073 FXAK68 PAFC 061238 AFDAFCSouthcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 438 AM AKDT Sat Sep 6 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...
The forecast remains on track with rain returning today and tonight as a large Bering Sea low extends a front into southern mainland Alaska. The leading shortwave trough may be just enough to promote some light rain showers for the Anchorage and Matanuska Valley this morning as mid-level moisture begins to stream in with southwesterly flow. Low-level flow begins to intensify out of the south to southeast later today, leading to some downsloping which limits precipitation amounts in the lee of the coastal mountain ranges. A coastal ridge also develops as the front slowly pushes into the western Gulf. This will initiate typical southeasterly gap winds, including the Turnagain Arm, Knik River, and Copper River winds later this afternoon. Expect light, intermittent rain for inland locations, while 1 to 2 inches of rain is squeezed out along the north Gulf coast through Monday.
As the main surface front lifts across Southcentral on Sunday, weakening cross-barrier flow may limit downsloping and allow for a more sustained period of light rainfall for inland areas. Upper level support for the Bering low weakens as it progresses toward Southcentral. The surface low opens into a trough Sunday night through Monday. Thus, the potential for light rain showers will persist area-wide. Decreasing pressure in the Gulf of Alaska erodes the coastal ridge, however, leading to fairly calm winds for the beginning of next week.
Quesada/Rux
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.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS (Today through Tuesday Morning)...
The forecast remains on track at least in the near term through today. More about lingering uncertainty with a North Pacific low below...Starting with the current weather status, a large vertically stacked low continues to take up real estate in the central Bering Sea this morning west of the Pribilof Islands. The front it currently draped over mainland Southwest Alaska with strong gusty southeasterly winds across the Kuskokwim Delta coast. Along with the gusty southeasterly winds, higher wave heights and increased water levels are likely this morning along the northern Kuskokwim Bay coast including the communities of Kongiganak, Kwigillingok, and Kipnuk. Peak water levels (1 to 2 feet above the normal highest tide line) are expected late this morning before slowly subsiding during the afternoon hours. While significant coastal flooding is not expected, low-lying areas filling up with water is not out of the question. Wave heights of 4 to 8 feet within the coastal waters of the Kuskokwim Delta and along the coast will persist most of today before slowly subsiding tonight into Sunday morning. A Special Weather Statement remains out for the Kuskokwim Delta Coast/Northern Kuskokwim Bay Coast to bring further awareness to the water level rise, gusty southeast winds, elevated wave heights/surf, and impacts.
Elsewhere, showery conditions will continue across the Aleutians, Alaska Peninsula (AKPEN), and mainland Southwest for most of today. While the Western and Central Aleutians will see improving conditions as the day progresses due to a ridge building across the western Bering, mainland Southwest and the AKPEN remain showery through Monday. The Eastern Aleutians sees improvement by Sunday afternoon as the ridge across the Western and Central Aleutians moves east over the area.
Behind the developing ridge, a North Pacific low looks to track in close proximity to the Aleutian Chain Sunday evening through Tuesday morning. There is still uncertainty in exactly how close the low will track to the Chain. As of early this morning, guidance has come in stronger and shifted the track of the low a little bit further to the north and closer to the Aleutians, which would be a windier and rainier solution as opposed to a further south in the North Pacific/away from the Chain solution. However, guidance has been flipping back in forth between close the Aleutians and further away; thus the continued uncertainty. Continue to follow the latest forecast updates as details about this system become more clear with time.
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.LONG TERM FORECAST (Days 4 through 7 - Tuesday through Friday)...
Only minor changes from previous discussion... At the beginning of the week, a gale or potentially storm-force low is likely to be located near the central Aleutians. To the east, a trough extends south across Western Alaska into the Gulf of Alaska. Near and ahead of the trough axis, rain showers will be favored as a former surface low pressure system winds down and deposits its moisture across the state. The trough exits east into Yukon by Tuesday, with a quickly- progressing ridge moving in to replace it across southern mainland Alaska. As a result, rain showers diminish across the region. Along the Aleutians, it is difficult to pinpoint impacts from the potentially storm-force low, as there is significant uncertainty in the track. Regardless, expect periods of strong, gusty winds, potentially as strong as storm force. Accompanying the low will also be tropical moisture with precipitable water values of 1.5 inches or greater sourced from Tropical Storm Peipah (currently located over southwestern Japan) and strong dynamics which will lead to moderate to heavy rain along the Aleutians on Monday.
For Tuesday, the low tracks near or just south of the Aleutians toward the Alaska Peninsula and into the northern Gulf of Alaska. The occluding low begins to lose some of its moisture tap and strength, though its front, depending on track, may lift into the Southwest Alaska coast near gale force. This would lead to a low potential for some coastal flooding/erosion concerns on Tuesday, though a more southern track would negate this potential. Light to moderate rainfall begins to move inland over parts of Southwest Alaska, regardless of track. In general, the low appears stronger than the previous low, so winds and precipitation are expected to be greater than what is seen on Friday and Saturday.
The low tracks somewhere in the vicinity of Kodiak Island by Wednesday. Its front pushes east along the Gulf of Alaska coast, where it may cause moderate to heavy rain along the coastal mountains. The abundant moisture and weak to moderate cross- barrier flow likely allows for at least some rainfall to push past the coastal mountains into inland Southcentral at times. The low continues to shift slowly eastward toward the end of the week, keeping generally showery conditions in place across the southern mainland, with heavier rain along the coast. For the Bering Sea and Aleutians, surface high pressure moves in mid-week, though the upper-level pattern appears fairly messy and the confidence in any individual feature`s location is very low.
Quesada/DD
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.AVIATION...
PANC...A weak disturbance may bring a period of light rain and potentially lower ceilings to MVFR early this morning before lifting by mid-day. A Turnagain Arm wind is expected to develop this evening and persist through Sunday morning.
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NWS AFC Office Area Forecast Discussion