EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1211 AM EST SUN NOV 23 2014 VALID 12Z WED NOV 26 2014 - 12Z SUN NOV 30 2014 ...ANOTHER COLD OUTBREAK FOR THE EAST... ...POSSIBLE SNOW WEDNESDAY FOR THE MID ATLANTIC AND NORTHEAST... RELIED ON THE 12Z/22 EUROPEAN CENTRE ENSEMBLE MEAN AS A SYNOPTIC GUIDE THIS FORECAST PERIOD. THE ECENS MEAN HAS BEEN MARKED BY A STEADY SHARPENING OF ITS DEPICTION OF THE FLOW ACROSS THE UNITED STATES AT THE MEDIUM RANGE, WITH THE 12Z/22 VERSION INDICATING A MODEST CHANCE OF ACCUMULATING SNOW FOR PARTS OF THE MID ATLANTIC AND NORTHEAST ON WEDNESDAY--THE BUSY TRAVEL DAY BEFORE THANKSGIVING. HOW FAR WEST A WAVE TRACKS AS IT EMERGES FROM THE EASTERN GULF OF MEXICO OFF THE SOUTHEASTERN ATLANTIC COAST TUESDAY NIGHT IS KEY TO WHETHER RAIN AND SNOW SPREAD INTO THE METROPOLITAN CORRIDOR FROM WASHINGTON TO BOSTON--OR EVEN FARTHER INLAND TO INCLUDE THE APPALACHIANS--WEDNESDAY AND WEDNESDAY NIGHT. A CLIPPER SYSTEM DIVING INTO THE UPPER MIDWEST WEDNESDAY IS AN IMPORTANT PIECE IN THE EASTERN PUZZLE, AS ITS TRAJECTORY AND THE ATLANTIC ONES ARE ALMOST CERTAINLY LINKED BASED ON THE SPREAD OF OUTCOMES SEEN AMONG THE VARIOUS OPERATIONAL MODELS AND INDIVIDUAL ENSEMBLE MEMBERS. WHATEVER THE INTERACTION BETWEEN THE TWO SYSTEMS, ANOTHER NOVEMBER ARCTIC OUTBREAK SEEMS DESTINED FOR THE UPPER MIDWEST AND ACROSS THE GREAT LAKES. THE WEST COAST RIDGE SHOULD GRADUALLY ERODE THROUGH THE PERIOD--THOUGH ITS MEAN POSITION SEEMS ANCHORED. THE SLOW EROSION SHOULD RESULT IN A SENSIBLE UPTICK IN PRECIPITATION FROM CALIFORNIA TO WASHINGTON STATE, WITH THE WARM CONDITIONS AT THE START OF THE PERIOD IN SOUTHERN CALIFORNIA GIVING WAY TO A SEASONABLE COOLNESS BY NEXT WEEKEND. CISCO