ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 238 PM EDT MON MAY 04 2015 VALID 12Z FRI MAY 08 2015 - 12Z TUE MAY 12 2015 ...ALASKAN PATTERN OVERVIEW AND SENSIBLE WEATHER/THREATS HIGHLIGHTS... THE SLOW PROGRESSION OF AN AMPLIFIED MID-UPPER LEVEL TROUGH STILL SUPPORTS A LEAD ORGANIZED SURFACE LOW TRACK OVER THE GULF OF AK INTO FRI AND THE WEEKEND. EXPECT UNSETTLED GULF MARITIME CONDITIONS AND TERRAIN ENHANCED PRECIPITATION WRAPPED INTO SRN AK. AN AMPLIFIED RIDGE BUILDS IN ADVANCE FROM WRN CANADA TO A WARMED ALASKAN INTERIOR/N SLOPE INTO NEXT WEEKEND BEFORE NRN STREAM HEIGHT FALLS EASE IN. UNDERNEATH...FORECAST SPREAD AND UNCERTAINTY IS GREATER WITH SEVERAL COMPLEX INTERMEDIATE LOWS/UNSETTLING WEATHER THAT WORKS NEAR/SOUTH OF THE ALEUTIANS THEN SW AK DAYS 5-7 SAT-NEXT MON THAT SHOULD EMERGES INTO THE GULF OF AK IN THE WAKE OF THE LEAD SYSTEM. THIS MAY BE FOLLOWED BY A DEEPER LOW APPROACH TOWARD THE WRN ALEUTIANS IN ABOUT A WEEK OR SO THAT ACTUALLY SEEMS BETTER REPRESENTED BY ENSEMBLE CLUSTERS. DETERMINISTIC MODELS ARE STILL QUITE VARIED THOUGH. ...GUIDANCE AND UNCERTAINTY ASSESSMENT... THE WPC ALASKAN MEDIUM-RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM THE 00 UTC ECMWF FRI AS PER COORDINATION WITH WFO ANCHORAGE THAT OFFERRED PREFERENCE FOR ASSOCIATED FRONTAL AND PRESSURE GRADIENT DETAILS. QUICKLY INCREASING FORECAST SPREAD SAT FAVORS QUICK TRANSITION FROM DETERMINISTIC GUIDANCE TO THE 06 UTC MEAN FOR THE REMAINDER OF THIS FORECAST PERIOD. THIS ENSEMBLE MEAN SEEMED TO PROVIDE THE BEST TRANSITION...BUT OVERALL MEDIUM-RANGE PREDICTABILITY IS BELOW AVERAGE. SCHICHTEL