Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 354 PM EDT Sun Mar 17 2019 Valid 12Z Thu Mar 21 2019 - 12Z Mon Mar 25 2019 ...Weather Highlights/Hazards... Latest models and ensembles continue to highlight a pattern quite favorable for multiple periods of terrain and coastal convergence enhanced precipitation especially into the southern coast of the Mainland as well into Southwest and northern Southeast Alaska through this medium range period. Moist inflow will continue to wrap around an 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 atmospheric rivers to produce daily totals averaging several inches with some additional and locally favored 5-day totals of 10+ inches. The airmass quickly loses moisture content farther inland, but continue to expect modest snows inland 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. 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 deep parent lows. ...Guidance Assessment... After consultation with local Alaskan WFOs, the WPC Alaskan Days 4-8 product suite was mainly derived from a blend of well clustered guidance from the 00 UTC ECMWF ensemble mean and deterministic ECMWF/Canadian models. This combination shows detail/offshore storm intensities consistent with average predictability, favorable dynamic support and pattern history, but offer potential to be quite deep. We'll monitor this threat into shorter time frames. Recent GFS/GEFS runs have been seemingly too progressive with systems eminating across the north Pacific but the latest 12 UTC versions have at least trended slower. 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