Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 718 PM EDT Fri Aug 30 2024 Valid 12Z Tue Sep 3 2024 - 12Z Sat Sep 7 2024 ...Guidance Evaluation/Preferences... The 12Z model guidance suite has trended stronger overall with the expected Gulf low for the Tuesday-Thursday time period, and also farther west with the low track, compared to the model guidance from yesterday. The ECMWF is the strongest solution and this also has support from the AIFS guidance, whereas the GFS based guidance is generally a little weaker, but overall model spread has decreased compared to this time yesterday. Meanwhile, there has been a general weaker trend with the next incoming Bering Sea low for mid to late week, and there is some indication that these two low pressure systems could merge into a broader scale upper level trough/surface low by the end of the week. Model spread increases substantially across the Aleutians and the Bering by next Saturday, and the ensemble means were increased to about half by that time. ...Weather/Hazards Highlights... An intensifying low pressure system over the southern Gulf Tuesday is forecast to steadily lift northeast and approach the southern mainland Alaska coast by late Thursday, albeit weakening by that time. This will tend to keep conditions unsettled from the Alaska Peninsula to the Chugach Mountains and the Prince William Sound region, where moist onshore flow oriented orthogonal to the terrain will enhance rainfall, perhaps 4-8 inches of total QPF through Friday across the favored terrain. The overall trend has been for heavier rainfall totals compared to earlier forecasts for those areas, and a decrease in rainfall for the Southeast Panhandle region. Gale force winds are becoming more likely for the coastal and offshore waters as the low approaches, and may lead to higher tides. The incoming low pressure system across the Bering may also result in periods of rain for western mainland Alaska going into the middle of the week, accompanied by some stronger winds near the coast, but generally less intense than what was expected yesterday. This is where forecast uncertainty is greater and thus subject to additional changes going forward. In terms of temperatures, readings should be slightly above normal north of the Brooks and for much of the Interior, and near normal for 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