Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 716 PM EDT Wed May 11 2022 Valid 12Z Sun May 15 2022 - 12Z Thu May 19 2022 ...Overview and Guidance/Predictability Assessment... The upper flow pattern across Alaska over the next week looks to remain quite amplified/blocky as highlighted by strong ridging over the Bering Sea and an elongated trough from the Mainland into the Gulf of Alaska containing high latitude system energies from the Arctic. One shortwave looks to drop through the western Mainland next weekend helping to reinforce a large closed trough/low over the Gulf. This low looks to meander into early next week before it may finally weaken and get pushed east as the pattern begins to break down some and become less blocky. Despite lingering differences in the details, a composite blend of the latest 12z deterministic models seemed to offer a good starting point for the first half of the forecast period, although the 12z CMC was notably stronger/faster with energy rounding the top of the ridge across eastern Siberia into the Arctic. Bigger uncertainties begin to arise later in the period regarding reinforcing energy into the Gulf low and also systems moving across the Mainland. There are also differences regarding how quickly the low in the Gulf weakens and moves into western North America. The GFS/CMC are a little faster than the ECMWF and ensemble means. Given these uncertainties which continue to vary in model run to run continuity, the WPC forecast trended more towards the ECENS/GEFS ensemble means by the second half of the period, with some inclusion of the GFS and ECMWF for a little added definition to systems. This forecast plan maintains decent WPC Alaskan product continuity. ...Weather and Hazard Highlights... Increased light and periods of moderate precipitation are likely to organize and shift southward across portions of Mainland Alaska this weekend into next week as upper disturbances and several well organized surface fronts work across the area. There is some threat for stronger and gusty winds, mainly over the western mainland, as pressure gradients tighten with system passages. Some river flooding is expected to be ongoing associated with snow melt and ice jams in some locations across the Mainland as well. Offshore to the south, regeneration through the weekend and into early-mid next week of a well organized upper low/trough and associated surface system position over the Gulf of Alaska will also favor a periodic focus for moderate and terrain enhanced precipitation over Southeast Alaska/Panhandle. Temperatures across much of the Mainland into at least early next week will remain below normal, with much below normal values in some places, especially parts of northern Alaska as a deeper shortwave drops in through the region. Temperatures may moderate some again around Tuesday-Wednesday, though still below normal. Parts of Western Alaska and the Peninsula may finally get above normal though as the Bering Sea ridge begins to move into the region. Santorelli Hazards: - Flooding possible across portions of mainland Alaska, Sat-Sun, May 14-May 15. Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart 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