EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 145 AM EST TUE NOV 08 2016 VALID 12Z FRI NOV 11 2016 - 12Z TUE NOV 15 2016 ...OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT... BY THE LATTER HALF OF THE FCST PERIOD GUIDANCE CONTINUES TO SHOW SOME DEGREE OF CHANGE FROM THE INITIAL W-CNTRL NOAM RIDGE/EAST COAST TROUGH MEAN PATTERN. HOWEVER GUIDANCE SPREAD IS AT LEAST AS GREAT AS IT WAS 24 HRS AGO IN TERMS OF THE EXTENT TO WHICH THE PATTERN MAY RETROGRESS AND AMPLITUDE OF THE RIDGE/TROUGH. ECMWF/ECMWF MEAN RUNS HAVE BEEN VERY CONSISTENT SO FAR IN BUILDING A STRONG WEST COAST RIDGE EARLY NEXT WEEK WITH A DOWNSTREAM TROUGH AMPLIFYING OVER THE MS VALLEY. ON THE OTHER HAND LATEST GFS/GEFS RUNS AND TO SOME DEGREE CMC/CMC MEAN BRING MORE ERN PAC ENERGY INTO THE NWRN STATES THUS FLATTENING THE RIDGE AND DIVERTING THE MEAN TROUGH MORE TOWARD THE EAST COAST. TELECONNECTIONS RELATIVE TO THE PACIFIC MEAN TROUGH THAT IS FCST TO REMAIN FAIRLY STRONG AT LEAST INTO THE WEEKEND SUPPORT A DOWNSTREAM NOAM PATTERN CLOSEST TO THE GENERAL ECMWF/ECMWF MEAN SCENARIO. AT THE SAME TIME THERE IS SOME LEEWAY IN THE POSN OF THE ERN TROUGH AS RIDGING OVER THE E-CNTRL ATLC TELECONNECTS TO AN EAST COAST TROUGH... AND SOME LATEST D+8 MEANS SUGGEST THE PAC MEAN TROUGH MAY START WEAKENING. GIVEN THE PERSISTENCE OF THE CNTRL-ERN PAC PATTERN THROUGH MID-PERIOD... PREFER TO CONTINUE LEANING MORE IN THE ECMWF/ECMWF MEAN DIRECTION BUT WITH UNDERSTANDING OF THE OTHER FACTORS THAT COULD ULTIMATELY ALTER THE PATTERN. NEW 00Z GUIDANCE THUS FAR REMAINS MIXED WITH THE GFS/GEFS/CMC STILL BRINGING LOWER HGTS INTO THE NORTHWEST WHILE THE UKMET THROUGH 00Z MON LOOKS MUCH LIKE THE 12Z ECMWF/ECMWF MEAN. AS FOR DETAILS BEFORE THE LATE PERIOD UNCERTAINTY ARISES... FOR THE PAST COUPLE DAYS GUIDANCE HAS GENERALLY BEEN TRENDING TOWARD A MORE PROGRESSIVE AND OPEN TROUGH REACHING THE EAST COAST BY SAT. THERE ARE STILL SOME QUESTION MARKS OVER WHAT THE SWRN PERIPHERY OF THE TROUGH WILL DO. THE 18Z GFS WAS THE MOST EXTREME WITH ITS UPR LOW THAT CLOSES OFF AND CROSSES THE SC COAST ON SUN. THE NEW 00Z UKMET PULLS OFF A MUCH WEAKER BUNDLE OF ENERGY FARTHER WWD. SHRTWV ENERGY HEADING TOWARD THE PAC NW COAST ON FRI WILL PROGRESS RAPIDLY ACROSS THE NRN CONUS/SRN CANADA WITH TIME. THE AVG OF GUIDANCE HAS TRENDED FASTER WITH THIS SHRTWV AFTER PROGRESSING INLAND. THE 12Z GFS/ECMWF AND TO A LESSER EXTENT 18Z GEFS/12Z ECMWF MEANS REPRESENT THE BEST CONSENSUS FOR SIGNIFICANT FEATURES DAYS 3-4 FRI-SAT BEFORE PREFS TRANSITION TOWARD A MORE ECMWF MEAN/ECMWF VS GEFS MEAN SOLN BY DAYS 6-7 MON-TUE. ...WEATHER HIGHLIGHTS/THREATS... HEAVIEST PCPN FOR THE 5-DAY PERIOD IS MOST LIKELY TO BE OVER THE PAC NW AND IN PARTICULAR FAVORED TERRAIN OF WRN WA INTO VANCOUVER ISLAND. INCOMING SHRTWV ENERGY WILL SUPPORT ONE PERIOD OF RNFL FRI-SAT WITH ONE OR MORE IMPULSES LIKELY TO FOLLOW. MEANWHILE THERE MAY BE PERIODS OF ENHANCED RNFL NEAR THE SRN COAST OF TX IN THE VICINITY OF A PERSISTENT SFC TROUGH OFF THE WRN GULF COAST. SYSTEM CROSSING THE EAST FRI-SAT WILL BE ACCOMPANIED BY ONLY LGT PCPN IN THE GRTLKS/APLCHNS/NORTHEAST... SOME IN THE FORM OF SNOW. BY THE FIRST HALF OF NEXT WEEK EXPECT SOME INCREASE IN MSTR/RNFL OVER PARTS OF THE ERN HALF OF THE LOWER 48 AS MEAN TROUGHING ALOFT BEGINS TO EVOLVE OVER OR E OF THE MS VLY. HOWEVER GUIDANCE SPREAD REMAINS SUFFICIENT TO KEEP CONFIDENCE BELOW AVG FOR RESOLVING THE TIMING/COVERAGE/MAGNITUDE OF THIS MSTR INCREASE. MUCH OF THE WEST INTO THE NRN-CNTRL PLAINS SHOULD REMAIN QUITE WARM DURING THE PERIOD WITH MANY LOCATIONS SEEING HIGHS AT LEAST 10-20F ABOVE NORMAL. BEST POTENTIAL FOR PLUS 20F OR GREATER ANOMALIES ON ONE OR MORE DAYS WILL LIKELY BE OVER THE NRN PLAINS. EAST COAST STATES WILL SEE A BRIEF BURST OF CHILLY/BREEZY WEATHER WITH HIGHS UP TO ABOUT 10F BELOW NORMAL DURING THE WEEKEND FOLLOWED BY A REBOUND TO NEAR/SLIGHTLY ABOVE NORMAL TEMPS. RAUSCH