Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 755 PM EDT Wed Sep 28 2022 Valid 12Z Sun Oct 02 2022 - 12Z Thu Oct 06 2022 ...Overview... A low comprised of energy that was once Kulap in the western Pacific will continue to weaken as it crosses the western Alaska Peninsula Sunday and settles in the Gulf of Alaska early next week. As it taps into Pacific moisture, enhanced precipitation is likely from Southcentral Alaska into the northern part of the Panhandle. Then attention will turn to another low pressure system crossing the Aleutians Monday and tracking across the northern Pacific midweek. Northern stream troughing may push toward the northwestern mainland by Wed-Thu. ...Guidance/Predictability Assessment... Model agreement for the 12Z cycle seems reasonable as the period begins, with the initial surface and upper low showing good agreement from the GFS/ECMWF/CMC runs just north of the Aleutians/AK Peninsula 12Z Sun. The main outlier was the UKMET, which was displaced north of consensus, so utilized a blend of the other deterministic models with a bit of GEFS and EC ensemble means as well early in the period. Temporary ridging is expected for interior Alaska Mon-Tue north of this feature and east of additional upstream troughing. A trough/likely closed low and an associated surface frontal system in the midlatitudes shows fairly good agreement just north of the Aleutians over the Bering Sea Mon, but models diverge quite a bit with the details of placement and orientation as the features dive southeast and then east across the eastern Pacific Tue and beyond, with no clearly favored model. Additionally, a spoke of Arctic troughing could reach especially northwestern Alaska mid to late week, though with considerable timing differences, and the ECMWF and EC ensemble mean are more flat than other guidance. Given the increasing model differences in both the midlatitudes and Arctic, the WPC forecast gradually increased the GEFS and EC ensemble mean guidance weighting to 75 percent of the blend by the end of the period. ...Weather/Hazards Highlights... The initial low pressure system from Kulap's energy is forecast to progress into the Gulf early next week, which combined with Pacific moisture streaming in could lead to modest to potentially heavy precipitation (higher elevation snow and lower elevation rain) from the Kenai Peninsula eastward into Southcentral and especially northern parts of the Panhandle, which should linger there for a few days. Light showers, possibly in the form of snow, are also possible across parts of Interior Alaska particularly on Sunday and then again later in the week when Arctic troughing may approach. The details of the second surface low will impact the amount of precipitation across the Aleutians and possibly farther east for the first half of next week, so this will continue to be monitored. The bulk of Alaska will see low temperatures above normal through the medium range period, with more of a mix for highs. Above average highs are likely to be seen across the interior between the Brooks and Alaska Ranges, with pockets of below average within those ranges and for the southern part of the state through early next week. These areas, particularly the North Slope, are forecast to warm to above normal by midweek. Tate Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Oct 2-Oct 3. - High winds across portions of the Aleutians, Sat, Oct 1. 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