ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 208 PM EDT FRI APR 28 2017 VALID 12Z TUE MAY 02 2017 - 12Z SAT MAY 06 2017 AN UPPER LOW IS FORECAST TO LIFT INTO THE GULF MIDWEEK AND WEAKEN AS ANOTHER ONE FROM THE WESTERN BERING SEA SLIDES EAST ALONG 50N NEXT FRI/SAT. THE ENSEMBLES WERE GENERALLY IN AGREEMENT THROUGH THE PERIOD (06Z GEFS AND 00Z ECMWF ENSEMBLE MEAN) WHICH WOULD OTHERWISE LEAD TO ABOVE AVERAGE CONFIDENCE, BUT THE EMBEDDED SYSTEMS REMAIN SOMEWHAT POORLY HANDLED BY RECENT DETERMINISTIC GUIDANCE. OVERALL, CONFIDENCE IS AVERAGE BUT ABOVE AVERAGE IN THE SYNOPTIC SETUP. USED A BLEND OF THE 12Z/06Z GFS WITH THE 06Z GEFS MEAN AND 00Z ECMWF/ECMWF ENSEMBLE MEAN. LEAD SYSTEM SHOULD MOVE INTO THE GULF AND DEEPEN BUT THE MODELS/ENSEMBLES DIVERGE N-S (SPEED) AND E-W (TRACK) AS WELL AS DEPTH (970-990MB) DEPENDING ON HOW AN UPSTREAM VORTICITY INTERACTS/ADVECTS INTO (OR PAST) THE MAIN SYSTEM. ENSEMBLES SUGGEST MODEST DEEPENING (CLOSED 984MB ISOBAR IN THE ECMWF ENSEMBLE MEAN) AND THIS WAS CONSISTENT WITH THE 06Z GFS. PARENT LOW SHOULD GET LEFT BEHIND IN THE GULF ON THURSDAY AS THE FRONT PUSHES INTO CANADA. NEXT SYSTEM SHOULD PUSH INTO THE WESTERN ALEUTIANS AROUND WEDNESDAY THOUGH THE MODELS/ENSEMBLES CANNOT FIGURE OUT HOW TO HANDLE THE FLOW OFF EASTERN ASIA (GFS RUNS WERE MORE PROGRESSIVE WITH NORTHERN STREAM ENERGY UNLIKE THE 00Z ECMWF/UKMET). NEVERTHELESS, ALL COMES TOGETHER INTO ANOTHER SYSTEM LIKELY JUST SOUTH OF THE ALEUTIANS THU-SAT. AGAIN, CONSENSUS BLEND SUFFICED WHICH WAS NEAR WPC CONTINUITY. RATHER WET PERIOD FOR SE PORTIONS INTO THE PANHANDLE BUT NOTHING OUT OF THE ORDINARY. THIS SHOULD KEEP DAYTIME TEMPERATURES BELOW AVERAGE. WESTERN INTERIOR WILL SEE ABOVE AVERAGE TEMPERATURES UNDER WEAK RIDGING WHILE THE NORTH SLOPE WILL BE CLOSE TO AVERAGE UNDER WEAK TROUGHING. FRACASSO