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000
FXUS63 KDTX 240803
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
303 AM EST SAT JAN 24 2015

.SHORT TERM...TODAY AND TONIGHT

BENIGN WEATHER EXPECTED DESPITE THE INFLUENCE OF SEVERAL SHORTWAVES
WITHIN NORTHWEST UPPER FLOW OVER THE NEXT 24 HOURS. THE FIRST SUCH
WAVE IS PUSHING ACROSS THE STATE EARLY THIS MORNING AND BECOMING
INCREASINGLY SHEARED ALONG THE BACKSIDE OF THE DEVELOPING EAST COAST
CYCLONE. THE ASSOCIATED SURFACE TROUGH IS SUPPORTING BRIEF LIGHT
SNOW SHOWERS, AS EXPECTED, AND WILL CLEAR THE AREA THIS MORNING.

TRANSITION TO WESTERLY FLOW AT THE SURFACE WILL TAKE SHAPE IN THE
WAKE OF THE SURFACE TROUGH AS THE WAVE OVER THE DAKOTAS/MN AT 07Z
THIS MORNING APPROACHES THE GREAT LAKES. MODERATE MID-LEVEL THETA-E
ADVECTION WILL ACCOMPANY THE PASSAGE OF THIS WAVE DURING THE MIDDAY
PERIOD WHICH SHOULD, AT THE VERY LEAST, ENSURE PERSISTENCE OF LOW
CLOUD COVER DURING THE LATTER HALF OF THE DAY. WARM ADVECTION WILL
ALSO BE SUFFICIENT TO PUSH HIGH TEMPERATURES ABOVE FREEZING AND
SUPPORT A FEW BRIEF RAIN/SNOW SHOWERS OR PERHAPS EVEN A PERIOD OF
DRIZZLE GIVEN THE SHALLOW MOISTURE DEPTH AND RELATIVELY WARM COLUMN
ABOVE THE SURFACE. HIGHER RESOLUTION GUIDANCE SUGGEST THE GREATEST
DRIZZLE POTENTIAL WILL FOCUS NEAR/ALONG THE GLACIAL RIDGE.

DEEPER COLD AIR WILL SURGE INTO FORECAST AREA BEHIND THIS SECOND
SHORTWAVE AS A TRAILING WAVE ANCHORED BY THE BROADER SCALE TROUGH
OVER NORTHERN ONTARIO RACES THROUGH THE AREA TONIGHT. WINDS WILL
TURN DECIDEDLY NORTHERLY IN THE 00-06Z PERIOD AND TEMPERATURES WILL
BEGIN TO PLUMMET FROM THE LOW 30S INTO THE LOW 20S...PERHAPS UPPER
TEENS ACROSS THE NORTH. COLD FRONTAL PASSAGE WILL ONCE AGAIN BE
LARGELY DRY BUT A FEW SNOW SHOWERS ARE NOT OUT OF THE QUESTION.
COOLING THERMODYNAMIC PROFILE WILL BE INCREASINGLY FAVORABLE FOR
DENDRITE PRODUCTION AS MODESTLY UNSTABLE AIR OVER LAKE HURON
ENCROACHES ON THE THUMB. A BRIEF BOUT OF DISORGANIZED LAKE EFFECT
SNOW SHOWERS IS PLAUSIBLE, BUT CONTINUALLY VEERING WIND FIELD WILL
LIMIT POTENTIAL. INTRODUCED A CHC POP FOR HURON/SANILAC COUNTIES
LATE TONIGHT FOR A COUPLE TENTHS OF ACCUMULATION POTENTIAL.

FINALLY, DEPENDING ON THE SOUTHWARD PROGRESS OF THE COLD FRONT,
LEADING AREA OF HEIGHT FALLS ASSOCIATED WITH THE CLIPPER COULD
ACTIVATE MID-LEVEL PORTION OF THE FRONT JUST ENOUGH TO SUPPORT A
BAND OF LIGHT SNOW NEAR THE OHIO BORDER TOWARD SUNDAY MORNING.
POTENTIAL IS ON THE LOW SIDE, BUT WORTH A CHANCE POP ATTM AS VARIOUS
MEMBERS OF THE GUIDANCE DO SUPPORT THE SCENARIO.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY

CLIPPER SYSTEM FOR SUNDAY HAS CONTINUED TO TREND FURTHER SOUTH
WITH THE 00Z CYCLE GUIDANCE WITH ONLY THE FAR SOUTHERN CWA...I 94
SOUTH NOW EXPECTED TO RECEIVE LIGHT SNOW ACCUMULATIONS. THE BETTER
FGEN FORCING WILL REMAIN SOUTH OVER THE OHIO VALLEY AS LOW
PRESSURE DROPS SOUTHEAST OF THE AREA. WILL ADJUST SNOW
CHANCES/AMOUNTS DOWNWARD TO THE NORTH OF I-94 OR SO...BUT MAINTAIN
LIKELY SNOW WORDING OVER THE FAR SOUTH WHERE AN INCH TO LOCALLY
TWO NEAR THE MICHIGAN AND OHIO STATE LINE WILL BE POSSIBLE.

WITH THE SHIFT SOUTHWARD...ARCTIC AIRMASS POISED JUST TO THE NORTH
WILL SEEP INTO THE AREA A DAY EARLIER THAN PREVIOUSLY EXPECTED...SO
HIGHS ON SUNDAY WILL ONLY REACH THE LOWER 20S OVER THE NORTHERN CWA
AND MID/UPPER 20S NEARER THE SNOW/THICKER CLOUDS OVER THE FAR SOUTH.

COLD WEATHER WILL PERSIST INTO MONDAY AND TUESDAY AS UPPER LEVEL
TROUGH OVER THE EASTERN CONUS AMPLIFIES AS THIS CLIPPER DEVELOPS
INTO A MORE NOTABLE STORM SYSTEM NEAR THE EASTERN SEABOARD. HIGHS
WILL HOLD AT 20F OR LESS MONDAY AND ONLY REACH THE LOWER 20S ON
TUESDAY WITH LOWS IN THE SINGLE DIGITS BOTH NIGHTS.

MODERATION IN TEMPERATURES IS STILL EXPECTED IN THE WEDNESDAY TO
THURSDAY TIME FRAME AS UPPER TROUGH SHIFTS EAST AND A SHORTWAVE OF
PACIFIC ORIGIN PROGRESSES EAST ALONG THE SOUTHERN EDGE OF THE POLAR
STORM TRACK...WHICH WILL LIE VERY NEAR THE AREA. TEMPERATURES WILL
CLIMB BACK INTO THE 30S BY THURSDAY WITH ANOTHER CHANCE OF SNOW AS
THIS SYSTEM WORKS INTO THE AREA. THIS PERIOD OF NEAR AVERAGE LATE
JANUARY WEATHER WILL BE BRIEF AS MUCH COLDER AIR BEGINS TO SEEP INTO
THE AREA IN THE WAKE OF THIS SYSTEM LATE IN THE WEEK. THE CURRENT
INDICATIONS SUGGEST THAT THIS SHIFT BACK TO COLDER AIR MAY JUST BE
THE BEGINNINGS OF A NOTABLE ARCTIC OUTBREAK HEADING INTO EARLY
FEBRUARY.

&&

.MARINE...

WEST TO SOUTHWEST WINDS WILL SHIFT TO NORTHWEST TODAY AS A COLD
FRONT SETTLES SOUTH THROUGH THE CENTRAL GREAT LAKES. WINDS WILL THEN
VEER TO THE NORTH/NORTHEAST. WIND GUSTS UP TO 30 KNOTS WILL CAN BE
EXPECTED AGAIN THIS AFTERNOON INTO THIS EVENING...BUT GALES ARE NOT
EXPECTED.

WHILE ONSHORE NORTHEAST FLOW WILL PERSIST FROM TONIGHT THROUGH
SUNDAY...WAVE DEVELOPMENT WILL BE HAMPERED BY EXTENSIVE ICE COVER
OVER THE NEAR SHORE WATERS. HENCE...SMALL CRAFT ADVISORIES WILL NOT
BE NEEDED. ONLY SMALL PORTIONS OF THE MARINE ZONES OFF THE TIP OF
THE THUMB SHOW ANY NOTABLE OPEN WATER...BUT EVEN HERE WAVES WILL BE
MUTED.

EARLY NEXT WEEK...CONDITIONS WILL REMAIN RELATIVELY CALM WITH WIND
GUSTS REMAIN AOB 20 KNOTS OVER THE LAKE HURON OPEN WATERS AS SEVERAL
HIGH PRESSURE CENTER BUILD ACROSS THE AREA.

&&

.AVIATION...ISSUED 1157 PM EST FRI JAN 23 2015

PERSISTENT MOIST LOW LEVEL SOUTHWEST FLOW WILL FAVOR A GREATER
COVERAGE OF LOWER STRATUS THROUGHOUT THE MORNING PERIOD.  SOME
POCKETS OF CLEAR SKY MAY EMERGE AT TIMES AS THIS MOISTURE WORKS
AGAINST A DEEP DRY LAYER JUST ABOVE THE INVERSION.  CEILINGS WILL
REMAIN WITHIN MVFR THROUGH THIS TIME.  A WEAK FRONTAL PASSAGE WILL
PROVIDE A LIMITED POTENTIAL FOR LIGHT SNOW SHOWERS AND/OR DRIZZLE
EARLY ON SATURDAY...PROBABILITY TOO LOW TO MENTION AT THIS TIME.  A
SECONDARY FRONT WILL BRING A WIND SHIFT TO NORTHWEST BY EVENING.
THE ENSUING COLD AIR ADVECTION WILL MAINTAIN SOME DEGREE OF MVFR
STRATUS HEADING BEYOND SUNSET.

//DTW THRESHOLD PROBABILITIES...

* HIGH IN CEILINGS BELOW 5000 FEET THROUGH SATURDAY.

&&

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

$$

SHORT TERM...JVC
LONG TERM....DG
MARINE.......DG
AVIATION.....MR


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