ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 307 PM EST SUN DEC 25 2016 VALID 12Z THU DEC 29 2016 - 12Z MON JAN 02 2017 THE LARGE-SCALE PATTERN ACROSS THE REGION WILL FEATURE RATHER AMPLIFIED FLOW THROUGHOUT THE FORECAST PERIOD. ON THURSDAY MORNING...A STOUT UPPER RIDGE INITIALLY OVER THE WESTERN HALF OF AK WILL GRADUALLY MOVE EASTWARD AND FLATTEN IN RESPONSE TO A POWERFUL UPPER TROUGH MOVING THROUGH THE BERING SEA. COMPARED TO RECENT DAYS...MOST OF THE SOLUTIONS WERE COMPARABLE WITH THE POSITION OF THE DEEP SURFACE CYCLONE MOVING TOWARD THE THE KAMCHATKA PENINSULA. THE GENERAL CONSENSUS FAVORED PRESSURES IN THE 950 TO 955 MB RANGE ON 29/1200Z ALTHOUGH THE PAST FEW RUNS OF THE GFS WERE 15 TO 20 MB WEAKER. SOME COMBINATION OF THE 00Z ECMWF/CMC/UKMET AS WELL AS THE ENSEMBLE MEANS WERE REASONABLE...AT LEAST EARLY IN THE PERIOD. MOVING AHEAD...MODELS VARY WITH THE INTENSITY OF THIS UPPER TROUGH AS THE CORE OF LOWER HEIGHTS CROSSES EXTREME NORTHERN AK INTO THE ARCTIC OCEAN WHICH LED TO MORE OF A PUSH TOWARD THE ENSEMBLE REALM. ADDITIONALLY...RE-AMPLIFYING FLOW UPSTREAM CONTAINED A SERIES OF SHORTWAVE DETAIL DIFFERENCES. AT THIS POINT...THE 00Z CMC SEEMED TO BE TOO FLAT WITH MID-LEVEL HEIGHTS BETWEEN THE PAIR OF SYSTEMS WHICH DID NOT LOOK REASONABLE BASED ON THE PATTERN. LOOKING INTO NEXT WEEKEND...EXCEPT FOR THE 00Z CMC...ALL MODELS AGREE ON A HIGHLY MERIDIONAL SIGNATURE TO THE PATTERN FOR DAYS 6 THROUGH 8 WITH THE PAST COUPLE OF ECMWF/ECMWF ENSEMBLE MEAN SOLUTIONS BEING MUCH STRONGER. WHILE POSSIBLE GIVEN THE ECMWF SUITE CONSISTENCY HERE...DO NOT WANT TO ADD ANY ECMWF DETERMINISTIC WEIGHT HERE GIVEN THE LOW SKILL. REGARDLESS...IT APPEARS AN UPPER RIDGE IS EXPECTED TO BE A MAINSTAY FEATURE ACROSS A MAJORITY OF AK INTO THE EARLY PART OF THE NEW YEAR. MOST MODELS FAVOR ALL UPSTREAM SHORTWAVE ENERGY TO LIFT TOWARD THE POLAR REGIONS RATHER THAN PUSHING THE RIDGE INTO THE YUKON TERRITORY. AS MENTIONED EARLIER...SOME FORM OF CONSENSUS AMONG THE 00Z ECMWF/CMC/UKMET AND THE ENSEMBLE MEANS WAS UTILIZED FOR DAY 4 BEFORE MOVING AWAY FROM THE DETERMINISTIC SOLUTIONS AND FAVORING A 50/50 SPLIT OF THE 00Z ECMWF/NAEFS ENSEMBLE MEANS THEREAFTER. CONFIDENCE IS GENERALLY ABOVE AVERAGE IN THE SYNOPTIC SETUP BUT CLOSER TO AVERAGE WITH THE DETAILS OF THE ACTIVE FLOW WEST OF AK. THE FORECAST REGIME IN PLACE WILL FAVOR ABOVE NORMAL TEMPERATURES GIVEN THE PRESENCE OF RIDGING ALOFT...ESPECIALLY LATER INTO THE MEDIUM RANGE PERIOD. EARLY ON...EXPECT AN INCREASE IN PRECIPITATION OVER THE AK INTERIOR GIVEN THE PASSAGE OF THE LONGWAVE TROUGH. RUBIN-OSTER