EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 130 AM EST FRI DEC 25 2015 VALID 12Z MON DEC 28 2015 - 12Z FRI JAN 01 2016 ...OVERVIEW... THE MAJORITY OF ACTIVE WEATHER THIS PERIOD SHOULD BE OVER THE ERN HALF OF THE LOWER 48 AHEAD OF A WRN-CNTRL CONUS MEAN TROUGH THAT SHOULD EVENTUALLY DRIFT TOWARD THE EAST AS UPR RIDGING BUILDS OVER WRN CANADA AND THE WEST COAST. THE PRIMARY FOCUS EARLY IN THE PERIOD WILL BE WITH A STORM LIFTING NEWD FROM THE SRN PLAINS... ACCOMPANIED BY STRONG WINDS AND AREAS OF WARM SECTOR HVY RNFL/COLD SECTOR WINTRY PCPN. TRAILING ENERGY ALOFT SHOULD BRING ANOTHER AREA OF MSTR INTO PARTS OF THE EAST MID-LATE WEEK. ...GUIDANCE EVALUATION/PREFERENCES... DAYS 3-4 MON-TUE WERE BASED PRIMARILY ON THE 12Z ECMWF/18Z GFS WITH A MORE EVEN MODEL/ENSEMBLE MEAN BLEND EMPLOYED FOR DAY 5 WED. THOSE MODEL RUNS AND THEIR ENSEMBLE MEANS SHOWED DECENT CLUSTERING FOR THE SYSTEM THAT SHOULD GRADUALLY WEAKEN AS IT TRACKS FROM THE SRN PLAINS INTO THE GRTLKS AS WELL AS FOR THE WAVE BEGINNING TO DEVELOP NEAR THE EAST COAST AND THEN TRACKING INTO THE ATLC. MEANWHILE GUIDANCE IS SOMEWHAT MIXED REGARDING THE STRENGTH OF THE UPR TROUGH MOVING ACROSS THE WEST... WITH RECENT ECMWF/ECMWF MEAN RUNS SHOWING A STRONGER TROUGH THAN MOST OTHER SOLNS. CONTINUITY AND TRENDS GENERALLY FAVOR LEANING A BIT TOWARD THE ECMWF SCENARIO FOR FEATURES OF INTEREST THOUGH WITHOUT ENOUGH CONFIDENCE TO GO BEYOND 60 PCT WEIGHTING. AFTER THE DAY 5 TRANSITION... DAYS 6-7 THU-FRI START WITH THE 18Z GEFS/12Z ECMWF MEANS EXCLUSIVELY. THE PRIMARY UNCERTAINTY BY THE LATTER HALF OF THE WEEK APPEARS TO BE THE EXTENT TO WHICH UPR TROUGH ENERGY HANGS BACK OVER THE WEST AND RESULTING IMPACT ON UPR TROUGH AMPLITUDE/TIMING OVER THE EAST. ENSEMBLE SPAGHETTI PLOTS SHOW CONSIDERABLE SPREAD SO CONFIDENCE IN A SPECIFIC SOLN DECREASES BY THIS TIME FRAME. AT THE MOMENT THE ENSEMBLE MEANS HAVE THE BEST INTERMEDIATE IDEA AMONG THE FULL RANGE OF SOLNS. TELECONNECTIONS RELATIVE TO THE CORE OF POSITIVE HGT ANOMALIES FCST TO REACH WRN CANADA IN D+8 CHARTS DO NOT SUPPORT NEARLY AS MUCH LINGERING WRN CONUS ENERGY AS DEPICTED IN RECENT CMC RUNS WHILE A FIRM CONSENSUS OF GUIDANCE HOLDS BACK ON ERN CONUS TROUGH AMPLITUDE RELATIVE TO GFS RUNS LATE IN THE PERIOD. ...SENSIBLE WEATHER HIGHLIGHTS... EARLY WEEK STORM TRACKING NEWD FROM THE SRN PLAINS AND WAVE TRACKING NEAR/OFFSHORE THE EAST COAST WILL SPREAD A BROAD AREA OF PCPN ACROSS THE ERN HALF OF THE CONUS. BEST POTENTIAL FOR WINTRY PCPN SHOULD BE FROM THE S-CNTRL PLAINS INTO THE GRTLKS/NORTHEAST WHILE AREAS FARTHER SWD MAY SEE LOCALLY HVY RNFL. WINDS WITH THIS SYSTEM WILL BE ENHANCED BY A STRONG SFC HIGH TRACKING ACROSS SRN CANADA/NEW ENGLAND. WITH LESSER CONFIDENCE IN TIMING/COVERAGE... EXPECT ANOTHER AREA OF MSTR TO EXTEND NEWD FROM THE GULF OF MEXICO MID-LATE WEEK. FRONTAL WAVINESS/PSBL TRAINING MAY LEAD TO LOCALLY HVY RNFL OVER THE SOUTHEAST WITH PREFERRED SOLNS SFC/ALOFT INDICATING A SLOWER DEPARTURE OF PCPN VERSUS LATEST GFS RUNS. ENERGY MOVING INTO/THROUGH THE WEST SHOULD NOT HAVE MUCH MSTR TO WORK WITH. WHAT PCPN OCCURS SHOULD PRIMARILY BE FROM THE CNTRL-NRN WEST COAST INTO THE ROCKIES WITH A DRYING TREND AS UPR RIDGING BUILDS IN. VERY WARM TEMPS SHOULD PERSIST OVER THE SOUTHEAST INTO MIDWEEK WITH SOME EARLY WEEK ANOMALIES UP TO PLUS 20-35F FOR MINS AND PLUS 15-20F FOR HIGHS. ON THE OTHER HAND TEMPS SHOULD BE BELOW NORMAL OVER THE WRN-CNTRL STATES ASIDE FROM MORE MODERATE READINGS NEAR THE WEST COAST AND IN THE NRN PLAINS. THE MOST EXTREME READINGS OF 15-25F BELOW NORMAL ARE MOST LIKELY OVER/NEAR THE SRN HIGH PLAINS. OTHER AREAS SHOULD SEE ONE OR MORE DAYS AT 5-15F BELOW NORMAL. RAUSCH