319 FXAK68 PAFC 131302 AFDAFCSouthcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 502 AM AKDT Sat Sep 13 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Saturday through Monday Night)...
The surface low in the Gulf has finally dissipated early this morning and the last of the upper level low is exiting the Susitna Valley to the northwest this morning. This has been a very interesting system in that it was a former typhoon (Peipah) that went extra-tropical and then slowly weakened in place for days in the northwestern Gulf of Alaska. This remained stationary due to upper level support detaching from the system days ago and leaving it to push into the first strong cold front of the season which moved through Southwest Alaska, stalling along the Alaska Range. This kept Southcentral under a very moist airmass in the area of lift ahead of the front. If this setup occurred two months from now it may have dropped enough snow to strain snow removal for everyone. However, it fell as rain except for at higher elevations as it is only the middle of September. While there were impressive rainfall values in the eastern Kenai Peninsula and Prince William Sound with locations generally ranging from 3 inches to 8.5 inches for their 3 day totals as that region in vulnerable to that persistent southeasterly flow. However, with the upper level support well to the east, there was no atmospheric river to continually pump copious amounts of moisture, limiting the rainfall to mostly what was already part of the once- tropical airmass.
Even with the system departing the area this morning, it does not necessarily mean dry weather is here. There is a short wave just southeast of Prince William Sound embedded in the southerly flow. The associated rain showers can be seen on Middleton Island radar and these showers will slowly move northwest throughout the day bringing more rain to the Prince William Sound region, though they are not part of the former tropical system. It looks increasingly likely that these showers will curve more westerly into the evening and perhaps bring a fresh round of rainfall to the western Kenai, Anchorage, and the Mat-Su this evening into overnight tonight, though amounts are not expected to be very much.
The next big weather-maker tracks to the southern Gulf Sunday morning as a strong North Pacific low sends its front northward. This will bring in wet and windy conditions across Kodiak Island Sunday evening and coastal Southcentral on Monday. The low itself moves into the southern Gulf Monday morning as the front makes it to the northern Gulf Coast by then. As the front approaches the northern Gulf Coast, winds will be enhanced with a corridor of storm-force winds south and west of Kayak Island Monday morning. Northeasterly gales will also be likely through southern Cook Inlet, Shelikof Strait, and along the coastal waters of the eastern Kenai Peninsula.
Expect moderate to heavy rain to accompany the front along the coast as it traverses that area Sunday evening through Monday. Anchorage and most of the western Kenai Peninsula will see light rain at times Monday afternoon and evening with strong downsloping in easterly flow present at the 850 mb level. However, from Ninilchik south, steadier light rain is more likely with better moisture and lift. Most rain Sunday evening through Monday looks to fall along the northern Gulf Coast, Prince William Sound, and Kodiak Island. Between Sunday afternoon and Monday evening, portions of Kodiak Island, including Kodiak City, have the potential to 2 to 2.5 inches of rain in around a 24-hour period.
&& .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)...
Light rain showers are possible across the central Bering Sea/Aleutians as various weak surface lows embedded within a broad longwave trough continue slowly trekking eastward. Offshore flow and mostly clear to partly cloudy skies continue across Southwest Alaska, allowing for another night of temperatures in the 30`s, with some areas dropping below freezing. Precipitation is expected to continue to be negligible across Southwest Alaska through this weekend.
A North Pacific low travels well south of the Aleutian Chain towards the Gulf of Alaska, reaching the southern Gulf by Sunday afternoon. An area of small craft to gale force winds is expected south of the Alaska Peninsula Sunday, as well as northerly flow through gaps and passes of the southern Alaska Peninsula and Eastern Aleutians.
Early next week, a strong front looks to push into the western Bering Sea ahead of a low dropping south from Kamchatka. There remains some uncertainty about the strength of the low, with high end gales likely and a chance for a corridor of storm force winds. Additionally, a widespread band of precipitation is expected along the frontal boundary.
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.LONG TERM FORECAST (Tuesday through Friday)...
The active pattern continues in the long term with the main story being a pair of lows bringing wind and rain from the Aleutians to much of the mainland. Models are in fairly good agreement with the main feature to begin the period as a large 980-990 mb surface low continues to lift north into the Gulf early in the week. This system looks likely to peak in intensity Tuesday morning as it enters the southwestern Gulf. Heavy rain is expected along the eastern Kenai Peninsula and northern Gulf coast into Tuesday as the frontal system reaches the coast. Gusty northerly winds across the Alaska Peninsula enhanced by cold air advection on the backside of the low as well as the potential development of a gale-force barrier jet outside of Prince William Sound ahead of the front remain possible from the beginning of the period through Tuesday afternoon.
Farther west, a series of shortwaves emerging from the Kamchatka region and North Pacific look to merge as they enter the western Bering, shifting the axis of the longwave trough to a more positive tilt over the Bering. This becomes the dominant feature in the latter half of the long term as the decaying system in the Gulf gets absorbed, forming a large upper level low lifting from the North Pacific towards Bristol Bay. This system reaches the western Aleutians by early Tuesday and tracks along and just to the south of the Aleutian Chain and Alaska Peninsula, spreading rainfall and elevated winds west to east across the Aleutians and AKPen from Tuesday through Wednesday. Model spread and uncertainty in the eastward extent of the track remains high at this time, but expect rain to spread into Southwest Alaska as the low lifts towards Bristol Bay as the front shifts east and brings another round of rain to the Gulf late next week.
&& .AVIATION...
PANC...Light northerly winds are expected to persist. MVFR conditions are expected to improve to VFR through most of the forecast period. MVFR ceilings possible after 06Z Sunday.
&&
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NWS AFC Office Area Forecast Discussion