Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 542 PM EDT Fri May 31 2024 Valid 12Z Tue Jun 04 2024 - 12Z Sat Jun 08 2024 ...Southern Mainland/Interior to Southeast Alaska Heavy Precipitation Threat Tuesday/Wednesday... ...Guidance Evaluation and Preferences... Favor a composite of well clustered 12 UTC GFS/ECMWF/Canadian model solutions valid for Tuesday-Thursday in a pattern now with seemingly above average predictability and detail. Opted to switch preference to still quite compatible, but less detailed, 12 UTC GEFS/ECMWF/Canadian ensemble means for Days 7/8 amid gradually growing forecast spread, but especially with flow embedded surface lows offshore over the Gulf of Alaska. ...Weather/Hazards Highlights... A dynamic/closed upper low tracking to the south of Alaska will lift into the eastern/northern Gulf of Alaska into Tuesday-Wednesday. This will support a deepened surface low/system in the Gulf of Alaska and a period of heavy precipitation and high winds into Southeast Alaska given some enhanced ex-tropical moisture influx. Easterly wrapping flow and impulses offer an additional threat of heavy precipitation into eastern SouthCentral/Alaska Range along with some enhanced rains to the lee up into the Interior next week. Meanwhile, an upper low in the Arctic Ocean to the northwest of the state looks to send upper low/trough energy southward into the Bering Sea/West Coast and southeastward where there is growing support for a deepened upper low/surface lows later next week, while several weaker shortwaves traverse the southern side of this mean troughing south of the Aleutians and towards the Gulf. Over the Mainland itself, upper ridging should build warming. 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