EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1057 AM EST THU MAR 09 2017 VALID 12Z SUN MAR 12 2017 - 12Z THU MAR 16 2017 ...PATTERN OVERVIEW AND MODEL EVALUATION... A RIDGE OVER THE WEST/ADJACENT HIGH PLAINS AND TROUGH OVER THE EAST WILL BE THE MEAN SYNOPTIC PATTERN THROUGH THE EXTENDED PERIOD... BECOMING MORE AMPLIFIED MONDAY ONWARD WITH POTENTIAL MULTIPLE DIPS IN UPPER JETS AND POSSIBLE PHASING FOR A RETURN TO WINTER. WPC FAVORED A SOLID BLEND OF THE 00/06Z GFS/GEFS AND 00Z ECMWF/EC MEAN THROUGHOUT MOST OF THE FORECAST PERIOD. ...WEATHER HIGHLIGHTS... TEMPERATURES ARE FORECAST TO REMAIN ABOVE AVERAGE ACROSS MUCH OF THE WEST AND BELOW OR WELL-BELOW AVERAGE IN THE EAST. FOR AREAS PRIMARILY WEST OF THE ROCKIES...THE 5 DAY MAXIMUM MEAN TEMPERATURE FORECAST SHOW AFTERNOON HIGHS OF +5 TO +15 DEGREES WITH THE HIGHEST ANOMALIES OVER THE CENTRAL/SOUTHERN GREAT BASIN AND EASTERN COLORADO. FROM THE DAKOTAS TO TEXAS AND AREAS EAST...THE 5 DAY MEAN TEMPERATURE FORECAST WILL RANGE FROM -5 TO -20 DEGREES. THE COOLEST AREAS WILL LIKELY BE THE MIDWEST AND OHIO VALLEY/CENTRAL APPALACHIANS. MULTIPLE WAVES OF PRECIPITATION IS EXPECTED FOR THE PACIFIC NORTHWEST FOR SEVERAL DAYS. COASTAL AREAS AND VALLEYS WILL HAVE RAIN, POSSIBLY HEAVY AT TIMES, AND SNOW FOR THE HIGHER ELEVATIONS OF THE NORTHERN CASCADES AND THE NORTHERN ROCKIES. MODERATE TO HEAVY RAINS WITH EMBEDDED THUNDERSTORMS IS EXPECTED ALONG THE CENTRAL/EASTERN GULF COAST AND THE SOUTHEAST...WITH A SLIGHT PROBABILITY OF SNOW ACROSS NORTH CAROLINA NEAR THE NORTHERN EXTENT OF THE PRECIP SHIELD. LIGHT TO MODERATE SNOW WILL BE POSSIBLE FOR THE EASTERN DAKOTAS/UPPER MIDWEST AS A SHORTWAVE TROUGH DIGS THROUGH THE CENTRAL U.S. ON SUNDAY... SPREADING ACROSS THE OHIO AND TENNESSEE VALLEYS/APPALACHIANS ON MONDAY. THE UPPER DYNAMICS WILL BEGIN TO TRANSFER TO THE MID-ATLANTIC COAST ON MONDAY FOR FRONTOGENESIS AND POSSIBLE BURST IN QPF. FOR TUESDAY AND BEYOND... A POSSIBLE AXIS OF SIGNIFICANT SNOWFALL WITH RAPID SURFACE CYCLOGENESIS WILL BE THE FOCUS FROM THE MID-ATLANTIC COAST TO NEW ENGLAND. OVERNIGHT BOTH THE OPERATIONAL GFS AND ECMWF SUGGESTED THE HEAVIEST AXIS ALONG OR JUST EAST OF THE I95 CORRIDOR FROM PHL/NYC TO BOS.... WHEREAS THE GUIDANCE FROM THIS MORNING SUGGESTED A SLIGHT SHIFT TO THE EAST. THE LATE WINTER STORM WILL SLOWLY DEPART NEW ENGLAND BY THE END OF THE PERIOD. A STRONG FRONTAL ZONE MOVES INTO THE NORTHER TIER OF THE COUNTRY FOR RAIN/MTN SNOW BY MIDWEEK. CAMPBELL