Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1241 PM EST Mon Feb 11 2019 Valid 12Z Fri Feb 15 2019 - 12Z Tue Feb 19 2019 ...Guidance/Uncertainty Assessment... GFS/ECMWF and GEFS/NAEFS/ECMWF ensemble means overall cluster reasonably well for the next week despite lingering smaller scale embedded system variance. The WPC Alaskan medium range forecast product suite was mainly derived from a composite blend. Manual adjustments were applied to the blend to depict deeper offshore low pressure centers consistent with favorable support aloft in a stormy pattern with above normal forecast predictability. ...Pattern and Weather/Threats Highlights... A deepened leading low/frontal system exits the southeastern Gulf of Alaska by Friday, cut underneath a stalled lingering frontal drape pushed just offshore southeast Alaska. Models and ensembles build a mean upper ridge up over the interior late week into the weekend. This occurs as high pressure builds over the mainland and northwest Canada. Pattern amplification will tend to shield the eastward progression of a new upstream series of potentially deep and stormy late weeklow pressure systems over the western half of the Bering Sea and Aleutians. Maritime interest threatening high wind/waves and precipitation will be able to work increasingly toward western/southwestern Alaska and the AKpen/Gulf of AK with triple point low developments underneath over the weekend into next week as the effects from ejecting impulse energies act to slowly shift eastward and deamplify the shielding downstream ridge. Schichtel 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 http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html