Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 407 PM EST Sun Dec 08 2024 Valid 12Z Thu Dec 12 2024 - 12Z Mon Dec 16 2024 ...Moderate to heavy snow possible for interior central/eastern 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 lows are expected to be most persistent from the Bering Sea westward and over the Gulf of AK/northeast Pacific, anchoring troughs on either side of the Pacific. There are fewer detail issues today, though those which persist involve how much upper level troughing is expected across Alaska itself. 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... Moderate to heavy rainfall/precipitation moves eastward as the Gulf of AK Wednesday into Thursday particularly across portions of the AK Panhandle, but nothing especially abnormal. Portions of southern and central 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 next weekend behind the arctic front. Also, moderate to heavy overrunning snows are possible across portions of central and eastern interior AK after frontal passage from late Thursday through Friday. With the arctic high continuing to trend stronger on the manual progs over the Arctic Ocean which slip southeast, the threat of storm-force winds along the northern AK coast has increased, 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. The general upper troughing near southern AK and the Bering Sea should keep sea level pressure near to below average statewide. 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