Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 311 PM EDT Sun Jul 28 2019 Valid 12Z Thu Aug 01 2019 - 12Z Mon Aug 05 2019 The flow pattern over Alaska during the medium range (Thurs-Mon) continues to look fairly progressive. This features an upper level low skirting the northern coast on Thursday before lifting north into the Arctic, which drives a front through northern and central interior Alaska. Meanwhile, one shortwave should be moving into the Gulf/North Pacific at that time, while better defined troughing moves into the western Bering. Models seem to be coming into better agreement on the idea of the Bering Sea system lifting towards the vicinity of the Bering Straight/northwestern Alaska by day 7-8. Upper level ridging dominates most of the period across southern Alaska and the Panhandle. This supports rain (and maybe higher elevation snows) across northern Alaska/north slope region, with the best chance for moderate to heavier activity along the favorable terrain. A couple of rounds of rain are likely across the Aleutians/Peninsula region as well as shortwave energy passes through on Thursday, and more amplified troughing takes shape across the Bering Sea next weekend. Expect additional rains across northern Alaska next weekend as the Bering Sea system moves towards the Bering Straight. In general, the 12z GFS/00z ECMWF show fairly good agreement days 4-5 (albeit some minor timing and amplitude differences) to warrant a majority deterministic blend for the first part of the period. After this, detail differences in the deterministic runs begin to emerge, especially with respect to the deep low across northern Alaska/the Arctic and the evolution of the second shortwave nearing the Bering Straight days 7-8. The ensemble means show good agreement through day 7, with some timing differences beginning to creep in by day 8. A blend of the GEFS mean with the ECENS mean seemed to provide a good starting point days 6-8, with smaller contributions from their respective deterministic models as well. The resulting forecast fits well with the previous WPC forecast, as well as with continuity downstream across the CONUS. Santorelli Additional 3-7 Day Hazard information can be found on the WPC medium range hazards 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