000 FXUS63 KDTX 072337 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 637 PM EST SAT NOV 7 2009 .AVIATION... WIND GUSTS HAVE DIED OFF ALREADY THIS EVENING WITH LIGHT AND VARIABLE WINDS DEVELOPING OVERNIGHT. THIS WILL OCCUR AS HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING SURFACE TROUGH. ALTHOUGH A SHALLOW INVERSION HAS DEVELOPED...DO NOT EXPECT MUCH IN THE WAY OF HAZE OVERNIGHT WITH VFR CONDITIONS CONTINUING INTO SUNDAY. A WARM FRONT IS EXPECTED TO LIFT NORTH ACROSS THE AREA SUNDAY AFTERNOON BRINGING INCREASING CIRRUS AND A SCT DECK OF 3000-4000 FOOT CLOUDS. && .PREV DISCUSSION...ISSUED 346 PM EST SAT NOV 7 2009 SHORT TERM...TONIGHT WEAK MOISTURE STARVED COLD FRONT OVER LAKE MICHIGAN WILL GRADUALLY WASH OUT BY THE TIME IT GETS TO SOUTHEAST MICHIGAN. WEAK HIGH PRESSURE RIDGING WILL SLIDE OVERHEAD TONIGHT MAINTAINING CLEAR SKIES AND PRODUCING LIGHT WINDS. DRY AIR ADVECTION WILL BRING DEWPOINTS INTO THE UPPER 30S TO THE 40S ACROSS THE AREA. WITH CLEAR SKIES AND LIGHT WINDS LOWS WILL RADIATE DOWN TO THE DEW POINT WITH PATCHY GROUND FOG AROUND THE AREA BY DAWN. LONG TERM...SUNDAY THROUGH SATURDAY LOW LEVEL RIDGE AXIS IN PLACE TO BEGIN SUNDAY WILL LIFT NORTH THROUGH THE DAY WHILE SSE LOW LEVEL FLOW INCREASES. SLIGHTLY DEEPER MIXING OF THIS MILD RESIDENT AIRMASS WILL AGAIN ALLOW TEMPERATURES TO CLIMB INTO THE LOW-MID 60S. MODELS STILL SUGGESTING A PERIOD OF STRATUS DEVELOPMENT FOR THE AFTERNOON/EVENING AS LOW LEVEL MOISTENING BRINGS DEWPOINTS UP NEAR 50F. WEAK BROAD ASCENT MAY PROVE SUFFICIENT ENOUGH TO GENERATE SOME CLOUD COVER...BUT MUCH LIKE TODAY MODELS SEEM TO BE OVERPLAYING THIS DEVELOPMENT SO WILL LEAN MORE CONSERVATIVE WITH A TREND FROM MOSTLY TO PARTLY SUNNY THROUGH THE EVENING. SHORTWAVE ENERGY SHOWN ON THE LATEST WATER VAPOR APPROACHING THE PACIFIC NORTHWEST WILL SHEAR EASTWARD OVER THE NEXT COUPLE DAYS...AMPLIFYING AS IT REACHES THE GREAT LAKES MONDAY NIGHT/ TUESDAY. MEANWHILE A SOUTHERN STREAM JET MAX WILL LIFT NORTHEAST OUT OF THE SOUTHERN PLAINS AT THE SAME TIME. THE POTENTIAL FOR PHASING OF THIS FLOW STILL CREATING A BROADER SPECTRUM OF SOLUTIONS WITHIN THE SHORT RANGE MODEL GUIDANCE. LATEST NAM NOW BACK TO A LESS-PHASED/ WEAKER/PROGRESSIVE SOLUTION...DRIVING THE ASSOCIATED COLD FRONT THROUGH ON MONDAY. THE GFS HOLDS THE OPPOSITE END OF THE SPECTRUM IN DEPICTING A MUCH SLOWER/DEEPER SYSTEM...WITH STRONG FRONTAL DYNAMICS LARGELY IMPACTING THE AREA LATE MONDAY NIGHT INTO TUESDAY. GIVEN THE POOR CONTINUITY OF THESE MODELS...FAVOR GOES TO THE CONSISTENT ECMWF FOR THE DETAILS. COLD FRONT WILL DROP THROUGH THE AREA MONDAY NIGHT/TUESDAY MORNING...ACCOMPANIED BY A REGION OF STRONG MID LEVEL FRONTOGENESIS/ DEFORMATION IN THE PRESENCE OF GOOD JET COUPLING. MODEL CROSS SECTIONS STILL DISPLAY AN AREA OF ELEVATED INSTABILITY WITHIN THIS LAYER. OVERALL MOISTURE FIELDS LOOKING SLIGHTLY BETTER NOW...WHICH WOULD EASILY SUPPORT AN AXIS OF RAINFALL DEVELOPING GIVEN THE STRENGTH OF THE FRONTAL CIRCULATION DURING THIS TIME. THE POOR CONSENSUS ON TIMING WILL PREVENT POPS FROM BEING ELEVATED BEYOND CHANCE AT THIS POINT. AIRMASS ON MONDAY WILL CHANGE LITTLE FROM THIS WEEKEND UNDER PERSISTENT PRE-FRONTAL SOUTHWEST FLOW...SO ONE FINAL DAY OF LOW-MID 60S. STRONG POST-FRONTAL COLD AIR ADVECTION WILL BRING TEMPERATURES BACK CLOSER TO NORMAL /AROUND 50/ BY TUESDAY. A PERIOD OF CONFLUENT UPPER LEVEL NORTHWEST FLOW WILL DEVELOP TUESDAY NIGHT INTO WEDNESDAY AS STRONG HIGH PRESSURE BUILDS IN AT THE SURFACE. LOW LEVEL GRADIENT MAY STAY UP JUST ENOUGH TO PREVENT IDEAL RADIATIONAL COOLING OVERNIGHT...BUT THE DEGREE OF DRYING IN THE MID LEVELS OF AN ALREADY COOL RESIDENT AIRMASS WOULD STILL SUPPORT MAINTAINING LOWS BELOW SUGGESTED MODEL GUIDANCE TUESDAY NIGHT. SLIGHT RESPONSE IN THE THERMAL FIELDS ON WEDNESDAY AS WEAK SOUTHERLY RETURN FLOW DEVELOPS LATE ON THE BACKSIDE OF THE DEPARTING HIGH. LIMITED MIXING AND STRONG SUBSIDENCE WILL BRING SUNNY CONDITIONS WHILE KEEPING THE TEMPERATURE RECOVERY RELATIVELY IN CHECK /HIGHS MID 40S TO AROUND 50F/. A MORE AMPLIFIED UPPER LEVEL FLOW WILL BEGIN TO EVOLVE TOWARD THE END OF THE WEEK AND CARRY INTO NEXT WEEKEND. STRONG SHORTWAVE ENERGY WILL DEEPEN AS IT DROPS SOUTHEAST ACROSS THE WESTERN CONUS WHILE UPPER HEIGHTS BUILD DOWNSTREAM. THE TYPICAL UNCERTAINTIES EXIST AT THIS TIMESCALE WITH REGARD TO THE SPECIFICS OF THIS PATTERN EVOLUTION. A GENERAL CONSENSUS INDICATES SOUTHEAST LOWER MI WILL RESIDE WITHIN THE NORTHERN EXTENT OF DEEPENING SOUTHWESTERLY FLOW INTO FRIDAY AS A MEAN BAROCLINIC ZONE DEVELOPS ACROSS THE PLAINS/UPPER MISS VALLEY...ALLOWING TEMPERATURES TO AGAIN CLIMB ABOVE NORMAL. ORGANIZED ASCENT WILL REMAIN LARGELY NORTH OF THIS BOUNDARY THROUGH FRIDAY MAINTAINING DRY CONDITIONS LOCALLY DURING THIS TIME. MARINE... WEAKENING COLD FRONT AND SURFACE GRADIENT WILL ALLOW WINDS TO DIE DOWN QUICKLY THIS EVENING ALLOWING FOR SMALL CRAFT ADVISORIES TO EXPIRE. NEXT SHOT AT WIND ISSUES ON THE WATERS WILL COME TUESDAY INTO WEDNESDAY AS A COLD FRONT PUSHES THROUGH THE REGION. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....KEC SHORT TERM...DRC LONG TERM....MR MARINE.......DRC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).