Alaska Extended Forecast Discussion National Weather Service College Park MD 704 PM EDT Fri May 30 2025 Valid 12Z Tue 03 Jun 2025 - 12Z Sat 07 Jun 2025 ...Heavy rain and strong winds will impact portions of the Alaska Peninsula and Southwest and Southcentral Alaska into early next week... ...Overview... A consolidated upper low centered over the Bering Sea/eastern Aleutians to start the period on Tuesday will be relatively deep for early June. This will support a modestly deep surface low into southwest Alaska Mainland on Tuesday which should weaken fairly quickly. Another low will lift northward towards the Gulf into Wednesday continuing strong onshore flow to fuel moderate to heavy rainfall across the southern Coast and Panhandle regions, with some gusty winds. After mid-week, the guidance supports mean troughing over western Alaska, with ridging building over the Panhandle and eastern Mainland. Weak shortwaves will rotate south of the main trough axis, keeping most systems well south of the Aleutians and conditions over much of Alaska relatively stable. Another surface low may lift into the Gulf late next week, with another round of precipitation possible for the Southeast. ...Guidance Evaluation/Preferences... The latest guidance shows reasonable agreement through much of the period but plenty of uncertainty in the details of individual lows. The guidance shows the main low moving quickly into southwest Alaska the beginning of the period, but there remains some question on additional energy rotating across the Peninsula towards the southern Coast, and another weaker surface low lifting up towards the Gulf. The Canadian and to some extent the UKMET are on the faster side of the guidance with this low, and the GFS is strongest, all of which has implications for heavy rainfall across the Southeast/Panhandle region. Behind this, later next week, another surface low looks to lift north towards the Peninsula/Gulf region, but with much more uncertainty in the track. WPCs forecast for today used a blend of the deterministic models the first half of the period, transitioning to half ensemble means by the second half. ...Weather/Hazards Highlights... The ample moisture streaming into parts of southern Alaska in the form of a weak to moderate atmospheric river will produce areas of rainfall that could be heavy across the Alaska Peninsula and north toward the Kuskokwim Delta, spreading eastward into the favored terrain of Southcentral Alaska early next week. Light to moderate precipitation is likely to expand north into the Interior and perhaps reach the Brooks Range at times. Some higher elevation precipitation would be snow in the higher elevations. Modest rain is forecast to remain over the southern half of Alaska as next week continues, while the upper low gradually weakens over the Mainland. Light rain may reach Southeast Alaska by Monday, and moderate to perhaps locally heavy rain could occur in Southeast Alaska around midweek depending on the timing of lows. Gusty winds may accompany these systems as well. High temperatures near and under the primary upper low are likely to be cooler than average, covering southern Alaska next week. Lows are expected to be closer to average. The Seward Peninsula to the western and possibly central Interior will be the main area of above normal temperatures in the southerly flow just ahead of the upper low, especially early next week before moderating. The North Slope should also see colder than normal temperatures under the influence of an Arctic high. 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