Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 PM EDT Sun Apr 07 2024 Valid 12Z Thu Apr 11 2024 - 12Z Mon Apr 15 2024 ...Storm system to bring moderate to locally heavy precipitation to Western Alaska with Maritime impacts... ...Synoptic Overview... An amplified trough over the Bering Sea will move through Mainland Alaska Friday and into the weekend bringing gusty winds, maritime impacts, and moderate to heavy precipitation. Additional shortwave energy may briefly close off another upper low in the Gulf this weekend, keeping conditions unsettled for Southeast Alaska. General weak troughing will be reinforced over Mainland Alaska into early next week as another system slides near/just south of the Aleutians and phases with a second stronger surface low lifting northward through the north Pacific. ...Guidance Evaluation and Preferences... The 12z model guidance today shows a good overall depiction of the synoptic scale pattern through about the first half of the period, and so a equal blend of the deterministic model solutions was used for days 4-6. The models today have clustered more towards an amplified trough moving through the Bering Sea and Mainland late this week/weekend. There remain some differences in the timing and details of the system, but higher confidence in some possibly impactful weather across the Western portion of the mainland. Shortwave energy rounding the base of the system should allow for brief surface low development in the Gulf, which looks to quickly translate eastward. The 12z CMC was an outlier with wanting to hold back energy or a closed low for longer across the Panhandle. Compared to yesterday, the guidance has also trended stronger with a compact system that slides south of the Aleutians this weekend with plenty of uncertainty in eventual phasing of this with a larger system lifting northward from around Hawaii early next week. For days 7-8, increased the ensemble mean usage in the blend, along with the ECMWF and GFS for some added system definition. ...Weather/Hazards Highlights... For Thursday-Friday, a system moving into the Mainland will bring possible heavy rain/mountain snows across parts of the West, along with gusty winds and maritime impacts. Farther South general troughing should keep the Southern Coast/Southeast/Panhandle generally unsettled much of the period as well. The West may dry out this weekend, but an additional cold front from the north may bring another round of rain/snow to parts of northwest Alaska Sunday-Monday. Temperatures across the southern half of the state should trend cooler into the weekend as the upper trough moves through, with the highest anomalies likely across the Southeast. Northern Alaska should stay warmer than normal the entire period, but moderating somewhat as additional shortwave energy slides through the region. Santorelli 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