ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1234 PM EDT THU SEP 10 2015 VALID 12Z MON SEP 14 2015 - 12Z FRI SEP 18 2015 THE BEST ARGUMENT FOR A CONTINUATION OF AN ENSEMBLE APPROACH ACROSS THE ALASKA REGION AT THE MEDIUM RANGE IS TO PLACE THE MOST RECENT OPERATIONAL SURFACE FORECASTS VALID AT 00Z THURSDAY SEPTEMBER 17 ON THE SAME SCREEN. THE 00Z ECMWF HAS A DEEP LOW CROSSING THE ANADYR GULF AND ANOTHER ENERGETIC WAVE PACKET DRAWING NORTHWARD TOWARD THE ALEUTIANS--PART JIMENA REMNANT/PART VORTEX ORIGINATING OVER THE SEA OF OKHOTSK. THE 00Z CANADIAN HAS A VERY DEEP--AND GETTING DEEPER--LOW CENTERED OVER THE OUTER ALEUTIANS. THE 06Z GFS HAS A FLAT WAVE COMING INTO THE WEST COAST OF ALASKA AND A DEEP CYCLONE DIVING TOWARD VANCOUVER. MUCH OF THE VARIABILITY OWES TO WHETHER OR NOT TROPICAL ENERGY AND MOISTURE GET INCORPORATED INTO THE POLAR WESTERLIES--AN INTERACTION THE ENSEMBLE MEANS HAVE SUCCESSFULLY PLAYED DOWN RECENTLY (KILO, MOST NOTABLY). THERE IS ENOUGH CYCLONIC GRADIENT IN THE MEANS FROM THE BERING TO WESTERN ALASKA TO THE GULF AND PANHANDLE TO KEEP THE SENSIBLE WEATHER IN THE GRIDS "UNSETTLED," WHILE AVOIDING THE FLIP-FLOPPING THAT "SURFING" ANY GIVEN OPERATIONAL RUN WOULD AFFORD. CISCO