ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 312 PM EDT MON JUN 19 2017 VALID 12Z FRI JUN 23 2017 - 12Z TUE JUN 27 2017 THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ON THE LARGE SCALE PATTERN ACROSS ALASKA FRIDAY THROUGH TUESDAY (DAY 4-8). AN UPPER LEVEL RIDGE OVER ALASKA WITH 564-570DM HEIGHTS IS EXPECTED TO PERSIST THROUGH THIS FORECAST PERIOD. LOWER MID-LEVEL HEIGHTS ASSOCIATED WITH AN UPPER LEVEL LOW OVER THE BERING SEA AND ANOTHER OVER THE NORTHERN GULF OF ALASKA ARE ALSO PROGGED BY THE GUIDANCE SOUTH OF THE RIDGE AXIS. UNCERTAINTY GROWS BY SUNDAY AND BEYOND WITH RESPECT TO A COUPLE SHORTWAVES ROTATING THROUGH THE WESTERN ALEUTIANS AND INTO THE BERING SEA. THE WPC FORECAST WAS BASED ON A BLEND OF THE 12Z GFS/00Z ECMWF ALONG WITH THE 00Z EC MEAN/6Z GEFS MEAN, WITH HEAVIER WEIGHT PLACED ON THE DETERMINISTIC SOLUTIONS FOR DAYS 4-5, AND HEAVIER WEIGHT PLACED ON THE ENSEMBLES FOR DAYS 6-8. WHILE FORECAST CONFIDENCE IN THE LARGE SCALE PATTERN IS AVERAGE, THE CONFIDENCE IN THE SMALLER SCALE DETAILS OF INDIVIDUAL SHORTWAVE EVOLUTION IS BELOW AVERAGE, AND LIKELY DUE TO THE SOMEWHAT BLOCKY NATURE OF THE FLOW. THIS PATTERN SHOULD KEEP MUCH OF MAINLAND ALASKA RELATIVELY DRY AND WARM, WITH PRECIP INCREASING ACROSS THE ALEUTIANS THROUGH THE PERIOD. HIGHS COULD REACH THE MID TO UPPER 70S ACROSS PORTIONS OF THE INTERIOR BY EARLY NEXT WEEK WITH THE UPPER LEVEL RIDGE IN PLACE. EVEN THE ARCTIC COAST WARMS UP SOME WITH HIGHS IN THE 40S FOR THE IMMEDIATE COAST AND 50S JUST INLAND. THE BEST CHANCES FOR RAINFALL ARE EXPECTED FOR THE CENTRAL AND WESTERN ALEUTIANS IN ASSOCIATION WITH THE BERING SEA LOW, AND THE EASTERN PANHANDLE BY SUNDAY AS THE GULF LOW SLOWLY MOVES TOWARD THAT REGION AND WEAKENS. HAMRICK