Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 412 PM EST Sat Dec 07 2024 Valid 12Z Wed Dec 11 2024 - 12Z Sun Dec 15 2024 ...Heavy precipitation along the southern coast through early next week... ...Storm-force winds possible near the northern Alaska coast and Gulf of Alaska coastline... ...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 to cause its erosion. Within the west-to-east trough, the main deep layer lows are expected to be most persistent over portions of the Sea of Okhotsk/Bering Sea and Gulf of AK/northeast Pacific, anchoring troughs on either side of the Pacific. While the broad flow is agreeable, detail issues remain with individual cyclones and 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... Deep south to southeast flow should keep south-central AK and Kodiak Island quite wet early, within 5-10" of liquid equivalent/rain expected mid next week, before rainfall/precipitation becomes less intense and moves eastward as the Gulf of AK portion of the trough slowly edges east, making the AK Panhandle wet, but not abnormally so. A cyclone early on could lead to storm-force winds near the Gulf of AK coast mid next week. 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 next week, with outflow/gap winds expected through the usual spots of Southeast AK/the AK Panhandle from next Friday into next weekend behind the arctic front. With a stronger arctic high expected to build over the Arctic Ocean and slip southeast, the threat of storm-force winds along the northern AK coast is increasing. This has also caused a cooling and clearing trend for northeast AK when compared to yesterday's forecast. A new cyclone approaching the Aleutians from the southwest next weekend looks strong enough, even with uncertainty factored in, to bring a risk of storm-force winds to the Aleutians and portions of the Bering Sea; at this range, the guidance can be too strong and sometimes too far north with cyclones, so the forecast bears watching as we get closer to next weekend. The general upper troughing near southern AK and the Bering Sea should keep sea level pressure near to below average statewide. The stormy pattern should offer gales near most coasts and island groups. 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