335 FXAK68 PAFC 051326 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 526 AM AKDT Sat Jul 5 2025 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today through Monday night)... In the upper levels, a Rex Block is in place across Alaska, with a ridge centered over northern Alaska and a low centered along and south of the Aleutians. The weather over Southcentral continues to be driven by flow around the perimeter of the ridge though that will change as we head through the weekend. Overnight, a few clouds and isolated showers moved out of the Yukon and across inland portions of Southcentral. Low clouds have set up shop along the north Gulf coast and Prince William Sound in a more stable airmass. In between, skies are mostly clear. Meanwhile, short-wave troughs rounding the front side of the upper level low are driving a surface occluded front northward toward Kodiak island and the western Gulf, leading to rain and strengthening easterly winds. Short-waves rounding the ridge across the Yukon will track westward across interior Southcentral today, initiating afternoon showers and thunderstorms. There has been some north-south spread in the models with where the bulk of convection sets up, largely due to subtle differences with how much influence the trough in the Gulf has on the flow. However, 06Z model guidance is in better agreement in depicting the bulk of convection over the northern Copper River Basin, Talkeetna Mountains, and northern Susitna Valley. Thus, it look like another dry day for the Kenai Peninsula, Anchorage, and southern Mat-Su - though a stray shower can`t be completely ruled out across the southern Mat-Su later today. The short-waves won`t completely exit until late tonight, so showers will likely keep going through the overnight hours for the Talkeetna Mountains and northern Susitna Valley. The trough to the south will struggle to lift northward toward Southcentral, keeping rain confined to Kodiak Island and the Gulf today. However, a classic East-West surface ridge will set up along the Gulf coast between the front in the Gulf and thermal trough inland. This will lead to strong and gusty southeasterly gap winds this afternoon and evening. Sunday will be a transition day as the ridge weakens to the north and the upper low shifts into the Gulf, with short-waves rotating northward toward Southcentral. Increased cloud cover will lead to somewhat more stable conditions inland, with much less convection expected. Steady rain will settle in along the north Gulf coast and Prince William Sound. Short-waves will then rotate northward into Southcentral Sunday night through Monday, though model guidance varies on the exact track of short-waves. Rain is likely ahead of the short-waves, especially from Prince William Sound to the Copper River Basin. The big question is how far west rain will make it, as the upper low in the Gulf will continue eastward toward Southeast Alaska, causing flow over Southcentral to shift toward northerly and change the direction of flow (and movement of short-waves). Stay tuned, as there is potential for widespread wetting rains to start the work week. Forecast confidence continues to fall Monday night into Tuesday as an Arctic trough digs southward across mainland Alaska. Model guidance continues to struggle with the ultimate track and amplitude of the Arctic trough, with individual short-waves leading to wildly different solutions among the guidance. The likely bet is that unsettled weather will persist as we continue through the work week. -SEB && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... Upper level high pressure remains centered over the northern Alaska coastline with the Beaufort Sea. A weakening low pressure system is centered in the eastern Bering, northwest of Unimak Island, with a front that extends southeast into the North Pacific. This front will continue to bring gusty wind and precipitation across the Alaska Peninsula and into Bristol Bay as it weakens through this afternoon. These two larger synoptic features (high and low pressure centers) will direct nearly zonal flow across the Alaskan interior through Sunday. Models are honing in on an upper level vorticity maximum, moving through Sunday morning, that will bring an increased chance of moderate rain showers and thunderstorm development westward across the Kuskokwim river valley and diving southwest across the Kuskokwim delta, before diminishing Sunday afternoon over Kuskokwim Bay. Model runs have progressively brought the track of this system southward, from over Nunivak Island to over Kuskokwim Bay. The GFS and ECMWF were previously holding onto a more northern track and are very incrementally coming into better alignment with the more southern track of the NAM/GEM. Drier conditions are expected on Monday and Tuesday for the Alaska Peninsula and Bristol Bay with the lingering potential for afternoon showers across more interior regions of the state. && .LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The long-term period begins with upper-level lows across the southeast Gulf of Alaska/Southeast mainland Alaska and over the Central Aleutians. Between these lows is a weak ridge across the Southcentral and Southwestern mainlands. Expect drier conditions towards the southern mainland coast on Tuesday with showers in the afternoon for the interior and along the interior terrain. Light rain moves across the Aleutian Chain from the Western Aleutians Tuesday to the southern Alaska Peninsula (AKPEN) through Wednesday evening in association with an eastward track North Pacific low. Showers continue across the southwestern interior and the northern Susitna Valley Tuesday and Wednesday as an Arctic trough digs southward. One trend from yesterday`s long-term forecast is that this Arctic trough does not look to dig as far south, but only as far south as the trough axis reaching Norton Sound. Therefore, do not expect temperatures to be way lower than normal but more slightly below normal for Southwest Alaska. Meanwhile, the North Pacific low that tracked from the Western Aleutians to the southern AKPEN looks to have its energy move to the Gulf by Thursday. There are still some questions about the exact track of the low and its timing. However, there is reasonable confidence to say that the Southcentral coast, including Kodiak Island, will be the wetter locations Thursday and Friday when compared to the interior locations. Back to the west, a Kamchatka system looks to move close the Western Aleutians by Friday bringing another chance for rain and gusty winds by then. &&.AVIATION... PANC...VFR conditions will persist. There is high confidence in strong gusty southeasterly winds developing this afternoon, with tightening pressure gradients ahead of a front lifting northward across the Gulf. Forecast pressure over the Susitna Valley will be weakly lower than Anchorage. As a result, the core of strongest Turnagain winds should stay south of the terminal. Still, with continued sunshine and a well mixed boundary layer, winds will be quite gusty. The only uncertainty is how high the wind gusts will get. Based on forecast soundings, 30 kts seems most likely, though there could be some isolated stronger gusts of around 35 kts. Winds will slowly diminish after 06Z as a surface low develops over the northwestern Gulf and the Turnagain jet bends southward. -SEB && $$