EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1154 AM EDT FRI MAR 18 2016 VALID 12Z MON MAR 21 2016 - 12Z FRI MAR 25 2016 ...OVERVIEW... THE LOWER 48 MEDIUM PERIOD WILL BE CHARACTERIZED --- AS AN ACTIVE ONE... WITH AN INTENSE SURFACE CYCLONE EXITING NEW ENGLAND ON DAY 3. ANOTHER 'SPRING-LIKE' PACIFIC TROUGH DIGS ACROSS THE GREAT BASIN AND FOUR CORNERS DAYS 5-6...WITH EMBEDDED ENERGY... MOISTURE AND MILD/DRY SOUTHERN HIGH PLAINS-DESERT SOUTHWEST AIR STREAKING NORTHEASTWARD (OUT AHEAD) --- ACROSS THE PLAINS...MIDWEST AND EAST CENTRAL STATES. ANTICIPATE ANOTHER SURFACE CYCLONE TRACK FROM THE SOUTHERN HIGH PLAINS TO CENTRAL GREAT LAKES BY THIS FORECAST PERIOD'S END. ...MODEL PREFERENCES... PREFER TO MAINTAIN THE GENERAL CONSENSUS (ECWMF/CANADIAN/UKMET) --- A NON-GFS DETERMINISTIC SOLUTION FOR THE NOR'EASTER --- DAY 3. AND BY DAY 5-6... THE NON-GFS APPROACH WOULD MAINTAIN A SLIGHTLY SLOWER EJECTION OF A FOUR CORNERS LOW AND BROAD PACIFIC TROUGH --- DOWNWIND OF THE CONTINENTAL DIVIDE. THIS LEADING TO MORE WARM ADVECTION AND WESTERN GULF MOISTURE FOR THE SOUTHEAST QUARTER OF THE NATION --- WITH SEVERAL ROUNDS OF CONVECTIVE INITIATION (AND CLUSTERS OF SHOWERS AND THUNDERSTORMS) MIGRATING EAST-NORTHEASTWARD FROM THE CENTRAL AND SOUTHERN PLAINS TO THE OHIO VALLEY. THAT SAID---A 18/00Z ECENS/NAEFS MEANS APPROACH SHOULD HOLD THE PATTERN IN PLACE FOR POSSIBLE PACIFIC TROUGH SPEED 'ADJUSTMENTS'. A FASTER GFS-TYPE APPROACH WOULD PULL A MORE PRONOUNCED CANADIAN AIRMASS SURGE FROM THE SOUTH CENTRAL CANADIAN PRAIRIE PROVINCES TO THE LOWER HALF OF THE MISSOURI VALLEY BY DAY 6 AND LIMIT THE WESTERN GULF MOISTURE FEED --- IN TERMS OF DURATION AND AREAL COVERAGE. ITS (THE GFS') STRONGER MID-LEVEL SHORTWAVE --- CONSOLIDATES CONSIDERABLY MORE ORGANIZED CONVECTION --- INTO A MORE-PRONOUNCED SURFACE REFLECTION THROUGH NORTHERN NEW ENGLAND ---THAN I MIGHT BE EXPECTING IN THIS FLOW PATTERN. NOT TO SAY A SURFACE WAVE WILL NOT DEVELOP ---JUST DO NOT THINK THE AGGRESSIVENESS OF COLD ADVECTION INTO THE LOWER MISSOURI/WESTERN OHIO VALLEYS --- IS WHERE THE FORECAST SHOULD BE TRENDING WITH THE FOUR CORNERS LOW AND 500MB TROUGH AXIS LOCATION DAY 5-7. ....UNCERTAINTY ASSESSMENT... PARTICULARLY IN THE LATTER PORTION OF THIS MEDIUM RANGE FORECAST PERIOD --- A SLIGHTLY FASTER GFS APPROACH AND RATHER STEADY STREAM OF PACIFIC ENERGY ENTERING THE SOUTHWEST COAST OF CANADA --- BEGINS TO GREATLY ALTER THE DOWNSTREAM PATTERN. AT THIS POINT IN TIME ... WOULD LIKE TO SEE A STRONGER CANADIAN SURFACE HIGH PLUNGING OUT OF THE YUKON FOR DAY 5-6 --- IN THE WAKE OF THIS 'PROJECTED' STEADY PACIFIC MOISTURE STREAM --- TO BELIEVE IT'S WORTH GOING WITH THE GFS APPROACH. IN GENERAL... WILL ANCHOR A FOUR-CORNERS LOW POSITION AT 24/12Z (LIKE ALL THE MEANS DEPICT) AND STAY AWAY FROM AN OUTCOME IN THE MIDWEST THAT LOOKS LIKE THE 18/00Z GFS. BASICALLY...WILL MAINTAIN PREVIOUS SHIFT'S CONTINUITY HERE. THE 18/06Z GFS LOOKS ENOUGH LIKE THE MEANS AND 18/00Z DETERMINISTIC ECMWF/CANADIAN --- TO SUPPORT THE NATIONAL FORECAST PHILOSOPHY GOING FORWARD --- FOR A SERIES OF SHORTWAVES TO EJECT FROM THE PACIFIC TROUGH AXIS. IN THE NORTHEAST ... A SLIGHTLY FASTER GFS (FOR THE DAY 3 NOR'EASTER) CONTINUES TO DRAW THE SURFACE CYCLONE AND ITS DEFORMATION PRECIPITATION SHIELD AWAY FROM THE GULF OF MAINE. WHILE THIS HAS BEEN THE GFS-BASED FORECAST FOR 3-4 DAYS NOW ... THE ECMWF/UKMET AND CANADIAN SUGGEST A WESTERN-EDGED PRECIPITATION SHIELD THAT HAS MORE OF AN IMPACT FOR LAND-BASED INTERESTS OF NEW ENGLAND. PREFER THOSE MORE PESSIMISTIC/AGGRESSIVE APPROACHES TODAY. ESPECIALLY FOR THE COMING EASTER WEEKEND TRAVEL PERIOD. ...SENSIBLE WEATHER HIGHLIGHTS... MILD/WARM AND OCCASIONALLY STORMY FROM THE PLAINS TO THE CENTRAL MISSISSIPPI VALLEY WITH THE NEXT PACIFIC TROUGH MIGRATION THROUGH THE WEST. A TYPICAL SPRING PATTERN IN THE WEST ... WITH A NORTHWEST FLOW THAT CREATES PASSING SHOWERS FROM TIME TO TIME ALONG THE COAST AND WINDWARD COASTAL RANGES. AND BREEZY/WINDY CONDITIONS ACROSS THE INTERIOR (WEST OF THE DIVIDE) WITH SCATTERED 'TERRAIN-HUGGING' RAIN/SNOW SHOWERS AND A COOLER VALLEY TEMPERATURE PROFILE. THE TRACK OF THIS PARTICULAR FOUR CORNERS LOW WILL SET UP AN ACTIVE SOUTHWESTERLY FLOW PATTERN IN THE CENTRAL ROCKIES --- AND LIKELY --- MORE WINTER-LIKE CONDITIONS FOR THE HIGHER ELEVATIONS. VOJTESAK