Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 350 PM EDT Tue Jun 05 2018 Valid 12Z Sat Jun 09 2018 - 12Z Wed Jun 13 2018 A strong upper high over Siberia (500mb height anomalies around +2 to +3 sigma) will favor downstream progressive flow just south of mainland Alaska along 50N. Ensemble consensus then builds in heights through the interior but the 00Z ECMWF appeared much too aggressive here which disrupted the pattern to the south to be out of line with the ensemble means (ECMWF/GEFS). The 12Z GFS (and 00Z GFS) were more consistent with the means and formed most of the detail to the forecast. This maintained good continuity from the forecast yesterday which keeps the lead system south of the Aleutians Sat-Mon as it attempts to lift into the Gulf next week (but should weaken/dissipate as it loses support aloft). Another system may track out of the north Pacific next week, again south of the Aleutians per the ensembles. Fracasso WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can be found at: http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif www.wpc.ncep.noaa.gov/alaska/akmedr.shtml http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html