Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 758 PM EDT Sun Apr 14 2024 Valid 12Z Thu Apr 18 2024 - 12Z Mon Apr 22 2024 ...Synoptic Overview, Guidance Evaluation, & Preferences... An amplified upper level flow pattern is forecast to be in place across the Alaska domain for the middle of the week, with a strong ridge axis extending northward to the Yukon Territory, and a broad upper low situated south of the Alaska Peninsula. Strong onshore flow directed towards the coast will produce heavy precipitation for southern coastal areas, and lighter rain farther inland. A second area of low pressure will likely develop over the same general area by the weekend as a shortwave approaches from the west. The 12Z model guidance suite features decent overall synoptic scale agreement across the Alaska domain for the beginning of the forecast period Thursday. Going into late Friday and the weekend, the CMC and the UKMET take the Gulf low farther to the south than the model and ensemble consensus. By Sunday and Monday, models diverge considerably across the North Pacific with subsequent surface low evolution, and forecast confidence is limited outside of the mainland by this time. The fronts/pressures forecast was based on mainly a CMC/GFS/ECMWF blend as a starting point on Thursday, and then tapering off the CMC for Friday and beyond. Increasing percentages of the GEFS and EC means were used going into next weekend and next Monday. ...Weather/Hazards Highlights... Coastal rain and mountain snow is expected to be locally heavy going into the second half of the work week from the southern AKpen to the Prince William Sound region as moist onshore flow increases ahead of the Pacific low off the coast. Strong winds over this region is expected to produce high waves and gusts over 40 mph at times, especially through coastal inlets. Light showers are possible farther inland across southern mainland Alaska. Temperatures are generally expected to be mild with readings in the mid 40s to upper 50s for highs across most Interior locations south of the Brooks Range, and generally 40-45 degrees near the southern coastal areas. A cooling trend is likely by next weekend as the upper ridge axis breaks down. The Brooks Range will be the demarcation for much colder conditions across the North Slope and extending to the Arctic Coast. 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