EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 259 AM EDT WED OCT 19 2016 VALID 12Z SAT OCT 22 2016 - 12Z WED OCT 26 2016 ...OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT... GUIDANCE STILL DEVELOPS AN AMPLIFIED MEDIUM RANGE ERN PAC TROUGH/W-CENTRAL US RIDGE/EAST COAST TROUGH PATTERN. WITHIN THIS MEAN FLOW PRIMARY UNCERTAINTIES INVOLVE A STRONG NERN US SYSTEM/POSSIBLE INTERACTION WITH A WRN ATLANTIC DISTURBANCE NHC IS MONITORING FOR DEVELOPMENT...ENERGY ROUNDING THE W-CENTRAL US RIDGE...AND ERN PACIFIC TROUGH DETAILS. MODEL AND ENSEMBLE FORECAST SPREAD/UNCERTAINTY IS NEAR TO BELOW NORMAL AND A COMPOSITE WPC SOLUTION FOCUSES ON THE COMPATABLE 18 UTC GEFS MEAN AND 12 UTC ECMWF ENSEMBLE MEAN ALONG WITH SOME INPUT FROM THE GFS/ECMWF AND WPC CONTINUITY TO ADD SOME ADDITIONAL DETAIL. ...WEATHER HIGHLIGHTS/THREATS... A WET AND WINDY DEEP SYSTEM WILL BATTER THE NORTHEAST INTO THE WEEKEND AND LOW PRESSURE LINGERING OVER ERN CANADA KEEPS WINDS BRISK SIDE INTO EARLY NEXT WEEK. MOISTURE ASSOCIATED WITH THE POTENTIAL WRN ATLANTIC SYSTEM BEING MONITORED BY NHC MAY ENHANCE RAINFALL AMOUNTS OVER NEW ENGLAND WITH MAINE BEING THE MOST LIKELY FOCUS FOR HIGHEST TOTALS. THERE MAY BE ENOUGH COLD AIR BEHIND THE SYSTEM TO SUPPORT SOME HIGHER ELEVATION SNOWS OVER NEW ENGLAND BUT A WIDESPREAD HEAVY SNOW THREAT WILL FOCUS OVER QUEBEC PROVINCE. ANOTHER REGION OF HEAVY PCPN WILL FOCUS UPON THE CENTRAL-NRN WEST COAST AS MULTIPLE SYSTEMS ROTATE WITHIN/AROUND THE OFFSHORE MEAN TROUGH ALOFT. PERIODIC LOCAL/TERRAIN ENHANCED ACTIVITY WILL OFFER LESS COVERAGE/INTENSITY LESS EXTREME THAN THE RECENT SERIES OF SYSTEMS. EJECTING IMPULSES RUNNING INLAND OVERTOP THE RIDGE WILL SUPPORT MUCH MORE MODEST PCPN INTO THE N-CENTRAL INTERMOUNTAIN W/ROCKIES. EXPECT FAIRLY SLOW EVOLUTION OF THE FORECAST TROUGH/RIDGE/TROUGH PATTERN ALOFT TO YIELD NEAR TO BELOW NORMAL TEMPS ALONG THE WEST COAST AND OVER THE ERN STATES WHILE ABOVE NORMAL READINGS PREVAIL FROM THE INTERIOR WEST THROUGH THE PLAINS. LOCATIONS FROM THE GREAT BASIN INTO THE PLAINS MAY SEE MULTIPLE DAYS WITH PLUS 10-15F OR GREATER ANOMALIES FOR MIN AND/OR MAX TEMPS. SCHICHTEL