Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 236 PM EDT Sat Mar 16 2019 Valid 12Z Wed Mar 20 2019 - 12Z Sun Mar 24 2019 ...Weather Highlights/Hazards... The models and ensembles still show a pattern favorable for multiple periods of terrain and coastal convergence enhanced precipitation into the southern coast of the Mainland into Southeast Alaska through medium range time scales. Moist inflow will continue to wrap around a active series of deepened Gulf of Alaska surface lows that re-develop as energies work under influence of an amplified mid-upper level mean trough/closed low. Systems will tap an atmospheric river to produce daily totals averaging several inches with some locally favored 5-day totals of 10+ inches. The airmass quickly loses moisture content farther inland, but expect modest snows from southwest Alaska to the western/central Interior to northern Alaska as energy lifts in a channel between a Bering Sea mean mid-upper level trough/low and an Interior Alaska/western Canadian mid-upper level ridge. Relatively dry conditions are expected to persist for much of the east-central Interior under that ridge. Meanwhile upstream, expect increasingly stormy conditions for the southern Bering Sea/Aleutians mid-late next week then again next weekend with deep surface low developments under a mean closed upper low/trough position. This storm track has settled slightly southward compared to yesterdays guidance. Highly unsettled weather will accordingly work steadily eastward with system progression toward the Alaska Peninsula/southwest Alaska in advance of and with triple point low transitions downstream of the parent lows. ...Guidance Assessment... Overall, the WPC Alaskan Days 4-8 product suite was mainly derived from the ECMWF ensemble mean to maintain as much continuity as feasible in this complex pattern. However, included smaller inputs from the latest GEFS mean and GFS/ECMWF models to show a bit better detail as consistent with uncertainty. Offshore lows were further deepened considering favorable support aloft and pattern history. Schichtel Bullet points from the WPC Days 3-7 Hazards chart can be found at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html