ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 313 PM EDT THU AUG 04 2016 VALID 12Z MON AUG 08 2016 - 12Z FRI AUG 12 2016 DURING THE FIRST HALF OF THE PERIOD GUIDANCE HAS COME INTO BETTER AGREEMENT FOR DETAILS OVER/NEAR THE MAINLAND AS AN UPR LOW WOBBLES OVER THE EXTREME WRN/SWRN MAINLAND AND NRN PACIFIC ENERGY TO THE S CONTINUES EWD/NEWD. ASIDE FROM MINOR DETAILS AND TIMING DIFFS THAT DEVELOP DUE TO UPSTREAM ISSUES... THIS PART OF THE FCST HAS GOOD CONTINUITY AS PREVIOUSLY LESS FAVORED GFS/GEFS RUNS HAVE TRENDED NWD TO PRIOR CONSENSUS WITH THE LATITUDE OF THE UPR LOW. EVOLUTION JUST W OF KAMCHATKA DURING THE FIRST HALF OF NEXT WEEK APPEARS QUITE SENSITIVE AND WILL DETERMINE THE FCST ACROSS THE BERING SEA TOWARD THE MAINLAND. AROUND THAT TIME THERE MAY BE A SPLIT IN ENERGY EMERGING FROM ERN ASIA. SOLNS LIKE THE 00Z-06Z GFS/00Z ECMWF PROGRESS THE GREATER PART OF MID LVL SUPPORT EWD AND THUS BRING A WELL DEFINED SFC LOW ACROSS THE BERING SEA. THIS REFLECTS A TREND TOWARD EARLIER ECMWF RUNS THAT SHOWED A SIMILAR WAVE. SOME OTHER GUIDANCE INCLUDING MOST RECENTLY THE 12Z GFS PULL SOMEWHAT MORE ENERGY SWD INTO THE WRN PAC TROPICAL CYCLONE OMAIS... RESULTING IN A WEAKER/MORE NWD SFC FEATURE ACROSS THE BERING SEA. THE ECMWF ENSEMBLE MEAN HINTS AT THIS WAVE FOR A WHILE BEFORE WASHING IT OUT WHILE GEFS MEANS HAVE YET TO DEPICT IT. FOR NOW PREFER SOMEWHAT BETTER DEFINITION THAN CONTINUITY OR THE GEFS MEANS BUT UNCERTAINTY RECOMMENDS A WEAKER WAVE THAN FCST BY THE AFOREMENTIONED 00Z/06Z MODEL CLUSTER. WHAT ENERGY CROSSES THE BERING SEA MAY SETTLE INTO THE MEAN TROUGH POSN NEAR 160W... EJECTING THE INITIAL UPR LOW IN THE PROCESS. WHILE THERE HAS ALWAYS BEEN A STRAY SOLN OR TWO... MODELS/MEANS AS A WHOLE HAVE BEEN SHOWING BETTER THAN AVG AGREEMENT/CONTINUITY WITH OMAIS AND EVENTUAL EXTRATROPICAL EVOLUTION TRACKING INTO THE BERING SEA DURING THE LATTER HALF OF THE PERIOD. AS HAS BEEN THE CASE THE PAST DAY OR SO THE ECMWF MEAN LEANS TOWARD THE FASTER SIDE OF THE SPREAD. THERE IS STILL A DEPENDENCE ON NRN STREAM FLOW DETAILS THAT COULD RESULT IN A PERIOD OF GREATER SPREAD AT SOME POINT AND SOME DOWNSTREAM EFFECTS REMAIN UNCERTAIN. ACROSS HIGHER LATITUDES THE ONE ITEM OF NOTE IS THAT THE 12Z GFS IS MUCH FASTER THAN MODEL/ENSEMBLE CONSENSUS WITH A SHRTWV CROSSING SIBERIA AND CONTINUING ACROSS THE NRN MAINLAND. FOR DAYS 4-5 MON-TUE A BLEND OF HALF 00Z ECMWF AND HALF 00Z-06Z GFS REPRESENTS CONSENSUS WELL. PARTIAL INCLUSION OF THE 06Z GEFS/00Z ECMWF MEANS HELPS TO WEAKEN THE UNCERTAIN WAVE ACROSS THE BERING SEA GOING INTO DAYS 6-7 WED-THU AND SMOOTH OUT LOWER CONFIDENCE SHRTWV DETAILS NEAR THE MAINLAND. BY THE END OF THE PERIOD A COMPROMISE AMONG THE 06Z GFS/GEFS MEAN AND 00Z ECMWF/ECMWF MEAN PROVIDES A GOOD STARTING POINT OVERALL... WITH TIMING OF OMAIS THAT IS SLOWER THAN THE ECMWF MEAN INTERMEDIATE SOLN FOR DETAILS OF THE WRN MAINLAND MEAN TROUGH. RAUSCH