ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 149 PM EST SAT DEC 26 2015 VALID 12Z WED DEC 30 2015 - 12Z SUN JAN 03 2016 ...STORMY ALASKAN LOWS WITHIN AN AMPLIFYING FLOW PATTERN... ...GUIDANCE/UNCERTAINTY ASSESSMENT... THE MODELS AND ENSEMBLES CONTINUE TO OFFER A QUITE SIMILAR MID-LARGER SCALE PATTERN EVOLUTION ACROSS MEDIUM RANGE TIME SCALES. THIS SUGGESTS ABOVE NORMAL FORECAST PREDICTABILTY DESPITE LESS CERTAIN SMALLER SCALE SYSTEM DEVELOPMENTS. THAT SAID...06 UTC GFS AND 00 UTC ECMWF DETERMINISTIC GUIDANCE WAS LESS VARIED TODAY WITH THE MORE SIGNIFICANT SURFACE LOWS...BOLSTERING CONFIDENCE SOME AT LEAST INTO NEW YEAR DAY. LATER GUIDANCE FROM THE 12 UTC GFS/ECMWF WAS GENERALLY ALSO IN LINE WITH THIS. ACCORDINGLY...THE WPC ALASKAN MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A COMPOSITE BLEND OF REASONABLY WELL CLUSTERED AND COMPATABLE GUIDANCE FROM THE 06 UTC GFS/GEFS MEAN AND 00 UTC ECMWF/ECMWF ENSEMBLE MEAN. REDUCED THE INPUT OF THE GFS/ECMWF AFTER DAY6/FRI. WPC CONTINUITY FROM YESTERDAY WAS WELL MAINTAINED...ALBEIT WITH THE INPUT FROM THE GFS/ECMWF AND ADDITIONAL MANUALLY APPLIED ADJUSTMENTS FAVORING DEEPER BERING SEA/GULF LOW POTENTIAL. THIS SEEMS LIKE A REASONABLE TREND GIVEN OVERALL SUPPORT ALOFT IN GUIDANCE AND AS THE MAIN LOWS HAVE ORIGINS WITH ENERGETIC/PROGRESIVE FLOW FROM DATA RICH ERN ASIA. ...PATTERN HIGHLIGHTS/THREATS... GUIDANCE SHOWS GOOD AGREEMENT ALOFT WITH DEVELOPMENT OF AN AMPLIFIED PATTERN HIGHLIGHTED BY A SLOW MOVING CLOSED MEAN LOW OVER THE BERING SEA TO FOCUS WINDS/WAVES/WEATHER. MEANWHILE...STABLE RIDGE BUILDING FROM WRN CANADA NWWD INTO THE ALASKAN INTERIOR SHOULD ACT TO LIMIT PRECIPITATION. THIS OVERALL PATTERN INSTEAD BRINGS HEAVIER PCPN ACROSS THE ALEUTIANS/SW/FAR WRN AK IN CLOSER PROXIMITY TO THE CLOSED LOW CIRCULATIONS. HEAVY WINDS/WAVES/PRECIPITATION IS ALSO LIKELY WITH VERY DEEP/MOIST PACIFIC BASED SURFACE LOWS/SYSTEMS RIDING UP THROUGH THE WRN GULF OF AK ON THE WRN PERIPHERY OF THE AMPLIFIED DOWNSTREAM MID-UPPER LEVEL RIDGE. THIS WILL ACT TO PROLONG A LEAD EXCESSIVE PRECIPITATION THREAT FOCUS INTO FAVORED TERRAIN OF SRN ALASKA WITH PROLONGED GULF INFLOW...WITH LESS CONSISTENT EMPHASIS INTO SERN AK. SCHICHTEL