890 FXAK68 PAFC 241331 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 531 AM AKDT Sun Oct 24 2021 .ANALYSIS AND UPPER LEVELS... The upper levels feature a low over the southern Gulf with rather weak and chaotic flow over Southcentral and Southwest Alaska. A trough extends into the Kuskokwim Delta from the northwest, with ridging over much of the Bering. Another shortwave disturbance is over the Western Aleutians. The key feature is an intense 160 kt jet over the Central to Eastern Aleutians, which intensifies to 180 kt as it turns southeastward into the North Pacific south of the AKPEN. At the surface, a low is both weakening and rapidly shifting south of Kodiak this morning, with a wide area of cumulus over much of the Gulf this morning. A stronger low is moving towards the Panhandle. A shortwave disturbance is causing snow along the Talkeetnas and far western Copper River Basin. Rain shower activity stretches across the North Gulf Coast, southern Prince William Sound, and is moving over the Kenai Mountains, including Seward. Dry weather persists over Anchorage, the Mat Valley, and the western Kenai Peninsula. Outside of an isolated shower over Bristol Bay near Koliganek and New Stuyahok, much of Southwest Alaska is also dry, but under mainly cloudy skies. A large low is moving across the western Bering through the Central Aleutians, with unstable stratus developing from colder air moving southeastward from the Kuskokwim Delta to the AKPEN. && .MODEL DISCUSSION... The models are in excellent agreement through late Monday night. The models have struggled a bit with the timing of bringing colder air into southern Alaska, especially Southcentral by midweek, but overall quiet weather across the mainland, with a storm force low racing across the Aleutians are all being well handled by the models this morning. Forecast confidence is high. && .AVIATION... PANC...VFR conditions and light winds will persist. A shower or two may develop in the vicinity this morning. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Today through Monday night)... An area of low pressure southeast of Kodiak remains mostly stationary over the western Gulf this morning. Radar and satellite reveal some of the more subtle details associated with this feature, including a shortwave tracking northwest across the Copper Basin and ongoing light showers from Prince William Sound into the eastern slopes of the Kenai Peninsula. A tightened pressure gradient between these two lows is producing Small Craft winds offshore of the coast into Prince William Sound. Buoy 61 has reported gusts ranging from 25 to 33 knots during the overnight hours and these winds will likely persist through the first half of Sunday before tapering off Sunday afternoon and evening. A light rain/snow mix is occurring over the Talkeetnas and is expected to persist into the latter half of the day as the shortwave moving across the Copper Basin begins a northward jaunt into central Alaska. However, any snow accumulations should also remain light and confined to the higher elevations, leaving the main roads clear. Meanwhile, the Anchorage Bowl will see some clearing of clouds throughout the day on Sunday as the low over the gulf temporarily retreats southward and further away from the region, and the shortwave over the Copper Basin departs Southcentral completely by Monday. Partly cloudy to partly sunny will be the story of the day for inland portions of Southcentral into Monday with relatively warmer temperatures in the upper 30's and low to mid 40's. Further south, any lingering precipitation will be confined to the east half of the Kenai Peninsula and Kodiak Island. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2: Today through Monday night)... Cooler air will move across the region over the next couple of days as shortwaves rotating around an Arctic low north of the Bering Strait draw in cooler air. Lows will generally be in the 20s and highs in the 30s. The first shortwave will move across the area today producing areas of light rain and snow mainly across Bristol Bay where the most of the energy will be located. However, no significant accumulations of snow expected as most of the activity with be very light. Monday night another shortwave will bring a few snow showers to the Kuskokwim Delta. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2: Today through Monday night)... A ridge of high pressure across the eastern Bering and Aleutians this morning will give way to a storm force low moving along the Aleutian chain today and then moving south of the AKPEN and into the Gulf by Monday morning. This low will bring a good swath of gales and areas of storms near the Central Aleutians with areas of moderate to heavy rain. Behind this low a broad ridge with winds small craft or less is expected Monday and Monday night across much of the area. && .MARINE (Days 3 through 5: Tuesday through Thursday)... A well developed low in the central Gulf will reach the Gulf Coast on Wednesday and dissipate. Northwesterly gale force gap winds are likely through the Alaska Peninsula stretching to the Barren Islands until Wednesday morning. Seas to 18 feet south of Kodiak Island will diminish Wednesday. A low develops over the Bering by Tuesday afternoon and tracks over the Alaska Peninsula on Wednesday and will likely be located over Kodiak Island by Thursday morning. Forecast confidence is high for high end gales across the Bering from late Tuesday night until Thursday. Seas to 15 feet are likely across the central and southern Bering on Wednesday and will subside Thursday. A new low approaches the western Aleutians early Thursday morning. However, forecast confidence with this low is extremely low at this time. Some models indicate near storm force winds while others indicate small craft winds. This area of the forecast will continue to be refined over the next few days. && .Long Term Discussion (Days 4 through 7: Wednesday through Saturday)... Overall, there is decent model consensus through the end of the week and entering the weekend. Each solution is pointing towards a broad longwave trough pattern developing across Southern Alaska, including both the Bering Sea and the Gulf of Alaska. This pattern features a North Pacific low moving into the Gulf of Alaska by Wednesday, while a separate system moves southwards out of Russia across the Bering, both of which are expected to produce some form of precipitation for their respective areas. The chance for snow increases as elevation increases. The Gulf low moves onshore over Prince William Sound by Thursday and fizzles out, meanwhile, the Bering low crosses the Alaska Peninsula and into the Gulf. This is when model spread begins to grow. There are some timing issues as to when the low moves over Kodiak, but most solutions agree on turning to a northerly track moving up Cook Inlet. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...Storm Warning: 173-177. Gale Warning: 155, 170-172, 178, 411, 413. && $$ SYNOPSIS AND MODEL DISCUSSION...JPW SOUTHCENTRAL ALASKA...BL SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RC MARINE/LONG TERM...AF/KM