Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 605 PM EST Wed Dec 06 2023 Valid 12Z Sun Dec 10 2023 - 12Z Thu Dec 14 2023 ...Heavy Precipitation and High Wind Threat from SouthCentral/Alaska Range to Southeast Alaska... ...Guidance Evaluation/Preferences... Medium range models and ensembles now overall offer below normal forecast spread in this stormy pattern with seemingly better than average predictability and continuity, but vary with smaller scale system interactions. A preferred composite of best clustered guidance from the 12 UTC GFS/ECMWF/Canadian models and the GEFS/ECMWF ensemble means seems to mitigate these variances to offer a good forecast basis for at least the mid-larger scale pattern evolution and weather hazards. ...Weather/Hazards Highlights... An amplified upper trough forged over the southern mainland into this weekend will offer a period of cold temperatures. The unsettling upper trough position should linger next week over the mainland as reinforced by less certain shortwave energies. Meanwhile, a main storm genesis pattern will emerge just to the south of the state by early through mid next week with the development and poleward track across the Gulf of Alaska to the mainland of a series of complex and deepened low pressure/frontal systems as stream flows uncertainly interact. The systems will offer a maritime to coastal high wind/wave threat. Deep layered moisture will also feed inland by enhanced wind flow around these storms, with main focus over SouthCentral/Alaska Range through Southeast Alaska. Expect a multi-day period with periodic surges of heavy precipitation in the form of coastal rains with potential runoff issues to heavy inland terrain/mountain snows. Additionally, gusty terrain enhanced winds expected for this region that may lead into downslope Chinook winds to the lee of the Alaska Range down into the southern Interior next week. Schichtel 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