MAIN HEIGHT FALLS WILL CENTER WELL TO THE SOUTH, WHILE
STRONG CENTRAL CANADIAN HIGH PRESSURE ENSURES COLD NORTHEAST/EAST
FLOW HOLDS FIRM ACROSS THE GREAT LAKES.  THIS CONFIGURATION WILL
PROMPT A SHARPENING OF THE EXISTING MID LEVEL TEMPERATURE GRADIENT
DRAPED ACROSS LOWER MICHIGAN/NORTHERN OHIO VALLEY.  A STRIP OF
HEIGHTENED MID LEVEL FGEN WILL TEND TO ALIGN WITHIN THIS CORRIDOR
ON WEDNESDAY, ALTHOUGH SOME UNCERTAINTY REMAINS IN BOTH THE
PLACEMENT AND MAGNITUDE.  THE UNDERLYING MOISTURE QUALITY WOULD BE
SUFFICIENT TO SUPPORT A BROADENING AREA OF LIGHT SNOW FOR A TIME
EARLY WEDNESDAY AS THE FRONTAL ZONE ACTIVATES, WITH SOME
CONSOLIDATION AND MOVEMENT TO THE SOUTH AS WEAK HEIGHT FALLS NUDGE
IN.  THIS WILL PLACE THE SOUTHERN COUNTIES IN A BETTER POSITION FOR
SOME LIGHT ACCUMULATION /INCH OR LESS/.  GENERAL MODERATION OF
THE THERMAL PROFILE WITH TIME WILL WORK HIGHS BACK INTO THE LOWER
AND MIDDLE 20S BY WEDNESDAY...BUT STILL A GOOD 15 DEGREES BELOW
EARLY MARCH NORMS.

HIGH PRESSURE WILL REMAIN OVER SOUTHEAST MICHIGAN EARLY THURSDAY
BEFORE SLOWLY DEPARTING TO THE EAST. DRY CONDITIONS WILL PREVAIL ON
THURSDAY WITH AN INCREASING CLOUD TREND THROUGHOUT THE DAY BECOMING
MOSTLY CLOUDY BY THURSDAY NIGHT. A WEAK FRONTAL BOUNDARY WILL SLIDE
ACROSS THE REGION ON FRIDAY BRINGING ANOTHER CHANCE AT SNOW TO
SOUTHEAST MICHIGAN. TIMING IS A BIT UNCERTAIN AT THIS TIME FOR THIS
FEATURE WITH THE CURRENT MODEL TRENDS. HOWEVER...RIGHT NOW THE BEST
CHANCE FOR SNOW LOOKS TO BE MAINLY IN THE AFTERNOON/INTO FRIDAY
EVENING. A FEW LINGERING SNOW SHOWERS COULD BE POSSIBLE ON SATURDAY
BEFORE STRONG HIGH PRESSURE BUILDS INTO THE REGION THROUGH THE
REMAINDER OF THE EXTENDED PERIOD.

&&

.MARINE...

A MODEST SOUTHWEST WIND WILL EMERGE ON TUESDAY IN ADVANCE OF A WEAK
CLIPPER SYSTEM.  THE MAGNITUDE OF THE WINDS WILL REMAIN MUTED GIVEN
A VERY COLD ICE COVERED LAKES REGION. SURFACE WINDS WILL THEN REMAIN
UNORGANIZED OVER THE REGION FOR MUCH OF THE WEEK AS THE AREA WILL BE
IMPACTED WITHIN THE BACKDROP OF A LARGE AREA OF HIGH PRESSURE. THIS
HIGH WILL CERTAINLY BE DISRUPTED AT TIMES AS WEAK AREAS OF LOW
PRESSURE SWING THROUGH...ALTHOUGH ATMOSPHERIC STABILITY WILL BE HIGH
ENOUGH THAT IT WILL SEVERELY LIMIT THE SUCCESS OF THE SURFACE
REFLECTIONS.

&&

.AVIATION...ISSUED 214 PM EST MON MAR 3 2014

//DISCUSSION...

HIGH PRESSURE WILL BRING VFR CONDITIONS TODAY AND TONIGHT. AN UPPER
LEVEL DISTURBANCE WILL TRACK ACROSS THE NORTHERN GREAT LAKES VERY
LATE TONIGHT AND TUESDAY. THIS WILL PROVIDE A CHANCE FOR SNOW OVER
THE AREA...ESPECIALLY NORTH OF THE M-59 CORRIDOR. CONDITIONS WILL BE
FAVORABLE FOR LARGE SNOWFLAKES TO FORM...STARTING AROUND 10Z AT MBS
AND THEN WORKING SOUTHWARD DOWN TO PTK BY LATE MORNING. THIS WILL
LIKELY BRING A QUICK DROP IN VISIBILITIES TO 1-2SM...POTENTIALLY
LOWER...AT MBS AND FNT. SNOW WILL THEN CONTINUE THROUGH THE
AFTERNOON. HEAVIEST ACCUMULATIONS ARE EXPECTED UP TOWARDS
MBS...WHICH COULD SEE ABOUT 1.0-1.5 INCHES. LITTLE OR NO SNOW IS
EXPECTED ACROSS FAR SOUTHERN LOWER MICHIGAN NEAR THE DETROIT
TERMINALS.

FOR DTW...VFR CONDITIONS AND LIGHT WINDS ARE EXPECTED TO PREVAIL
TODAY AND TONIGHT AS SURFACE HIGH PRESSURE MIGRATES OVER THE AREA.
AN UPPER LEVEL DISTURBANCE WILL TRACK ACROSS THE NORTHERN GREAT
LAKES TUESDAY...WITH BEST CHANCES FOR SNOW REMAINING JUST NORTH OF
DTW. A FEW LIGHT SHOWERS ARE POSSIBLE LATE TUESDAY MORNING THROUGH
TUESDAY AFTERNOON HOWEVER. MAIN IMPACT IS EXPECTED TO BE CEILINGS
DROPPING BELOW 5000 FEET IN THE AFTERNOON.

//DTW THRESHOLD THREATS...

* MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FT TUESDAY AFTERNOON.

&&

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

&&

$$

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


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