EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1054 AM EST MON NOV 30 2015 VALID 12Z THU DEC 03 2015 - 12Z MON DEC 07 2015 ...OVERVIEW... WITHIN A FAIRLY PROGRESSIVE PATTERN GUIDANCE SHOWS BETTER THAN AVG AGREEMENT FOR MOST LARGER SCALE FEATURES ALBEIT WITH SOME DETAILS UP FOR DEBATE. PRIMARY QUESTION MARKS INVOLVE THE DEGREE OF SEPARATION WITHIN A LEADING SHRTWV REACHING THE WEST LATE THIS WEEK AND THE NEXT SYSTEM ARRIVING TOWARD THE END OF THE PERIOD SUN-MON... THOUGH UNCERTAINTIES LINGER FOR SHRTWV ENERGY CROSSING THE EAST THU-SAT AS WELL. ...GUIDANCE EVALUATION/PREFERENCES... AT THE START OF THE PERIOD THU ONE SYSTEM WILL BE LEAVING NEW ENGLAND WHILE ANOTHER WILL BE ARRIVING ALONG THE WEST COAST. RECENT TRENDS FOR THE NERN SYSTEM HAVE BEEN SLOWER BUT APPROACHING SHRTWV ENERGY MAY RESULT IN SLIGHTLY FASTER TIMING THAN THE 00Z ECMWF AFTER THU. NO PRONOUNCED TRENDS ARE EVIDENT FOR THE WEST COAST SYSTEM THOUGH THE CURRENT SOLN ENVELOPE SUGGESTS A FARTHER NWD SFC TRACK THAN SHOWN BY THE 06Z GFS. FOR UPDATED PREFS THROUGH THU BASED ON NEW 12Z GUIDANCE... CONSULT THE MODEL DIAGNOSTIC DISCUSSION PMDHMD. MODEL/ENSEMBLE SOLNS HAVE VARIED FOR DETAILS OF SHRTWV ENERGY CROSSING ERN NOAM EARLY-MID PERIOD WITH LITTLE IN THE WAY OF DISCERNIBLE TRENDS SO FAR. EVOLUTION OF ENERGY CROSSING THE SOUTHEAST WILL INFLUENCE WAVINESS ALONG A FRONT CROSSING THE FL PENINSULA EARLY IN THE PERIOD. CONFIDENCE IN SPECIFICS OF ANY PARTICULAR OPERATIONAL MODEL RUN IS FAIRLY LOW SO A GENERAL BLEND/ENSMEAN APPROACH SEEMS BEST HERE. FOR THE TROUGH HEADING INTO THE WEST LATE THIS WEEK THERE IS DECENT OPERATIONAL MODEL AGREEMENT THAT FLOW SHOULD SEPARATE ENOUGH TO RESULT IN A CLOSED CIRC CROSSING OVER/NEAR THE FOUR CORNERS REGION AROUND DAY 5 SAT AND THEN CONTINUING INTO THE PLAINS. THE MEANS HINT AT THIS SCENARIO BUT DO NOT YET CLOSE OFF AN UPR LOW AND THUS ARE FASTER WITH THE TROUGH. OVERALL PROGRESSIVE NATURE OF THE MEAN PATTERN MIGHT ARGUE AGAINST THE SLOWEST SIDE OF THE SPREAD AS REPRESENTED BY THE 00Z CMC BUT AT LEAST HALF WEIGHTING OF REMAINING OPERATIONAL SOLNS SEEMS REASONABLE. SOLNS ARE MORE DIVERSE WITH THE NEXT TROUGH ARRIVING INTO THE WEST. SO FAR ECMWF RUNS HAVE TENDED TO BE MORE EAGER TO SEPARATE FLOW WITHIN THE TROUGH VERSUS THE GFS WHILE ENSMEANS MAINTAIN A MERE OPEN WAVE. CURRENTLY PREFER A GENERAL MODEL/ENSMEAN BLEND WHILE AWAITING IMPROVED CLUSTERING. DAY 3 THU EMPHASIZES THE 00Z GFS/ECMWF GIVEN PREFS FOR OPERATIONAL MODEL DETAIL AND THOSE SOLNS COMPARING WELL TO THE ENSEMBLE SPREAD. AFTER THAT TIME THE FCST INCORPORATES NEARLY EVEN WEIGHTING OF THOSE MODEL RUNS AND THE 06Z GEFS/00Z ECMWF MEANS TO BALANCE SLIGHTLY DIFFERING PREFS TOWARD EITHER MODEL OR ENSEMBLE SOLNS DEPENDING ON THE SYSTEM. THIS BLEND YIELDS GOOD CONTINUITY ASIDE FROM TYPICAL RUN TO RUN DETAIL DIFFS/MODEST TIMING TRENDS. ...SENSIBLE WEATHER HIGHLIGHTS... HEAVIEST PCPN DURING THE PERIOD SHOULD BE OVER THE CNTRL-NRN WEST COAST WITH THE SERIES OF SYSTEMS CROSSING THAT REGION AS WELL AS PORTIONS OF FLORIDA IN ASSOC WITH A WAVY FRONT PUSHING THROUGH AND S OF THE STATE. EXPECT THE LEADING PACIFIC TROUGH/PSBL EMBEDDED UPR LOW TO GENERATE FAIRLY MODEST INTERIOR WEST/ROCKIES SNOW AND THEN SCT RNFL OVER THE PLAINS... WITH AMTS LIKELY CONSTRAINED BY A LACK OF GULF INFLOW. NEW ENGLAND MAY SEE RAIN/SNOW LINGERING INTO THU WITH THE SYSTEM TRACKING AWAY FROM THE COAST AT THE START OF THE PERIOD. THE EXPECTED PATTERN SHOULD FAVOR ABOVE NORMAL TEMPS ACROSS THE NRN TIER AND SOMEWHAT BELOW NORMAL TEMPS OVER THE SOUTH. THE NRN PLAINS IN PARTICULAR SHOULD BE QUITE WARM WITH MIN/MAX TEMPS PSBLY AVERAGING 15-20F ABOVE NORMAL FOR THE FULL THU-MON PERIOD. RAUSCH