Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 316 PM EDT Fri Oct 25 2019 Valid 12Z Tue Oct 29 2019 - 12Z Sat Nov 02 2019 ...Heavy coastal rain and mountain snow for southeastern coastal areas and much above normal temperatures for the central and northern mainland early next week... A highly amplified upper pattern will be in place at the start of the medium range period, with a strong closed low in the eastern Bering Sea and a well-defined ridge downstream from the panhandle northward through the Yukon. The amplified nature of the pattern will allow moisture from the subtropics to be transported northward, and where it impinges on the southeastern coast, there will be heavy rain and high elevations snows. In addition to the precipitation, the southerly flow will allow warmer than normal air mass to overspread the southeast and Panhandle. Starting Day 4, the models diverge in handling the closed low in the eastern Siberian Sea. The 00-12Z ECMWF shows the low and associated frontal boundary drifting east, while the 12z GFS and Canadian Global are slow to move the low. In fact, with the 12z GFS on the western fringe asna outlier solution, the 06z run was used as a blend with the more highly weighted ECMWF and ECMWF Ensemble Mean. An amplified upstream ridge would help to keep the closed circulation in place. The middle of next week sees the weakening Bering Sea closed low move onshore across southest AK and then further inland as it deamplifies. Given overall good agreement among the ECMWF Mean and 06z GFS, a blend of these solutions was used in conjunction with the operational ECMWF. During the middle to latter part of next week, a new circulation forms and moves south of the lower Aleutians Wed and middle Aleutians Thu. The 12z ECMWF trended west to match the prior ECMWF Ensemble Mean and 06z GFS, so a blend of these solutions was used due to better than average clustering. The 12z GFS was a faster/north outlier, thus not used in the overall blend. The low lingers in the Gulf of Ak Sat 02 Nov as it weakens. This system may bring a renewed outbreak of widespread precipitation for the southern coastal sections Thursday into Friday. Petersen 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 Alaska Hazards... 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