Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 349 PM EDT Sat Jul 20 2019 Valid 12Z Wed Jul 24 2019 - 12Z Sun Jul 28 2019 Trough/ridge pattern will only slowly shift eastward late next week through the weekend as a Gulf upper low fills. The models/ensembles remain in good agreement to start the forecast but then diverge from Friday onward. Preferred to stay closer to continuity rather than introduce a change while confidence is low. The 12Z GFS and 00Z ECMWF offered reasonable clustering with their ensemble means and each other to use as a starting point. This takes a northeast Pacific system toward the Panhandle Wed-Fri (good agreement here) with continued (but not continuous) rainfall. Upstream, a system will push through the Bering and reach the western coast of Alaska where it may either lift northeastward (12Z GFS) or have its southern extent (sfc wave) move across the AKPen into the Gulf (00Z ECMWF and somewhat the 06Z GFS) or get left behind in the Bering (00Z GFS, not too likely). Ensembles suggest somewhat of split, with the lead weakening low lifting northeastward but the trailing low becoming the deeper feature as it slides into the west side of the Gulf upper low. Given the uncertainty, opted to side with continuity and the 00Z ECMWF until a more meaningful ensemble signal emerges. Fracasso 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