Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 040441
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1141 PM EST TUE MAR 3 2015


.AVIATION...

SOME BREAKS IN MVFR CEILING ARE EXPECTED AT MBS DOWN TO ABOUT FNT
DURING THE EARLY MORNING BEFORE THE COLD FRONT MOVES INTO THE
REGION. BACKING WIND AHEAD OF THE FRONT WILL LIKELY DELAY A CLEARING
TREND THROUGH THE DTW AREA BUT CEILING WILL LIFT TO BORDERLINE VFR
DURING THE DAYLIGHT HOURS OF THE MORNING AS COLDER AND DRIER AIR
FILTERS INTO THE REGION. SURFACE HIGH PRESSURE BUILDING MORE
STRONGLY INTO LOWER MICHIGAN WILL BRING THE WIND AROUND TO THE NORTH
WEDNESDAY NIGHT. THE WIND DIRECTION AND HIGH PRESSURE ITSELF WILL
HELP SCOUR OUR ANY REMAINING LOW CLOUDS AS THE NIGHT PROGRESSES.

FOR DTW... WESTERLY WIND GUSTING TO 25 KNOTS WILL DIMINISH DURING
THE REST OF THE NIGHT. MVFR CEILING WILL LINGER IN ADVANCE OF THE
COLD FRONT BEFORE IMPROVING SLIGHTLY INTO VFR POST FRONT
DURING THE MORNING.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING BELOW 5000 FT FOR THE REST OF TONIGHT.

&&

.PREV DISCUSSION...ISSUED 940 PM EST TUE MAR 3 2015

UPDATE...

THE EARLIER UPDATE EXPIRED THE REMAINING WINTER WEATHER HEADLINES
AND BUMPED WIND GUSTS UP A BIT DURING THE EVENING. WESTERLY WIND
GUSTING NEAR 30 MPH IS PART OF THE WELL MIXED PSEUDO WARM SECTOR
OF TODAY`S LOW PRESSURE SYSTEM. EXPECT THE GUSTINESS TO DIMINISH
AFTER THE WEAK PREFRONTAL TROUGH PASSAGE AND ADDITIONAL DIURNAL
COOLING OF THE BOUNDARY LAYER. COLD ADVECTION WILL BE WEAK BEHIND
THE TROUGH WHILE THE COLD FRONT TRAILING THE SYSTEM MAKES PROGRESS
THROUGH THE WESTERN GREAT LAKES DURING THE NIGHT. MIN TEMPS
DROPPING BACK INTO THE 20S IN THE GOING FORECAST LOOKS REASONABLE
BEFORE THE FRONT ARRIVES IN SE MICHIGAN AROUND SUNRISE. COLD
ADVECTION WILL GAIN ENOUGH TRACTION DURING THE MORNING TO ONLY
ALLOW A FEW DEGREES OF WARMING BEFORE TEMPERATURES HOLD STEADY OR
BEGIN TO FALL FROM THE MID AND UPPER 20S THROUGH THE REST OF
WEDNESDAY.

PREV DISCUSSION...ISSUED 258 PM EST TUE MAR 3 2015

SHORT TERM...TONIGHT

A SOLID 1 TO 3 INCHES OF SNOW FELL ACROSS THE MAJORITY OF
SOUTHEAST MICHIGAN...TOPPED OFF WITH SLEET AND FREEZING RAIN.
MID LEVEL DRY SLOT HAS ARRIVED...EFFECTIVELY PUTTING AN END TO THE
APPRECIABLE PRECIPITATION. WEAK SURFACE LOW NOW PUSHING INTO
NORTHERN LOWER MICHIGAN LATE THIS AFTERNOON AS
UPPER LEVEL SHORTWAVE TRACKS THROUGH THE STRAIGHTS.
SOUTHERLY WINDS ADVECTING MILDER AIR INTO SOUTHERN LOWER
MICHIGAN...AND STILL EXPECTING TEMPS TO REACH AND RISE ABOVE
32 DEGREES DURING THE RUSH HOUR. ALLOWING THE WINTER WEATHER
ADVISORY FOR SOUTHERN FOUR COUNTIES TO EXPIRE AT 4 PM...WITH THE
OTHER ADVISORY HOLDING TIL 7 PM. WEAK SURFACE CONVERGENCE ALONG THE
COLD FRONT THIS EVENING STILL MAY BE SUFFICIENT TO WRING OUT
DRIZZLE/FREEZING DRIZZLE...BUT FOR THE MOST PART...TONIGHT WILL BE
UNEVENTFUL WITH LIGHT WESTERLY POST FRONTAL FLOW AND GRADUALLY
LOWERING TEMPERATURES. DEEPER (925 MB) LOW LEVEL COLD AIR DOES NOT
ARRIVE UNTIL RIGHT AROUND 12Z WEDNESDAY...MAKING MINS A BIT
CHALLENGING...AND FAVOR TEMPS HOLDING IN THE UPPER TEENS FAR
NORTH TO MID 20S SOUTH AS CLOUDS PERSIST OVERNIGHT.

LONG TERM...WEDNESDAY THROUGH NEXT TUESDAY

THERE HAS BEEN A NOTED TREND TOWARD SLIGHTLY LESS PROGRESSION OF THE
LONG WAVE TROUGH PUSHING INTO THE WESTERN GREAT LAKES WED AND WED
NIGHT. DEEP LAYER FGEN AND MOISTURE WILL STILL RESIDE WELL SOUTH OF
THE STATE...WITH PERSISTENT LOW LEVEL COLD AIR ADVECTION ACROSS
LOWER MI. THE NAM...CANADIAN AND TO SOME EXTENT ECMWF HOLD SOME
LINGERING SFC TROUGHING BACK ACROSS CNTL MI THROUGH WED AFTERNOON
WITH DEEP LAYER W-SW IN PLACE ALOFT. UPSTREAM OBSERVATIONS SUGGEST
THERE WILL BE SOME RESIDUAL LOW LEVEL MOISTURE IN PLACE ACROSS LOWER
MI. THE ADDED LOW LEVEL CONVERGENCE ASSOCIATED WITH THE TROUGH AND
STEEPENING LOW LEVEL LAPSE RATES DUE TO 925-850MB COLD AIR ADVECTION
AND DAYTIME HEATING WILL SUPPORT A SLIGHT CHANCE OF SNOW SHOWERS
ACROSS THE SAGINAW VALLEY AND THUMB WED AFTERNOON. THIS TROUGH AXIS
SHOULD SLIDE SE OF THE FORECAST AREA WED NIGHT ALLOWING LOW LEVEL
COLD AIR TO MAKE A STRONGER PUSH INTO LOWER MI. 850MB TEMPS ARE
STILL EXPECTED TO DROP TO -20 TO -22C BY THURS MORNING. A GOOD DEAL
OF MID/HIGH CLOUDS SHOULD STREAM ACROSS THE FORECAST AREA WED NIGHT
INTO AT LEAST THURS MORNING...TEMPERING WED NIGHT MINS TO THE SINGLE
DIGITS. THE DEEP LAYER COLD AIR WILL PERSIST OVER SE MI INTO EARLY
FRI MORNING...SUPPORTING A CONTINUATION OF WELL BELOW NORMAL TEMPS
AND SUB ZERO WIND CHILLS THURS NIGHT INTO FRI MORNING.

SOME MODEST WARMING WILL OCCUR ON FRIDAY AS THE CORE OF THE ARCTIC
AIR SLIDES EAST. A BROAD LONG WAVE TROUGH WILL REMAIN IN PLACE
ACROSS ERN CANADA AND THE GRT LKS THROUGH THE WEEKEND WHICH WILL
STILL HOLD TEMPS BELOW EARLY MARCH MEANS. NUMEROUS MID LEVEL SHORT
WAVE IMPULSES CONTINUE TO BE SHOWN BY BOTH THE GFS AND ECMWF TO
IMPACT THE REGION FRI THROUGH MON. CONTINUED DIFFERENCES IN TIMING
AND AMPLITUDE AND POOR RUN TO RUN CONTINUITY WITH THESE FEATURES
WILL LIKELY PERSIST FOR SEVERAL MORE MODEL CYCLES. THE AIRMASS
OVERALL WILL BE QUITE DRY...SUPPORTING NOTHING MORE THEN SLIGHT
CHANCE TYPE POPS THROUGH THIS PERIOD ATTM. THE MEDIUM RANGE MODEL
SUITE DO HOWEVER REMAIN CONSISTENT IN SHOWING THE TROUGH-RIDGE
PATTERN OVER NOAM... WHICH HAS BEEN SO DOMINATE THE LAST SEVERAL
WEEKS...BREAKING DOWN NEXT WEEK. THIS SUGGESTS BUILDING HEIGHTS
ACROSS LOWER MI AND THE POTENTIAL FOR A MORE SUBSTANTIAL WARMING
TREND.

MARINE...

WINDS WILL VEER FROM S-SE TO WEST THIS EVENING AS LOW PRESSURE LIFTS
NORTHEAST OF THE STRAITS REGION. WINDS WILL ACTUALLY WEAKEN DURING
THE FIRST HALF OF THE NIGHT AS SOME RESIDUAL TROUGHING LINGERS OVER
LAKE HURON. WESTERLY WINDS WILL INCREASE EARLY WED MORNING AS
ANOTHER SURGE OF ARCTIC AIR ADVANCES INTO THE REGION. THE WINDS
SHOULD BE STRONGEST ACROSS NORTHERN LAKE HURON AS SOME DEGREE OF
LINGERING SURFACE TROUGH IS EXPECTED ACROSS THE SOUTHERN HALF OF THE
LAKE INTO WED AFTERNOON. WINDS WILL THEN DECREASE LATE WED INTO
THURS AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST.

&&

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

$$

AVIATION.....99
UPDATE.......BT
SHORT TERM...SF
LONG TERM....SC
MARINE.......SC


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).


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