Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 231928 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 328 PM EDT WED APR 23 2014 .SHORT TERM...
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TONIGHT SURFACE HIGH PRESSURE CENTERED OVER THE WESTERN GREAT LAKES WILL SLIDE OVERHEAD TONIGHT...KEEPING DRY AND QUIET WEATHER OVER SOUTHEAST MICHIGAN. HIGH CLOUDS WILL INCREASE OVERNIGHT AS THE NEXT LOW PRESSURE SYSTEM APPROACHES...WITH SOME MID-LEVEL CLOUDS WORKING IN TOWARDS DAYBREAK. CROSS-SECTIONS OF MODEL MOISTURE...WHICH LOOKS TO BE POSITIONED HIGH BUT EXTEND QUITE DEEP...AND SATELLITE IMAGERY SUPPORT A MOSTLY CLOUDY WORDING BY LATE TONIGHT. AN ELEVATED WARM FRONT AHEAD OF THE LOW ORGANIZING OVER THE PLAINS IS FORECAST TO START WORKING UP ACROSS LOWER MICHIGAN LATE. WILL MAINTAIN A DRY FORECAST WITH THIS AS THE THE LOW-LEVEL JET AND A VERY MODEST SURGE OF THETA-E ADVECTION REMAIN WELL TO OUR WEST. LITTLE CHANGE WAS NECESSARY TO MIN TEMPS AS GOOD RADIATIONAL COOLING CONDITIONS SET UP EARLY IN THE NIGHT BEFORE HIGH CLOUDS MOVE IN. MIN TEMPS SHOULD RANGE FROM THE UPPER 20S TO MID 30S...WARMEST IN THE DETROIT HEAT ISLAND AND WESTERN SECTIONS OF THE FORECAST AREA WHERE CLOUDS WILL ARRIVE AND THICKEN A LITTLE EARLIER.
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&& .LONG TERM...
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MID AND HIGH CLOUDS WILL STREAM ACROSS THE RIDGE AXIS THROUGH THE DAY ON THURSDAY BRINGING A MOSTLY CLOUDY SKY CONDITION, PARTICULARLY THROUGH THE FIRST HALF OF THE DAY. AT THE SAME TIME, EASTWARD PROGRESSION OF THE LARGE SCALE PATTERN WILL FAVOR REBOUNDING HEIGHTS/TEMPS THROUGHOUT THE COLUMN WHICH, COMBINED WITH PROGGED BOUNDARY LAYER GROWTH TO 850MB, SHOULD ALLOW HIGHS TO REBOUND SEVERAL DEGREES OVER TODAY`S HIGHS. SE WINDS WILL, HOWEVER, MAINTAIN A CHILL IN THE AIR IN LAKE SHADOWED REGIONS AND WILL TEMPER EXPECTATIONS TO UPPER 50S OVERALL. RIDGE AXIS WILL TRANSIT SE MICHIGAN LATE THURSDAY, USHERING IN A PERIOD OF INCREASING MID-LEVEL ISENTROPIC ASCENT. THIS WILL SERVE TO MOISTEN THE COLUMN, BUT MODEL SOLUTIONS SUGGEST NOTHING IN THE WAY OF PRECIP WITH THIS INCREASING MOISTURE TRANSPORT/ASCENT. THE SOLUTIONS ARE BELIEVABLE GIVEN THE DEEP LAYER OF REMNANT DRY AIR IN THE LOWEST 12KFT, SO A DRY FORECAST LOOKS TO BE IN ORDER UNTIL THE APPROACH OF THE PRIMARY TROUGH AXIS LATE. OVERALL MODEL DEPICTION OF THURSDAY NIGHT`S SYSTEM CONTINUES TO FAVOR SLOWER SOLUTIONS AS IMPROVING DATA QUALITY ALLOWS FOR BETTER RESOLUTION OF INTERACTING NORTHERN/SOUTHERN WAVES. THE STRONGEST SHORTWAVE FORCING WILL OCCUR WITH THE TWO INDIVIDUAL WAVES, WHICH WILL REMAIN UNPHASED, AND WILL THUS SPLIT THE REGION LEAVING SE MICHIGAN IN A ZONE OF RELATIVELY WEAK/LESS ORGANIZED LARGE SCALE ASCENT. APPROACH OF THE MID-LEVEL TROUGH AXIS WILL HELP TO ORGANIZE DEEP LAYER ISENTROPIC ASCENT, BUT NOT UNTIL CLOSER TO 09Z OR SO. LOW STATIC STABILITY AND STRONGER FORCING BY THIS TIME SHOULD ALLOW SHOWERS TO BEGIN PUSHING INTO THE AREA BY THIS TIME. THE BULK OF THE RAINFALL WILL THEN TRANSIT THE AREA ALONG/AHEAD OF THE ELONGATED 500MB FRONTAL ZONE WHERE SYSTEM RELATIVE FGEN WILL REMAIN FAIRLY ACTIVE. RAPID DEAMPLIFICATION OF THE FLOW IN THE WAKE OF THE TROUGH WILL FAVOR A QUICK EXIT TO PRECIP AS DRY AIR AGGRESSIVELY SPREADS OVER THE REGION MID/LATE MORNING FRIDAY, SO NOT EXPECTING MUCH MORE THAN A 3-4 HOUR PERIOD OF SHOWERS FOR MOST AREAS. THIS WILL ALSO ALLOW MIXING HEIGHTS TO RAPIDLY DEEPEN DURING THE AFTERNOON HOURS RESULTING IN GUSTY WINDS AND TEMPERATURES QUICKLY REBOUNDING FROM THE 40S INTO LOW TO MID 60S. SECONDARY ROUND OF NORTHERN STREAM HEIGHT FALLS WILL USHER A COLD FRONT THROUGH THE AREA FRIDAY NIGHT. EVENTUAL DEVELOPMENT OF A CLOSED LOW OVER THE EASTERN UNITED STATES WILL ENSURE THE CHILLY AIR STAYS IN PLACE FOR THE REMAINDER OF THE EXTENDED.
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&& .MARINE...
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LIGHT TO OCCASIONALLY MODERATE SOUTHEAST FLOW WILL DEVELOP LATE TONIGHT AND PERSIST THROUGH INTO EARLY FRIDAY NIGHT AS A WEAK PRESSURE GRADIENT MAINTAINS RELATIVELY TRANQUIL CONDITIONS ACROSS THE WATERS. WINDS WILL QUICKLY SHIFT TO THE WEST ON FRIDAY BEHIND A WEAK FRONT AND WILL THEN QUICKLY RAMP UP LATE FRIDAY NIGHT AS A STRONGER COLD FRONT MOVES THROUGH THE GREAT LAKES. AS A RESULT...MODERATE NORTHWEST WINDS MAY BE ACCOMPANIED BY GUSTS TO NEAR-GALES THROUGH EARLY SATURDAY.
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&& .AVIATION...
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ISSUED 115 PM EDT WED APR 23 2014 //DISCUSSION... HIGH PRESSURE SETTLING INTO THE REGION WILL BRING VFR CONDITIONS THROUGH 00Z FRIDAY. NORTHERLY WINDS WILL ALSO DECREASE IN SPEED TODAY...WITH GUSTS TO 15 KNOTS DROPPING OFF BY LATE AFTERNOON...BEFORE BECOMING LIGHT AND VARIABLE OVERNIGHT. HIGH/MID CLOUDS WILL INCREASE AND THICKEN OVERNIGHT AND THURSDAY AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. RAIN FROM THIS SYSTEM IS EXPECTED TO HOLD OFF UNTIL AFTER 00Z FRI. //DTW THRESHOLD THREATS... * NONE
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...HLO LONG TERM....JVC MARINE.......JVC AVIATION.....HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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