Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 752 PM EDT Sun Mar 10 2024 Valid 12Z Thu Mar 14 2024 - 12Z Mon Mar 18 2024 ...General Overview... An amplified upper level flow pattern is expected to be in place across the Alaska domain for the second half of the week and extending into next weekend. A persistent upper trough over the western half of the mainland will equate to below average temperatures for the end of the week, but the trough should gradually weaken with slowly moderating temperatures going into the weekend. Meanwhile, an elongated upper ridge axis with developing closed higher over eastern Siberia, and a building ridge axis over western Canada, will tend to result in a rather blocky pattern that keeps the northwestern Alaska upper trough in place. A few surface lows will track eastward towards the Gulf region and produce rounds of unsettled weather from the Alaska Peninsula to the southeast Panhandle. ...Guidance Evaluation and Preferences... The 12Z model guidance suite features decent overall agreement among the GFS/ECMWF and their ensemble means through most of the forecast period. One of the exceptions is the 12Z CMC that is farther east with the trough over the mainland and suppresses the western Canada ridge much more than the model consensus, even by Friday. The UKMET was closer to the EC/GFS consensus, so this was used through early Saturday along with the GFS/ECMWF, and none of the CMC owing to its differences with the synoptic scale pattern. Given increasing uncertainty in subsequent surface low evolutions across the North Pacific and Gulf, the ensemble means accounted for about half of the forecast blend by next weekend. ...Weather/Hazards Highlights... Multiple rounds of moderate to heavy rain and mountain snow are expected from the eastern mountains of the Alaska Peninsula to the southeast Panhandle during the extended forecast period. A potential atmospheric event Wednesday night into Thursday for the Panhandle could bring a few inches of liquid equivalent precipitation by Thursday evening. The period with the second round of moderate/heavy rain and snow will be Friday afternoon into Saturday from the Kenai Peninsula to the St. Elias Mountains. There may also be some strong gap winds for the usual coastal locations at times. Temperatures for a vast portion of western and especially northern Alaska will be quite cold for the middle to end of the week, and thus well below average for early/mid March. Widespread subzero lows are expected for western and northern portions of the mainland, with widespread -10s and -20s across the North Slope for the middle to end of the week. Milder conditions will be expected by Sunday and Monday as highs rebound back into the 10s and 20s for most Interior locations, and 30s to low 40s near the southern coastal areas. Hamrick 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