FXAK68 PAFC 040033 AAD AFDAFC Southcentral and Southwest Alaska Forecast Discussion...UPDATED National Weather Service Anchorage AK 333 PM AKST Tue Dec 3 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... Key Points: * Winter Weather Advisory for snow and freezing rain for Copper River Basin south of Glennallen until 9 AM AKST Wednesday * Winter Weather Advisory for freezing rain for the Susitna Valley until 3 AM AKST Thursday * Winter Weather Advisory for blowing snow for Thompson Pass in effect until midnight Tuesday night * Strong winds and heavy precipitation along Southcentral coast, with gale to locally storm-force winds in the northern Gulf, Cook Inlet, and Shelikof Strait through Wednesday Discussion: Southerly upper-level flow with multiple shortwaves and lows embedded within it continues into Southcentral, keeping the weather pattern active and bringing more strong winds and precipitation mainly along the coast. A strong low continues north-northwestward near Kodiak Island through tonight. The front will push inland this evening, but gale-force Cook Inlet and Shelikof Strait winds will continue through Tuesday night. Winds may approach storm-force, especially near the Barren Islands. Steady upslope precipitation, in the form of rain at sea level, will continue through at least Wednesday as reinforcing waves stream up from the south. Typical downsloping areas should now remain mostly dry through most of tomorrow, but periods of light freezing rain are expected to continue across the Susitna Valley through 3AM Thursday. Additionally, periods of snow and freezing rain mix are expected to continue across the southern Copper River Basin, particularly south of Glennallen, through Wednesday morning where a Winter Weather Advisory is in effect. By late Wednesday evening into Thursday night, an additional shortwave trough will swing in from the south. This will likely weaken the downsloping effect across the western Kenai northward through Anchorage and the Mat-Su Valley, allowing some additional precipitation to fill in and spill over the mountains through Thursday morning. With temperatures hovering right around freezing, another period of freezing rain is possible, although confidence remains low at this time. Eovino && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3: This afternoon through Friday evening)... MAIN POINTS: * Winter Weather Advisories for freezing rain are in effect through Wednesday evening / Thursday afternoon across Bristol Bay and the Lower Kuskokwim Valley. * Warmer air moves into Southwest Alaska this evening through Wednesday afternoon. * Periods of rain and snow showers continue through Friday in the Aleutians. The forecast remains on track for the most part. The biggest change was to drop the Winter Weather Advisory for freezing rain across the Kuskokwim Delta due to the area being colder than originally thought. There could still be a few observations of freezing rain Wednesday, especially south of Bethel, but for the most part, freezing rain is no longer a main concern there. Elsewhere across Southwest, portions of Bristol Bay such as King Salmon, Dillingham, and Igiugig have already recorded freezing rain today. This trend will continue tonight through early Wednesday evening with multiple rounds of light precipitation move across the area as warmer air aloft overrides cold air at the surface. The highest likelihood for ice accumulation will occur along a line roughly from Dillingham northward to Koliganek. A Winter Weather Advisory remains out for Bristol Bay until 5PM AKST Wednesday. Meanwhile, a Winter Weather Advisory also remains out for the Lower Kuskokwim Valley. However, the start time has been moved back to 9PM AKST this evening when the first wave of moisture is expected to arrive. This advisory remains out until 4PM AKST Thursday as multiple rounds of precipitation are expected. Precipitation-type could fluctuate back and forth between snow and freezing rain with each round of moisture. Beyond Thursday, conditions remain unsettled and showery across Southwest Alaska as cold air works back in for Friday. Farther out west, scattered rain and snow showers continue across the Aleutians and the Alaska Peninsula through Friday. However, the Western Aleutians could see a break Thursday as a shortwave ridge moves overhead with activity being more focused along the Central and Eastern Aleutians. Another trough approaches the Western Aleutians late Thursday night into the day on Friday with more rain and showers likely. && .LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)... A closed upper level low exits the Southeastern Gulf Saturday. High pressure extends across Interior Alaska through Tuesday. Over the Bering, conditions become less chaotic as a closed North Pacific low begins its track along the Aleutians and dissipates South of the Alaska Peninsula late Sunday. Deterministic model blends carry the features through Sunday, with the ECMWF and Canadian means picking up the tracks and strengths through the end of the forecast period. The overall pattern becomes less busy as the number of shortwaves is reduced. An elongated West-East trough takes up across the Bering through Tuesday. On the surface, a lingering closed low near Prince William Sound adds moderate rain to the coastal areas with some snow further inland Saturday. A North Pacific low closes in on the Central Aleutians, brings some areas of snow before changing to widespread moderate rain. Snow moves into the Bering and Southwest Alaska, while the rain pushes over the AKPEN and Kodiak Island through Sunday. The rain continues along the Southcentral coast, with areas of moderate to heavy rain over Kodiak Island and the Kenai Peninsula Monday, spreading over Prince William Sound and the rest of Southcentral coast through Tuesday. Areas of snow extend towards the Alaska Range, with mixed precipitation possible over the Chugach Mountains. && .AVIATION... PANC...A strong upper level short-wave will track onshore of Southcentral late this afternoon through early evening, leading to strengthening southeasterly downslope flow. This will cut off any remaining freezing rain at and near the terminal. This flow will persist through the day Wednesday, maintaining VFR ceilings. The wind forecast is a little trickier. A deep low near Kodiak Island will weaken and track toward Bristol Bay. This will weaken down-Inlet pressure gradients while the Turnagain jet strengthens. Lower pressure will remain to the south, so think the Turnagain jet will largely remain just south of terminal, centered over Fire Island. This will likely lead to a period of low level wind shear. Cannot completely rule out a brief period of gusty southeasterlies at the terminal sometime late tonight through Wednesday morning, but if it does occur it would be short-lived. && $$