ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 341 PM EDT MON AUG 01 2016 VALID 12Z FRI AUG 05 2016 - 12Z TUE AUG 09 2016 ...GUIDANCE/UNCERTAINTY ASSESSMENT... THE WPC ALASKAN MEDIUM RANGE PRODUCT SUITE MAINTAINS CLOSE WPC CONTINUITY AS PRIMARILY DERIVED FROM A COMPOSITE BLEND OF REASONABLY WELL CLUSTERED GUDIANCE FROM THE 12 UTC GFS/00 UTC ECMWF AND 00 UTC NAEFS/ECMWF ENSEMBLE MEANS DAYS 4/FRI IN A PERIOD WITH GOOD PREDICTABILITY. SPREAD THEN INCREASES RAPIDLY SO OPT FOR JUST A BLEND OF THESE STILL COMPATABLE ENSEMBLE MEANS THEN AMID GROWING UNCERTAINTY...WITH GREATER WEIGHTING APPLIED TO ECMWF ENSEMBLES THAT SEEM TO CLUSTER BETTER WITH RECENT MODEL TRENDS AND WPC CONTINUITY. ...PATTERN AND WEATHER HIGHLIGHTS/THREATS... SHORT RANGE MID-UPPER LEVEL TROUGH PASSAGE OVER THE ARCTIC LAYS A SURFACE FRONT DOWN ACROSS THE INTERIOR...WITH ADDITIONAL DIGGING ENERGIES UNDERNEATH FORMING A CLOSED LOW BACK OVER THE NRN BERING SEA. THIS SUPPORTS AN ORGANIZED AND LINGERING SURFACE LOW/PCPN THREAT FROM THE BERING SEA TO WRN AK...INLAND INTO THE INTERIOR AND WINDWARD NRN MOUNTAIN TERRAIN OVER THE NEXT WEEK. MOISTURE AND SUPPORT ALOFT COULD FUEL SOME HEAVIER AMOUNTS...ESPECIALLY OVER WRN AK. GUIDANCE MEANWHILE ALSO SHOWS SIGNALS FOR APPROACH TO THE SRN BERING SEA/ALEUTIANS THEN SW/WRN/SRN AK OF NERN ASIAN ENERGY TO FAVOR A POTENTIALLY DEEPER SURFACE SYSTEM WITH AN ASSOCIATED MOISTURE AND ORGANIZED RAIN FOCUS BY NEXT WEEKEND INTO EARLY NEXT WEEK. THIS LOW HAS LESS PREDICTABILTY...BUT THE MANUALLY ADJUSTED WPC PROGS MAINTAINED FEATURE CONTINUITY DESPITE GUIDANCE THAT ALBEIT HAS BEEN MORE VARIED OVER THE PAST COUPLE OF DAYS. SCHICHTEL