Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 700 PM EDT Fri Jul 14 2023 Valid 12Z Tue Jul 18 2023 - 12Z Sat Jul 22 2023 ...Guidance Evaluation/Preferences and Predictability Assessment... Recent model and ensemble forecast clustering and run to run continuity problems have improved, but remain an issue above the Arctic Circle. The 12 UTC GFS/UKMET hold lead upper troughing over Northwest Alaska next week until the approach of Bering Sea energies, probably more in line with the multi-model ensembles than the 12 UTC ECMWF/Canadian that use higher latitude Arctic Ocean energies to kick the Northwest system eastward earlier. Overall, prefer a blend of the GEFS/NAEFS/ECMWF ensemble means, leaning a bit toward the 12 UTC GFS/UKMET early-mid next week over the Northwest and vicinity given flow amplitude and history. Farther south, applied manual adjustments to offset this blending process to ensure sufficient low pressure system depth on the WPC medium range pressure progs over the Gulf of Alaska given favorable upper support in all guidance. Overall, WPC product continuity is reasonably well maintained with this forecast plan. ...Weather/Hazards Highlights... The carving out of an amplified and slow moving closed upper trough and deepening surface based low over the Gulf of Alaska to the east of an anomalously amplified upper ridge will present a protracted maritime threat next week. Meanwhile, easterly waves rotating overtop from Southeast Alaska to Southcentral/Alaska Range and the southern Interior will support uncertainly timed daily bouts of mainly light to moderate rains across the broad region next week, but perhaps especially into locally favored terrain of the Southeast and the eastern Alaska Range. Further north, uncertain upper troughing over Northwest Alaska and the North Slope/Brooks Range may support some chances for locally unsettled weather and rain early next week. Increasing and more widespread activity may work into western and southwestern Alaska mid-later next week as there is a growing guidance signal to support the eastward approach of a modestly deep but potentially moist Bering Sea system set to round the northern periphery of the aforementioned upper ridge. Schichtel Hazards: No significant hazards are expected over Alaska during this forecast period. 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