ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 229 PM EDT FRI AUG 12 2016 VALID 12Z TUE AUG 16 2016 - 12Z SAT AUG 20 2016 THE 12/00Z ECENS/GEFS MEANS AND THEIR DETERMINISTIC RUNS HAVE RESOLVED MANY OF THE SHORTWAVE DETAILS AND CONCERNS IN THE BERING SEA BETWEEN 16/12Z AND 18/12Z. AND WERE USED EXTENSIVELY FOR THE MASS FIELD GRAPHICS AND GRID FILES. THE SOLUTION SPREAD --- ONCE CONFINED TO THE SOUTHEAST BERING SEA ALOFT --- HAS SHIFTED INTO THE NORTHWEST AND WESTERN GULF OF ALASKA ---ALONG THE NORTHERN PERIPHERY OF A BUILDING DEEP-LAYERED RIDGE IN THE EAST CENTRAL PACIFIC. NOW THAT THE GFS/ECMWF AGREE ON THE NUMBER OF NW-TO-SE MOVING SHORTWAVES IN THE BERING SEA --- THE CHALLENGE IS WITH THE SPACING BETWEEN THESE MID-LEVEL SYSTEMS AS THEY ARC (ROTATE COUNTER-CLOCKWISE) ACROSS THE ALEUTIANS AND INTO THE WESTERN GULF OF ALASKA. CONSEQUENTLY, THE LARGEST SPREAD ALOFT SHIFTS FROM 170W ON DAY 7 TO 140W ON DAY 8. OVERALL, THE FLOW PATTERN ALOFT DOES SEEM STRAIGHT-FORWARD WITH THE RIDGE AXIS ALONG 135W-140W GRADUALLY 'FLATTENING' AS THE SERIES OF WEST-SOUTHWEST TO EAST-NORTHEAST MOVING SHORTWAVES MIGRATES ACROSS THE GULF OF ALASKA AND INTO THE ALASKA PANHANDLE. TIMING THESE BERING SEA SHORTWAVES INTO WEST CENTRAL CANADA --- IS THE PRIMARY REASON TO CARRY A 65/35 RATIO OF ECENS-TO-GEFS MEAN FOR DAY 7-8. AND WHAT MAKES THE DOWNSTREAM FLOW PATTERN OVER THE GULF 'SIMPLER' --- IS THE FACT THAT A STRONG RIDGE BUILDING POLEWARD ALONG 170E NOW LIMITS THE EASTWARD PROPAGATION OF 'CONSON' AND ALLOWS THE BERING SEA AND NORTHEAST SIBERIA A DIRECT ROUTE TO THE GULF. THE GEFS/ECENS MEANS AND TELECONNECTION TOOLS (D+8s) LOOKED TO BE IN SOLID AGREEMENT ACROSS THE NORTH PACIFIC BASIN. VOJTESAK