Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 643 PM EST Sat Feb 25 2023 Valid 12Z Wed Mar 01 2023 - 12Z Sun Mar 05 2023 ...Heavy precipitation continues across the Panhandle into Wednesday... ...Overview... For the latter half of next week, a trough aloft and a couple of surface low pressure systems consolidating in the Gulf of Alaska will help produce heavy precipitation across the Panhandle, with Wednesday seeing the heaviest amounts. While precipitation types remain in question, it appears most areas over land should see snow, even over coastal areas of Southcentral Alaska into the Panhandle. Gusty to high winds are possible on the backside of the compact but possibly deep low, in favored gap wind areas of the Peninsula into Kodiak Island and the Kenai Peninsula along with the surrounding waters and islands. Then by next weekend, upper ridging looks to move into the Aleutians first and then set up across the mainland. This should cause initially colder than average temperatures to moderate and direct the storm track across the Aleutians and western Alaska. ...Model Guidance/Predictability Assessment... Model guidance shows reasonably good agreement today with the larger-scale features of the forecast. Models indicate that a surface low near or over western Alaska should weaken on Wednesday in favor of a triple point low forming over the Gulf of Alaska. Another low may reinforce the latter feature after it treks quickly from Bristol Bay across the Aleutians Thursday. Meanwhile the track/strength of a trough in the upper levels moving across the mainland is pretty agreeable in the guidance. Thus for the first half of the period, the WPC forecast was based on a blend of the deterministic 12Z ECMWF/GFS/CMC/UKMET, with the blending process serving to smooth out any small differences. Models also show fairly good consensus with an upper ridge building behind this trough, first across the Aleutians and Bering Sea and shifting into the mainland by the weekend, though with minor timing and amplitude differences well within reason of late medium range spread. Surface low differences become more of an issue next weekend within the trough to the west/aforementioned ridge though, but the overall signature for low pressure/fronts across the Aleutians and just west of Alaska is there. At this time ECMWF deterministic runs and many ensemble members are indicating a low atop or near the Aleutians by 12Z Saturday, while GFS and CMC runs are farther south at that point, and their ensembles show more spread. Incorporated gradually increasing amounts of the GEFS and EC ensemble means into the model blend to half by day 8 with the increasing uncertainty. ...Weather/Hazards Highlights... As the medium range period begins Wednesday, an upper trough, Gulf of Alaska surface low, and ample moisture will provide support for heavy precipitation. Most should fall across the Panhandle on Wednesday as precipitation over other portions of the state has phased into the short range period. Snow is currently forecast to be the primary precipitation type given the cold air in place. Precipitation could continue into the latter part of the workweek but amounts should gradually lessen. Northwest of the mean Gulf low, high winds are a concern around Wednesday-Friday across the Alaska Peninsula eastward into Kodiak Island and the Kenai Peninsula with strong offshore flow. A drying trend is likely across the Panhandle by the weekend as upper ridging moves into the mainland. Meanwhile western Alaska can expect more active conditions for next weekend as possible low pressure and frontal systems may affect the Aleutians into the western mainland. The details are still yet to be determined at this point though. Temperatures across the Panhandle are likely to be below normal in terms of highs for the latter part of next week, and lows and highs could continue to drop there into next weekend given northerly mean flow ahead of the upper ridge. Elsewhere, a somewhat progressive pattern will lead to some temperature swings. Wednesday should generally be near normal, but temperatures, particularly highs, will drop considerably across the mainland Thursday-Friday with the bout of upper troughing. By the weekend, at least the western part of the state is expected to moderate to above normal underneath the ridge. Tate 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