EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1059 AM EST WED NOV 23 2016 VALID 12Z SAT NOV 26 2016 - 12Z WED NOV 30 2016 ...PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT... AS THE MEAN PATTERN EVOLVES TOWARD AN AMPLIFIED CONUS TROUGH BTWN ERN PAC AND WRN ATLC RIDGES... LATEST GUIDANCE IS SHOWING BETTER AGREEMENT FOR INDIVIDUAL SYSTEMS THAN SEEN IN SOME PREVIOUS RUNS THOUGH TYPICAL DETAIL UNCERTAINTIES REMAIN. BETTER CLUSTERING NOW ALLOWS FOR A CONSENSUS BLEND AMONG THE 00Z ECMWF/ECMWF MEAN..00Z GFS..AND 06Z GFS/GEFS MEAN TO SERVE AS THE FCST STARTING POINT THROUGH DAY 7 WED. DAYS 3-5 SAT-MON LEAN MOSTLY TOWARD THE OPERATIONAL RUNS WITH A MORE EVEN OPERATIONAL/ENSEMBLE WEIGHTING THEREAFTER. FOR THE SYSTEM OFF THE NORTHEAST DURING THE WEEKEND... EWD TREND FROM YDAYS GFS RUNS YIELD BETTER LONGITUDE AGREEMENT IN CURRENT SOLNS THOUGH LATITUDE DIFFS REMAIN. AN INTERMEDIATE TRACK STILL PROVIDES THE MOST STABLE FCST FOR THIS FEATURE. REGARDING WRN ENERGY EMERGING INTO THE PLAINS AND ORGANIZING A SIGNIFICANT STORM FROM THE PLAINS INTO THE UPR MS VLY/UPR GRTLKS... THE 00Z UKMET/CMC ARE RUNNING AHEAD OF CONSENSUS WITH THE LEADING ENERGY THAT WILL LIKELY WRAP UP OVER THE NRN TIER BUT THE GFS/ECMWF AND THEIR MEANS ARE NOW MUCH MORE AGREEABLE. CONFIDENCE IS INCREASING WITH RESPECT TO THE CLOSING OF AN UPR LOW SO IT IS DESIRABLE TO INCLUDE AT LEAST HALF WEIGHTING OF THE OPERATIONAL RUNS THAT ARE DEEPER WITH THE ASSOC SFC LOW VERSUS THE ENSEMBLE MEANS. LATEST CONSENSUS IS A LITTLE SLOWER/NWWD VS CONTINUITY WITH THIS SYSTEM. THIS TREND IS ACCEPTED GIVEN THE INCREASINGLY AMPLIFIED NATURE OF THE MEAN FLOW OVER THE CONUS AND SOMEWHAT SLOW PROGRESSION OF DOWNSTREAM FEATURES. FOR THE NRN PAC SYSTEM HEADING TOWARD THE WEST COAST BY LATE TUE-WED RECENT GFS/GEFS TRENDS HAVE BEEN FASTER TOWARD ECMWF/ECMWF MEAN RUNS. CURRENT SOLNS ARE WELL WITHIN TYPICAL ERRORS AT THE DAYS 6-7 TIME FRAME SO AN AVG OF THE LATEST MODELS/MEANS LOOKS REASONABLE. AS WAS THE CASE YDAY... D+8 MULTI-DAY MEANS SHOW STRONGER POSITIVE HGT ANOMALIES JUST NE OF HUDSON BAY... FAVORING A CNTRL/E-CNTRL U.S. MEAN TROUGH... RELATIVE TO ANOTHER CORE OF POSITIVE HGT ANOMALIES NEAR 150W WHICH ON ITS OWN WOULD FAVOR MORE WRN U.S. TROUGHING. AS SUGGESTED BY THE GREATER WRN TROUGHING IN THE CMC/CMC MEAN LATE IN THE PERIOD AND DIFFS THAT ARISE IN OTHER SOLNS JUST AFTER THE MEDIUM RANGE PERIOD... THERE IS STILL SOME UNCERTAINTY IN THE RELATIVE INFLUENCE OF THE TWO AREAS OF RIDGING/POSITIVE HGT ANOMALIES. ...WEATHER HIGHLIGHTS/THREATS... EXPECT SOME PCPN TO LINGER OVER THE NORTHEAST BEHIND DEPARTING LOW PRESSURE DURING THE WEEKEND. BEST POTENTIAL FOR WINTRY WEATHER WILL BE OVER INLAND/HIGHER ELEVATION LOCATIONS. SERIES OF SHRTWVS REACHING/CROSSING THE WEST WILL SUPPORT PERIODS OF ENHANCED RAIN/HIGHER ELEV SNOW DURING THE PERIOD. HIGHEST TOTALS ARE LIKELY TO EXTEND FROM THE PAC NW THROUGH THE NRN CA COAST AND SIERRA NEVADA RANGE. FAVORED TERRAIN FARTHER INLAND THROUGH THE ROCKIES SHOULD ALSO SEE PERIODS OF PCPN WITH SOME AREAS OF LOCALIZED ENHANCEMENT. WRN ENERGY HEADING INTO THE CENTRAL U.S. WILL ENCOURAGE CYCLOGENESIS/FRONTOGENESIS WITH AN EXPANDING AREA OF PCPN FROM THE CENTRAL-ERN PLAINS EWD DURING THE FIRST HALF OF NEXT WEEK. THERE ARE STILL SOME FINER DETAILS THAT ARE YET TO BE RESOLVED BUT BETTER GUIDANCE AGREEMENT IS GRADUALLY IMPROVING CONFIDENCE IN HVY RNFL POTENTIAL WITHIN AN AREA EXTENDING FROM THE MID-LWR MS VLY INTO THE OH VLY/TN VLY/SRN APLCHNS. SOME CONVECTION MAY BE STRONG AS WELL... WITH CURRENT SPC OUTLOOK HIGHLIGHTING LOCATIONS NEAR/INLAND FROM THE W-CNTRL GULF COAST. SOME OF THIS RNFL MAY EXTEND INTO DROUGHT AREAS OF THE SOUTHEAST MON-WED. MEANWHILE THE COLD SECTOR OVER THE NRN TIER MAY HAVE SOME HEAVY SNOW POTENTIAL ON THE NRN PERIPHERY OF THE PCPN SHIELD IN UPPER MIDWEST/GREAT LAKES WRAP-AROUND LOW FLOW. THERE MAY BE A PERIOD OF STRONG WINDS AS WELL DEPENDING ON SYSTEM STRENGTH. THE MOST ANOMALOUS TEMPS DURING THE PERIOD WILL BE AHEAD OF THE DEVELOPING PLAINS STORM WITH ONE OR MORE DAYS OF MAX AND/OR MIN READINGS AT LEAST 10-20F ABOVE NORMAL... BUT LIKELY NOT EXTREME ENOUGH TO REACH DAILY RECORD VALUES. PACIFIC ORIGIN OF FLOW SHOULD LEAD TO MORE MODEST NEGATIVE ANOMALIES BEHIND THE SYSTEM. RAUSCH