Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 619 PM EDT Wed Jul 12 2023 Valid 12Z Sun Jul 16 2023 - 12Z Thu Jul 20 2023 ...Guidance Evaluation/Preferences and Predictability Assessment... The WPC Alaskan medium range product suite was primarily derived from a composite blend of the 12 UTC GEFS/NAEFS/ECMWF ensemble means given even less stellar run to run continuity in the models in this sensitive pattern. Most of the latest model and ensemble guidance excluding the 12 UTC UKMET has strongly trended toward a more rapid southward shifted trend for upper trough energies down through western Alaska to the Gulf of Alaska through this forecast period. This was hinted by yesterdayā€s 12 UTC Canadian model. This trend seems reasonable given upstream ridge amplitudes. Despite the continuity change again today, it is also notable though that it seems this big trend has roots in the more predictable short range period across the high latitudes. ...Weather/Hazards Highlights... Ample upper level support and lower atmospheric moist inflow ahead of deep and now more southward digging Bering Sea/western Alaskan mean troughing will lead to bouts of moderately heavy rains across particularly from Southwest Alaska to the Alaska Peninsula and Kodiak Island/Kenai Peninsula/vicinity this weekend, with less organizated activity also spreading into much of the Mainland and southern tier areas into next week. Southwest Alaska seems to have the best chance for locally heavier rains and unsettled weather conditions in proximity to a main surface low and frontal system associated with upper trough/height falls passage this weekend. Otherwise, rainfall amounts do not look to be too heavy overall, but more showery and diurnally driven, with enhanced amounts possibly also into the western Alaska Range. The carving out of an amplified and slow moving closed upper trough and surface based low over the Gulf of Alaska to the lee of a highly anomalous upper ridge may present a protracted maritime concern next week. Schichtel Hazards: - Heavy rain across portions of southwestern Alaska and the Alaska Peninsula, Sat, Jul 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