ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 213 PM EST WED NOV 18 2015 VALID 12Z SUN NOV 22 2015 - 12Z THU NOV 26 2015 LONGWAVE PATTERN WILL TREND TOWARD INCREASED AMPLIFICATION DUE TO UPSTREAM AND DOWNSTREAM BUCKLING OF THE FLOW. THIS SHOULD PUSH RIDGING INTO EASTERN ALASKA EAST OF ABOUT 150W EARLY NEXT WEEK AHEAD OF A ROBUST BERING SEA SYSTEM. BY LATER IN THE PERIOD, THE FORECAST BECOMES LESS CLEAR AS THE MODELS/ENSEMBLES DIVERGE IN THE WESTERN/CENTRAL PACIFIC WITH REGARD TO THE TRACK OF TYPHOON IN-FA. FOR SUN-TUE, THE RECENT MODELS/ENSEMBLES OFFER A REASONABLE CLUSTER OF SOLUTIONS, WHICH TAKES ONE WEAK SYSTEM ACROSS SW ALASKA INTO THE GULF WHILE THE BIGGER SYSTEM PUSHES THROUGH THE WESTERN/CENTRAL BERING -- NEAR THE DATELINE -- AND SENDS A SURGE OF WARMER AIR NORTHWARD THROUGH MUCH OF THE MAINLAND. 850MB TEMPERATURES ARE FORECAST TO REACH NEAR 0C IN SW AK AND POSSIBLY NORTHWARD TOWARD THE ARCTIC CIRCLE, THOUGH IT WILL LIKELY NOT BE REALIZED AT THE SURFACE THAT FAR NORTH. ABOVE FREEZING SURFACE TEMPERATURES ARE FORECAST FOR SW ALASKA AND POSSIBLY EASTWARD NORTH OF THE ALASKA RANGE AND NORTHWARD ALONG THE BERING COAST. GIVEN THE DOWNSTREAM PATTERN OF A DIGGING TROUGH INTO THE CONUS PAC NW, FELT A STRONG RIDGE IN EASTERN ALASKA WAS WARRANTED. USED A COMBINATION OF THE 12Z GFS AND 00Z ECMWF/UKMET. BY NEXT TUE-WED, FOCUS TURNS TO AN APPROACHING SYSTEM OR SYSTEMS FROM THE W PACIFIC. AT THIS TIME, IT'S UNCERTAIN HOW QUICKLY TYPHOON IN-FA WILL RECURVE INTO THE WESTERLIES. THE 12Z GFS WAS QUICKEST AND THIS SYSTEM WOULD APPROACH THE ALEUTIANS BY NEXT THURSDAY. THE 00Z ECMWF WAS SLOWER BUT ALSO WEAKER WITH THE SYSTEM. THE JTWC AND JMA FORECASTS WERE SOMEWHAT IN BETWEEN BUT SHOW RECURVATURE IN 5 DAYS LIKE THE GFS, WHICH SHOWED A STRONGER SYSTEM. GFS MAY HAVE THE EDGE ON HANDLING THIS SYSTEM, BUT CONFIDENCE IS LOW IN IMPACTS TO THE HIGH LATITUDES JUST YET. OTHER FACTOR WILL BE INCOMING NORTHERN STREAM ENERGY OFF ASIA EARLY NEXT WEEK WHICH SHOULD ENTER THE BERING WED-THU, PERHAPS DEPENDING ON THE EVOLUTION TO THE SOUTH. TRENDED TOWARD A BLEND OF THE 12Z GFS AND 06Z GEFS/00Z ECENS MEANS. STRONG RIDGING INTO THE MAINLAND SHOULD ALSO SUPPORT A STRENGTHENING SURFACE HIGH IN THE YUKON AROUND TUESDAY NEXT WEEK, WHICH COULD ALLOW COLDER AIR TO INVADE THE PANHANDLE. 12Z GFSMOS BLENDED WITH THE 00Z ECENS/NAEFS MEANS OFFERED A REASONABLE FORECAST FOR TEMPS/POPS. FRACASSO