ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 157 PM EDT FRI JUN 06 2014 VALID 12Z TUE JUN 10 2014 - 12Z SAT JUN 14 2014 MOST GUIDANCE EXPECTS SOME DEGREE OF MEAN TROUGHING TO REMAIN OVER THE BERING SEA DURING THE PERIOD WITH A RIDGE OVER NWRN CANADA EXTENDING INTO PORTIONS OF THE MAINLAND. MULTI-DAY MEANS BY D+8 AGREE QUITE WELL UPON RIDGING OVER THE E-CNTRL PAC AND TELECONNECTIONS RELATIVE TO THIS FEATURE SUPPORT A SIMILAR PATTERN. OVER/NEAR THE MAINLAND THE PRIMARY UNCERTAINTIES ARE WITH HIGHER LATITUDE FLOW THAT MAY INTERACT WITH THE BERING SEA TROUGH AND WHETHER THE UPR LOW NEAR THE WRN COAST OF THE MAINLAND AS OF DAY 4 TUE WILL MEANDER FOR MULTIPLE DAYS OR BE EJECTED NEWD. LATEST ECMWF RUNS HAVE BEEN MOST AGGRESSIVE IN AMPLIFYING HIGH LATITUDE FLOW WITH THE RESULT IN THE 00Z VERSION BEING RATHER QUICK EJECTION OF THE UPR LOW ACROSS THE MAINLAND. RECENT GFS/CMC RUNS KEEP INTERACTION FROM HIGH LATITUDE FLOW MINIMAL AND THUS SHOW VERY LITTLE MOVEMENT OF THE UPR LOW. ECMWF ENSEMBLES HINT AT SOME INTERACTION BUT LESS THAN SEEN IN ECMWF RUNS. BY LATE IN THE FCST THE 06Z GEFS MEAN SHOWS SOME TRENDS IN THE ECMWF MEAN DIRECTION. AFTER TUE A NON-00Z ECMWF COMPROMISE... TRENDING TOWARD THE ENSEMBLE MEANS LATER IN THE FCST... APPEARS MOST REASONABLE AT THIS TIME ESPECIALLY WITH THE 12Z GFS OFFERING A COMPROMISE OF SORTS WITH NWD EJECTION OF THE UPR LOW LATE IN THE WEEK. TO THE S OF THIS MEAN TROUGH... EARLY IN THE PERIOD THERE IS DECENT CLUSTERING TOWARD WEAKENING/SHEARING OF A MODEST WRN ALEUTIANS SYSTEM AS IT BECOMES ABSORBED WITHIN THE MEAN TROUGH. SOME EARLIER MODEL RUNS HAD INDICATED GREATER EWD PROGRESSION. BEHIND THIS FEATURE THE PAST DAY OF GUIDANCE SHOWS A NOTICEABLE TREND TOWARD MORE W-CNTRL PAC TROUGHING ALOFT THAT MAY SUPPORT A SYSTEM AFFECTING THE ALEUTIANS BY LATE NEXT WEEK. RECENT ECMWF RUNS HAVE BEEN MORE CONSISTENT WITH THIS SYSTEM THAN THE GFS WITH A SLOWER TREND IN THE 00Z CMC BRINGING ITS TRACK CLOSER TO THE 00Z ECMWF THAT ITSELF IS A LITTLE FASTER THAN THE 06Z GEFS/00Z ECMWF MEANS. PREFER TO INTRODUCE THIS SYSTEM WITH A SOLN CLOSEST TO AN AVG OF THE 06Z GEFS/00Z ECMWF MEANS GIVEN CURRENT ENSEMBLE SPREAD AND THE DISTANT TIME FRAME. THE 12Z GFS HAS ADJUSTED TOWARD A SIMILAR TRACK LATE IN THE PERIOD. TODAYS BLEND INCORPORATES THE 00Z ECMWF MEAN AND 12Z/06Z GFS THROUGH DAY 6 THU... WITH THE 00Z ECMWF ALSO INCLUDED DAY 4 TUE BUT REPLACED BY THE 06Z GEFS MEAN THEREAFTER. DAYS 7-8 FRI-SAT START WITH AN EVEN WEIGHTING OF THE 06Z GEFS/00Z ECMWF MEANS WITH MODEST MANUAL ENHANCEMENT OF LOW PRESSURE FCST TO REACH THE ALEUTIANS NEXT SAT. RAUSCH