000 FXUS63 KDTX 101124 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 624 AM EST WED FEB 10 2010 .AVIATION... CONDITIONS GRADUALLY IMPROVING THIS MORNING AS SNOW CONTINUES TO DIMINISH IN COVERAGE AND INTENSITY. LINGERING IFR/MVFR VISIBILITY IN LIGHT SNOW WILL CONTINUE FOR ANOTHER 2-3 HOURS BEFORE THE SNOW TAPERS OFF. WINDS WILL STRENGTHEN TODAY OUT OF THE NORTH IN THE WAKE OF THE DEPARTING WINTER STORM WITH GUSTS OF 20-25 KNOTS COMMON. THIS WILL LEAD TO A PROLONGED PERIOD OF BLOWING AND DRIFTING SNOW TODAY. WINDS WILL DIMINISH WHILE VEERING TO THE NORTHWEST OVERNIGHT AS THE PRESSURE GRADIENT RELAXES. VFR/HIGH MVFR STRATUS WILL PERSIST FOR THE REMAINDER OF THE TAF PERIOD. && .PREV DISCUSSION...ISSUED 430 AM EST WED FEB 10 2010 SHORT TERM...TODAY EXPANSIVE AREA OF LIGHT TO MODERATE SNOW DRIVEN BY PERSISTENT ISENTROPIC ASCENT AND MID LEVEL DEFORMATION FORCING ENCOMPASSING THE ENTIRE FORECAST AREA. THE HEAVIEST SNOWFALL NOW WORKING ACROSS THE NORTHWEST PORTIONS OF THE WARNING AREA AS THE DEFORMATION STARTS TO PIVOT ON THE NORTHWEST FLANK OF THE MID LEVEL PV ANOMALY SHIFTING ACROSS SOUTHERN OHIO. IN ADDITION...RADAR CONTINUES TO DEPICT A PERSISTENT AREA OF MODERATE SNOW EXTENDING FROM THE SAGINAW BAY SOUTHWEST THROUGH SOUTHERN BAY/SAGINAW AND NORTHERN SHIAWASSEE COUNTIES. THIS WOULD SUGGEST SOME ADDITIONAL ENHANCED LOW LEVEL CONVERGENCE WITH A POSSIBLE LAKE COMPONENT AS THE FLOW RUNS PARALLEL TO THE BAY. RADAR ESTIMATES AND RECENT SPOTTER REPORTS INDICATE SNOWFALL RATES OF UP TO AN INCH PER HOUR AT TIMES. SNOW RATIOS THUS FAR THROUGH THE EVENT HOLDING IN THE 15:1 RANGE. LATEST HIRES WRF SEEMS TO CAPTURE ONGOING TRENDS THE BEST AND DEPICTS A MATURE/WEAKENING DEFORMATION ZONE ROTATING EAST-SOUTHEAST ACROSS THE AREA THROUGH THE MID-LATE MORNING HOURS. IT ALSO CAPTURES THE ONGOING LOCALIZED BAND WORKING OFF THE BAY AND SUSTAINS THIS ACTIVITY FOR SEVERAL MORE HOURS. IN LIGHT OF THIS AND GIVEN CURRENT RADAR TRENDS...RECENT REPORTS AND LATEST OBSERVATIONS WILL GO AHEAD AND UPGRADE BAY COUNTY FOR A SHORT DURATION WARNING THROUGH THE MID MORNING HOURS. CALLS AROUND THIS AREA INDICATE AT LEAST 5-7 INCHES OVER THE SOUTHERN PART OF THE COUNTY WITH SUBSTANTIAL BLOWING AND DRIFTING...WITH THE POTENTIAL FOR AN ADDITIONAL 2-3 INCHES ACROSS THE SOUTHEASTERN CORRIDOR OF THE COUNTY /INCLUDING BAY CITY/. ELSEWHERE...SNOWFALL INTENSITY/COVERAGE WILL CONTINUE TO DIMINISH WITH TIME AS THE FORCING WEAKENS. AN ADDITIONAL 1-2 INCHES STILL LOOKS ATTAINABLE AS THIS PROCESS UNFOLDS...ESPECIALLY ALONG THE I-75 CORRIDOR. A BACKING FLOW TOWARD THE NORTH-NORTHEAST WILL ALSO INTRODUCE A SLIGHT LAKE COMPONENT FOR THE EASTERN THUMB TODAY... ALTHOUGH THE THERMODYNAMIC SETUP REMAINS UNIMPRESSIVE /SUB 4K FT INVERSION HEIGHTS AND 850 MB TEMPS WARMER THAN -10C/ SO THE CONTRIBUTION APPEARS TO BE LIMITED. LIGHT SNOW WILL TRANSITION TO SCATTERED SNOW SHOWERS INTO THE AFTERNOON AS THE MID LEVEL CIRCULATION HEADS TOWARD THE EAST COAST. CONSIDERABLE BLOWING AND DRIFTING OF SNOW WILL CONTINUE THROUGH THE DAY WITH A TIGHT PRESSURE GRADIENT ENSURING NORTHERLY GUSTS REACH 30 MPH AT TIMES. THIS WILL ALSO CONTRIBUTE TO SINGLE DIGIT WIND CHILL READINGS INTO THE AFTERNOON AS TEMPERATURES HOVER IN THE 20S. LONG TERM...TONIGHT THROUGH NEXT TUESDAY THE LONG TERM FORECAST WILL FEATURE A COOL AND DRY NORTHWESTERLY FLOW AS THE NEXT LONGWAVE TROUGH SETS UP ACROSS THE EASTERN UNITED STATES. INITIALLY...SURFACE HIGH PRESSURE WILL TRY TO BUILD INTO THE WESTERN GREAT LAKES ON THURSDAY BUT BROAD CYCLONIC FLOW ASSOCIATED WITH THE DEPARTING LOW PRESSURE SYSTEM WILL CONTINUE TO HAVE AN INFLUENCE OVER THE REGION INTO FRIDAY. CLOUDS MAY BRIEFLY SCATTER OUT ON THURSDAY MORNING BUT SKY CONDITIONS WILL CONTINUE TO FLUCTUATE BETWEEN PARTLY TO MOSTLY CLOUDY SKIES THROUGH THE REMAINDER OF THE WEEK. THE TWO FEATURES TO WATCH FOR THE WEEKEND INCLUDE A WEAK CLIPPER APPROACHING FROM WESTERN CANADA AND THE NEXT UPPER LOW DROPPING SOUTH ACROSS CANADA FROM THE ARCTIC. SOME DIFFERENCES DO EXIST BETWEEN THE LONG RANGE MODELS BUT GENERALLY PREFER THE ECMWF/UKMET WHICH EVENTUALLY CARVE OUT A DEEPER TROUGH AND PUSH THE PREVAILING STORM TRACK SOUTH OF THE OHIO VALLEY. ANY SNOW ASSOCIATED WITH THE CLIPPER IS EXPECTED TO BE BOTH LIGHT AND LARGELY REMAIN SOUTH OF THE STATE LINE SO THE GOING FORECAST WITH JUST A CHANCE OF SNOW STILL LOOKS GOOD. MARINE... GALE FORCE WINDS WILL CONTINUE TODAY AS THE LOW PRESSURE SYSTEM OVER EASTERN LAKE ERIE PULLS AWAY TO THE EAST COAST. FREQUENT GUSTS TO 35 KNOTS CAN BE EXPECTED BEFORE WIND GRADUALLY DECREASE LATE THIS AFTERNOON INTO TONIGHT. THE STRONG WINDS AND BUILDING WAVES WILL CONTRIBUTE TO FREEZING SPRAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING...MIZ055-MIZ062-MIZ063...UNTIL 1 PM WEDNESDAY. WINTER STORM WARNING...MIZ048-MIZ053-MIZ054-MIZ060-MIZ061-MIZ068- MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-MIZ083...UNTIL 10 AM WEDNESDAY. WINTER WEATHER ADVISORY...MIZ047...UNTIL 10 AM WEDNESDAY. WINTER WEATHER ADVISORY...MIZ049...UNTIL 1 PM WEDNESDAY. LAKE HURON... GALE WARNING...LHZ362-LHZ363-LHZ421-LHZ422-LHZ441-LHZ442-LHZ443- LHZ462-LHZ463-LHZ464...UNTIL 7 PM WEDNESDAY. LAKE ST CLAIR... BRISK WIND ADVISORY...UNTIL 4 PM WEDNESDAY. MI WATERS OF LAKE ERIE... BRISK WIND ADVISORY...UNTIL 4 PM WEDNESDAY. && $$ AVIATION.....MR SHORT TERM...MR LONG TERM....KEC MARINE.......KEC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).