ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 111 PM EST THU NOV 30 2017 VALID 12Z MON DEC 04 2017 - 12Z FRI DEC 08 2017 ...STORMY WEATHER... ...GUIDANCE/UNCERTAINTY ASSESSMENT AND WEATHER THREATS... IT REMAINS THE CASE THAT LARGER SCALE ALASKAN FLOW IS WELL FORECAST BY ENSEMBLE MEANS IN AN INCREASINGLY HIGH AMPLITUDE MEDIUM RANGE PATTERN. DETERMINISTIC MODEL RUN-RUN CONSISTENCY HAS BEEN SUBPAR LATELY WITH SMALL-MID SCALE EMBEDDED SYSTEMS. HEIGHTS ARE FORECAST TO STRONGLY BUILD FROM THE GULF OF AK/SE AK TO THE INTERIOR IN RESPONSE TO AN AMPLIFIED UPPER LEVEL LOW/TROUGH DEVELOPMENT OVER THE BERING SEA. A DEEPENED LOW STORM TRACK SETS UP FROM THE NORTH PACIFIC UP ACROSS THE ALEUTIANS/SW AK AND THE BERING SEA...WITH MORE BENIGN WEATHER/MODEST OVERRUNNING SNOW POTENTIAL OVER THE INTERIOR AND NORTH SLOPE. DEEPENED LOWS/FRONTS AND THEIR HIGHLY UNSETTLED WEATHER FOCUS SHOULD HAVE A HARD TIME PRESSING EASTWARD THROUGH THE GULF OF AK AS THEY ENCOUNTER PERSISTENT DOWNSTREAM RIDGING. IN ADDITION TO MARITIME INTERESTS...A SIGNIFICANT THREAT FOR HEAVY WEATHER/PRECIPITATION WILL FOCUS FROM THE ERN ALEUTIANS/SW AK ONWARD WITH DURATION ONSHORE FETCH INTO SRN AND TO A LESSER EXTENT SERN AK AS ENHANCED BY COASTAL TERRAIN LIFT. ACCORDINGLY AND AS PER COLLABORATION WITH ALASKAN NWS FORECAST OFFICES...USED AN ENSEMBLE MEAN BASED FORECAST STRATEGY BASED FROM THE 06 UTC GEFS MEAN AND WELL CLUSTERED 00 UTC NAEFS/ECMWF ENSEMBLE MEAN GUIDANCE IN LUE OF LESS RUN TO RUN CONSISTENT DETERMINISTIC MODEL GUIDANCE. THIS MAINTAINED GOOD WPC FORECAST CONTINUITY. OFFSHORE SURFACE LOWS WERE MANUALLY ADJUSTED TO BE A BIT DEEPER THAN THE ENSEMBLE MEANS CONSIDERING DETERMINISTIC MODEL TRENDS AND DYNAMIC SUPPORT ALOFT. SCHICHTEL