ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 410 PM EDT TUE JUL 11 2017 VALID 12Z SAT JUL 15 2017 - 12Z WED JUL 19 2017 PATTERN OVERVIEW MODEL ASSESSMENT/PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ MODEL GUIDANCE THIS MORNING SHOWS A FEW SALIENT SYNOPTIC FEATURES IN THE MEDIUM-RANGE. AN UPPER-LEVEL CLOSED LOW OFF ALASKAN PANHANDLE WILL CONTINUE TO WEAKEN AS IT MOVES ONSHORE. ANOTHER CLOSED LOW OVER EASTERN SIBERIA WILL SWING OFFSHORE INTO THE BERING SEA BEFORE APPROACHING MAINLAND ALASKA ON DAY 8 NEXT WEDNESDAY. MEANWHILE...A COOL AIRMASS FROM THE ARCTIC OCEAN WILL EDGE CLOSER TO THE NORTH COAST OF ALASKA. THE ENSEMBLE MEANS FROM MAJOR GLOBAL MODELS AGREE WITH THIS GENERAL SCENARIO WITH THE 06Z GEFS BEING ON THE SLOW SIDE WHILE THE 00Z EC MEAN ON THE FAST SIDE. THE FINAL WPC ALASKAN GRIDS WERE DERIVED FROM AN EQUAL BLEND OF THE 00Z ECMWF WITH THE 00Z NAEFS BEGINNING ON DAY 4...AND PROGRESSIVELY TRENDING TOWARD THEIR RESPECTIVE ENSEMBLE MEANS BY DAY 7 AND 8. IN ADDITION...A 15%/20% OF THE 06Z GFS HAS BEEN INCLUDED ON DAY 7/8 IN FAVOR OF A SLOWER SOLUTION REGARDING THE BERING SEA SYSTEM. WEATHER IMPACTS ~~~~~~~~~~~~~~~ HIGH TEMPERATURES OVER INTERIOR ALASKA WILL COOL DOWN SLIGHTLY FROM THE LOW 80S INTO THE UPPER 70S AS THE UPPER-LEVEL SYSTEM APPROACHES. COOL AIR FROM THE ARCTIC OCEAN SHOULD KEEP TEMPERATURES BELOW 60 DEGREES ON THE NORTH SHORE. NO SIGNIFICANT PRECIPITATION IS EXPECTED BEFORE THE FIRST WAVE OF MOISTURE MOVES FROM SOUTH TO NORTH UP THE WEST COAST FROM FRIDAY THROUGH THE WEEKEND. THIS WILL BE FOLLOWED BY THE ARRIVAL OF THE BERING SEA SYSTEM ACROSS THE ALEUTIANS AND INTO THE WEST COAST EARLY NEXT WEEK. THE HIGH ELEVATIONS OF SOUTHERN ALASKA WILL CONTINUE TO SEE TERRAIN-INDUCED PRECIPITATION THROUGH THE MEDIUM-RANGE PERIOD. FARTHER SOUTHEAST...COOL AND SHOWERY CONDITIONS ARE EXPECTED TO PERSIST ACROSS THE ALASKAN PANHANDLE AS THE WEAKENING UPPER LOW APPROACHES. KONG