ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 151 PM EDT MON OCT 17 2016 VALID 12Z FRI OCT 21 2016 - 12Z TUE OCT 25 2016 MODELS SHOW ABOUT AVERAGE AGREEMENT IN ALLOWING THE NORTHERN STREAM TO MOVE SOUTHWARD FROM THE ARCTIC OCEAN TO OVER THE MAINLAND THROUGH THE END OF THE WEEK AND NEXT WEEKEND... SUPPORTING A COOLING TREND ALONG WITH MAINLY DRY CONDITIONS FOR THE MAINLAND. THE EXCEPTION IS THE 00Z ECMWF THAT PHASES WITH A SHORTWAVE TROUGH CLIPPING THE EASTERN BERING SEA...THUS CONTRIBUTING TO ANOTHER LOW OVER THE GULF OF ALASKA BY NEXT MONDAY. ALTHOUGH SOME SUPPORT IS PROVIDED BY THE 12Z CANADIAN...THE 12Z GFS AND 90 PERCENT OF THE ECMWF ENSEMBLE MEMBERS ARE WEAKER AND MORE PROGRESSIVE. THE SOUTHWARD MOVEMENT OF THIS TROUGH SHOULD EJECT PORTIONS OF THE RESIDUAL GULF OF ALASKA UPPER TROUGH...THUS HELPING TO SUPPORT CONTINUED WET CONDITIONS FOR THE SOUTHEAST. THE SPREAD OF SCENARIOS FOR THIS EJECTION BECOMES VERY HIGH BY DAY 6/SUN...SO HAVE LEANED TOWARD THE MODEL CONSENSUS WITH A GREATER EMPHASIS ON THE ENSEMBLE MEANS. BY EARLY NEXT WEEK...THE MODEL CONSENSUS IS FOR A DEEPENING CYCLONE TO DEVELOP OVER THE BERING SEA...WITH THE 00Z ECMWF MOST REPRESENTATIVE OF THIS SCENARIO. HOWEVER...THE PROBABILITIES OF POSITION/TIMING/INTENSITY ARE LESS THAN 20 PERCENT AT THIS TIME. JAMES