Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 653 PM EST Fri Mar 8 2024 Valid 12Z Tue Mar 12 2024 - 12Z Sat Mar 16 2024 ...General Overview... Much colder temperatures will already be in place across parts of northern and west/southwest Mainland/Interior, and will begin to slowly moderate by the later part of the forecast period. Multiple low pressure systems will track south of the Aleutians and into the northern Gulf, keeping precipitation focused across the Southern Coast, Southeast Alaska, and adjacent coastal mountain ranges. ...Guidance Evaluation and Preferences... The 12Z model guidance suite is in good overall agreement across mainland Alaska, but noteworthy differences are already apparent with the low pressure system tracking south of the Aleutians even by Day 4 (Tuesday). The main difference is with the GFS and to a lesser extent with the GEFS mean, indicating this low well to the northwest of the non-NCEP model consensus, and the GFS also becomes much stronger with the triple point low that forms over the southern Gulf by Wednesday. The machine learning guidance suggests a non-GFS solution for this time period, so no GFS was used through Wednesday. However, the GFS became more in line with the model consensus going into the end of the week, so it was brought back into the forecast blend for the Thursday through Saturday time period. Given increasing uncertainty in subsequent surface low evolutions across the North Pacific, the ensemble means accounted for about half of the forecast blend by next Saturday. ...Weather/Hazards Highlights... Most of Southeast Alaska and portions of the southern coast will be in an active and unsettled pattern through the extended forecast period as a few surface lows and frontal systems affect the region. Precipitation (rain and mountain snow) should extend back into the Southeast Coast/AK Peninsula and portions of the mainland under general unsettled flow/troughing, but not as heavy. Multiple systems maintaining rain across this part of the region coinciding with a warm up in temperatures across the Southeast may lead to snow melt, increasing the potential for runoff across the Panhandle where overall expected QPF has trended higher since yesterday's forecast. The period with the best potential for moderate/heavy rain will be Wednesday into Thursday, and also late Friday into Saturday. The Aleutians should stay wet and unsettled for much of the forecast period as several systems move through the region. There may also be some strong gap winds for the usual coastal locations at times. Temperatures for a vast portion of western Alaska will be quite cold into the first half 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 perhaps some -30s across the normally colder locations of the North Slope for the middle of the week. Hamrick/Campbell 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