Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 355 PM EST Mon Dec 09 2024 Valid 12Z Fri Dec 13 2024 - 12Z Tue Dec 17 2024 ...Moderate to heavy snow possible for interior southeast Alaska late Thursday & Friday... ...Storm-force winds near the northern Alaska coast, the Bering Sea, and the Aleutians at times; hurricane-force winds possible... ...Overview/Guidance Evaluation/Preferences... Model guidance remains consistent and agreeable in showing a mid- to upper-level ridge across mainland Alaska weakening as a trough between the Sea of Okhotsk and the Gulf of AK team up with a retrograding system across northern Canada into eastern AK to cause its erosion. Within the west-to-east trough, the main deep layer low is expected to be most persistent from the Bering Sea westward. Some detail issues remain, though those which persist involve how much upper level troughing is expected across Alaska itself and whether or not a cyclone moves into the AK Peninsula/southeast Bering Sea this weekend. For the pressures, fronts, winds, and QPF/PoPs, used primarily a compromise of the 12z runs of the GFS, ECMWF, UKMET, and Canadian before including some 00z ECMWF/12z NAEFS means later in the forecast to account for the uncertainty. The remainder of the grids were more 19z NBM heavy, as usual. ...Weather/Hazards Highlights... Rainfall/precipitation is expected to be relatively persistent near the southern AK coast, with an uptick in intensity becoming evident from this weekend into early next week from the Kenai Peninsula westward into portions of the AK Peninsula. Portions of southern AK should be relatively mild early, but the beating down of the mid- to upper-level ridge and the subsequent deeper layer flow becoming more northwesterly should cause the arctic drape/colder air to shift south into the far northern Gulf of AK by late week, with outflow/gap winds expected through the usual spots of Southeast AK/the AK Panhandle from Friday onward behind the arctic front. Also, moderate to heavy overrunning snows are possible across portions of interior southeast AK after frontal passage from late Thursday through Friday. With the arctic high over the Arctic Ocean early on, which slips southeast, the threat of storm-force winds along the northern AK remains, particularly mid to late week. Two new cyclones move near the Aleutians towards or into the Bering Sea late Thursday/Friday and again next weekend, expected to being storm-force winds to the Aleutians and portions of the Bering Sea with a threat of hurricane-force winds from the storm next weekend; the forecast bears watching as we get closer to the event to see if the guidance remains this deep with the cyclone and/or shifts its track northward into the southern Bering Sea. The general upper troughing near the southern Bering Sea/Aleutians should keep sea level pressure below average from late this week into early next week. Roth 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