Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 700 PM EDT Wed Sep 11 2024 Valid 12Z Sun Sep 15 2024 - 12Z Thu Sep 19 2024 ...Bering Sea storm to bring heavy rain and coastal flooding/wind threats to West/Southwest to Interior Alaska this weekend... ...Guidance Evaluation/Preferences... Latest models and ensembles show highly energetic and progressive flow with a series of potent storms for Alaska and maritime interests A composite of reasonably clustered guidance of the 12 UTC GFS/ECMWF/UKMET/Canadian offers good detail consistent with improved to above normal system predictability and WPC product continuity into early next week despite some lingering timing differences averaged by the blend. Prefer the still compatible GEFS/ECMWF ensemble means at longer time frames amid steadily growing forecast spread and uncertainty. Manual adjustments ensure sufficiently strong surface systems given favorable upper support to offset weakening inherent to this blending process. ...Weather/Hazards Highlights... A potent low pressure system tracking across the northern Bering Sea during the weekend will slam inland to bring a threat of heavy rains and high winds/coastal flooding to western and especially southwest Alaska before working earnestly inland to affect the Interior and Brooks and Alaska Ranges. These threat are depicted on the WPC Day 3-7 Hazards Outlook. Energy will also quickly progress underneath and eastward to spread a swath of unsettled weather with and enhanced rains/winds/waves over the Gulf of Alaska and inland to southern to southeastern areas of the state in association with the storm's frontal system and triple point low pressure system development. By Monday, uncertain lingering low pressure over or near the northwestern mainland and shortwave energy aloft may support persistence of lighter precipitation. Confidence has risen to closer to average regarding the details of the next potential storm during the early-middle part of next week. Current guidance preference would bring the low track through the Aleutians and southern Bering Sea, then tracking near/offshore the Alaskan southern tier, eventually crossing Southeast Alaska. This would confine the majority of precipitation to the southwestern mainland and southern to southeastern Alaska. There is also a risk a enhanced to high winds/waves given system strength and speed. 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