ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 235 PM EDT THU APR 09 2015 VALID 12Z MON APR 13 2015 - 12Z FRI APR 17 2015 THE 9/00Z ECENS...GEFS ENSEMBLE MEANS DETERMINISTIC ECMWF WERE UTILIZED TODAY---TO DEPICT THE AMPLIFYING PATTERN ANTICIPATED TO EMERGE ACROSS THE NORTHEAST PACIFIC. THROUGH DAY 6...THE KEY FEATURE WILL BE AN INTENSIFYING SURFACE LOW---FORMING THE BASE OF AN UPPER-LEVEL TROUGH---WHICH IS CURRENTLY ESTABLISHING ITSELF ALONG 160W. PRIOR TO DAY 6...UNSTABLE AIR WILL MIGRATE SOUTHEASTWARD FROM THE SOUTHERN BERING SEA INTO THE NORTHWEST GULF OF ALASKA---ACROSS THE NORTHEAST PACIFIC AND INTO THE MAINLAND'S PACIFIC NORTHWEST. A SUB-SYNOPTIC SCALE LOW PRESSURE CENTER FORMING JUST SOUTHEAST OF THE KENAI PENINSULA---ALONG WITH ORGANIZING UPPER-LEVEL ENERGY OFF THE EAST ASIAN PENINSULA OF KAMCHATKA---WILL APPARENTLY ATTEMPT TO CONSOLIDATE ALONG 50N 150W BETWEEN DAYS4-6. THE 9/00Z DETERMINISTIC ECMWF ARE IN VERY GOOD AGREEMENT WITH THE DEPTH AND LAT/LONG POSITION OF THE SURFACE LOW AT DAY 6---WITH THE 9/00Z DETERMINISTIC GFS A TAD FURTHER NORTH WITH THIS FEATURE. THE RATHER GOOD AGREEMENT AT THE SURFACE FOR DAY 6---COINCIDES WITH THE UPPER-LEVEL FLOW PATTERN DOWNSTREAM---AND ITS AMPLIFIED CONFIGURATION ALONG 130W FORM THE MID-LATITUDE EAST PACIFIC OCEAN NORTHWARD INTO WESTERN CANADA. THIS UPPER-LEVEL RIDGE ALONG THE WEST COAST COAST OF NORTH AMERICAN SHOULD TURN THE DEEPENING DAY 6 SURFACE CYCLONE NORTHEASTWARD---AND MIGRATE IT INTO THE NORTHWEST GULF AND SOUTHWEST COAST OF ALASKA ON/AROUND DAY 7. THE 2 MAIN CHALLENGES THIS FORECAST PERIOD WILL BE... (1) WHAT OCCURS UPSTREAM ALONG 50N BETWEEN THE DATELINE AND 170E LATITUDE---IN RESPONSE TO THE DOWNSTREAM TROUGH-RIDGE COUPLET AND THE OUTCOME OF ITS AMPLIFICATION? AND (2) THE MIGRATORY TRACK OF THE DAY 6-8 SYSTEM---MOVING THROUGH THE ALEUTIANS AND NORTHWEST GULF OF ALASKA. PERTAINING TO CHALLENGE (1) WOULD HAVE TO BELIEVE THAT THE TROUGH-RIDGE COUPLET SHOULD SPREAD SOME BROAD-SCALE MOISTURE AND PACIFIC AIR NORTHEASTWARD ACROSS THE PANHANDLE AND EASTERN ALASKA---BUT WEAKEN ALONG THE WESTERN PERIPHERY OF THE UPPER-LEVEL RIDGE AXIS. TO WHAT EXTENT THIS MOISTURE CONTINUES TO MIGRATE NORTHWESTWARD---ACROSS THE CENTRAL AND NORTHWEST PORTIONS OF THE INTERIOR---AND IN WHAT STATE (WEAK OR MODERATELY-ORGANIZED FORM) REMAINS UNCLEAR. PERTAINING TO (2) THAT OUTCOME---WILL HAVE A DIRECT RELATIONSHIP TO THE SECOND OR 'NEW' CYCLONE TRACK AROUND DAY 6-7---INVOF THE DATELINE. FOR NOW...USED A 70/30 BLEND OF THE ECENS/GEFS RESPECTIVELY---TO START THIS CYCLONE ON MORE OF A EAST-SOUTHEASTWARD BOUND TRACK ALONG THE ALEUTIANS---AND 'UNDERNEATH' THE 'WAKE' OF THE LEAD TROUGH-RIDGE COUPLET. VOJTESAK