EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 236 AM EDT SAT NOV 01 2014 VALID 12Z TUE NOV 04 2014 - 12Z SAT NOV 08 2014 ...OVERVIEW... FROM THE MULTI-DAY MEAN PERSPECTIVE MOST GUIDANCE IS SHOWING A RIDGE NEAR OR JUST INLAND FROM THE WEST COAST AND TROUGHING DOWNSTREAM OVER THE ERN HALF OF THE CONUS. HOWEVER AS WAS THE CASE YDAY THERE ARE SOME SIGNIFICANT INTERMEDIATE-SCALE ISSUES THAT LOWER CONFIDENCE IN FCST SPECIFICS. SPECIFICALLY THESE ARE TIMING OF ERN PAC TROUGH ENERGY EXPECTED TO REACH THE WEST COAST LATE IN THE WEEK AND RESULTING TIMING/AMPLITUDE OF THE ERN TROUGH... ALONG WITH SRN STREAM FLOW THAT MAY CLOSE OFF AN UPR LOW OVER NWRN MEXICO OR ELSE BE MORE PROGRESSIVE/SHEARED. ...GUIDANCE EVALUATION/PREFERENCES... FROM EARLY IN THE PERIOD THERE IS STILL CONSIDERABLE MODEL/ENSEMBLE SPREAD REGARDING HOW INITIAL SRN ROCKIES/NWRN MEXICO ENERGY EVOLVES OVER THE COURSE OF THE PERIOD. VERSUS PRIOR RUNS... THE PAST TWO RUNS OF THE ECMWF MEAN REFLECT MOST OPERATIONAL ECMWF/UKMET RUNS THAT HAVE BEEN DEPOSITING A CLOSED LOW OVER NWRN MEXICO. GFS AND SOME GEFS MEAN RUNS HAVE TENDED TO BE RATHER PROGRESSIVE... THOUGH IT IS NOTED THAT THE NEW 00Z RUN HAS ADJUSTED SLOWER AND 18Z/00Z PARALLEL GFS RUNS LEAN MORE TOWARD LEAVING BEHIND AT LEAST SOME ENERGY OVER NWRN MEXICO. THUS WOULD PREFER TO INCORPORATE SOMEWHAT MORE OF THE SLOWER/CLOSED SCENARIO FOR THIS ENERGY. NRN STREAM TIMING ISSUES ORIGINATE OVER THE PACIFIC ALREADY NEAR THE START OF THE PERIOD WITH RESULTING ERN CONUS DIFFS BECOMING APPARENT BY DAYS 4-5 WED-THU. IN GENERAL THE 12Z ECMWF AND TO A SLIGHTLY LESSER EXTENT ECMWF MEAN ARE ON THE FASTER SIDE OF THE FULL GUIDANCE SPREAD WITH BOTH THE ERN PAC SHRTWV HEADING INTO THE MEAN RIDGE AS WELL AS THE AMPLIFYING ERN TROUGH THAT SHOULD SUPPORT WHAT COULD BE A FAIRLY VIGOROUS SFC SYSTEM AFFECTING THE NERN STATES BY LATE IN THE WEEK. REMAINING SOLNS HAVE BEEN QUITE DIVERSE WITH ERN PAC SHRTWV TIMING IN PARTICULAR. GIVEN ESTABLISHED WPC CONTINUITY LATEST PREFS WERE TO EMPHASIZE NEARLY EVEN WEIGHTING OF THE 12Z ECMWF MEAN AND THE SLIGHTLY SLOWER 18Z PARALLEL GFS... WITH THE LATTER ALSO INCLUDED TO DEEPEN THE NERN SYSTEM SOMEWHAT AS RECOMMENDED BY SOME OPERATIONAL MODEL RUNS. NOTE THAT THE NEW 00Z GFS/GEFS/UKMET/CMC RUNS DISPLAY MORE PRONOUNCED CLUSTERING TOWARD SLOWER TIMING THAN THE 12Z ECMWF/ECMWF MEAN. THE 00Z ECMWF THROUGH WED HAS ADJUSTED SLOWER BUT IS STILL A LITTLE FASTER THAN THE GFS CLUSTER. BASED ON GUIDANCE THROUGH THE 18Z CYCLE... COMBINED PREFS FOR NRN AND SRN STREAM FEATURES LED TO THE USE OF A 40/40/20 BLEND OF THE 18Z PARALLEL GFS/12Z ECMWF MEAN/12Z NAEFS MEAN THROUGH DAY 5 THU... TRENDING TOWARD A BLEND OF 12Z ECMWF MEAN/18Z GEFS MEAN/12Z NAEFS MEAN BY DAY 7 SAT GIVEN REDUCED CONFIDENCE IN ANY OPERATIONAL MODEL DETAILS. ...SENSIBLE WEATHER HIGHLIGHTS... LOCATIONS FROM THE RIO GRANDE VLY INTO THE LOWER OH VLY HAVE THE BEST POTENTIAL FOR AREAS OF HVY RNFL... WITH A WAVY FRONTAL BOUNDARY INTERACTING WITH LOW LVL GULF INFLOW AND ADDED INPUT OF MSTR FROM ERN PAC T.S. VANCE. ONGOING QUESTION MARKS WITH UPR LVL FLOW INITIALLY OVER THE SRN ROCKIES/NWRN MEXICO LEAD TO LOWER THAN DESIRED CONFIDENCE ON COVERAGE/DURATION OF HEAVIEST ACTIVITY. IN ADDITION BY LATE IN THE PERIOD NRN STREAM INTERACTION COULD DRAW SOME OF THIS MSTR NWD/NEWD BUT SOLNS ARE QUITE VARIED IN THIS REGARD. MEANWHILE THE PAC NW/EXTREME NRN ROCKIES SHOULD SEE ONE OR MORE EPISODES OF PCPN ENHANCED OVER FAVORED TERRAIN... AND THE SYSTEM EXPECTED TO AFFECT THE NORTHEAST LATE IN THE WEEK MAY BE ACCOMPANIED BY ORGANIZED PCPN INCLUDING SOME SNOW ON THE WRN PERIPHERY ASSUMING SUFFICIENTLY STRONG DEVELOPMENT. THE OVERALL PATTERN SHOULD SUPPORT ABOVE NORMAL TEMPS ON MOST DAYS OVER THE WEST AND INTO PARTS OF THE NRN/CNTRL PLAINS. OVER THE EAST NEAR TO SLIGHTLY ABOVE NORMAL READINGS SHOULD TREND BELOW NORMAL BY FRI-SAT BUT WITH MOST ANOMALIES REMAINING WITHIN 10F OF NORMAL. RAUSCH