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PKZ752 Castle Cape To Cape Tolstoi Out To 15 Nm- 341 Am Akst Wed Dec 6 2023
.small craft advisory through Thursday...
Today..W wind 25 kt. Seas 4 ft.
Tonight..W wind 30 kt. Seas 6 ft.
Thu..NW wind 30 kt. Seas 6 ft.
Thu night..W wind 25 kt. Seas 3 ft.
Fri..W wind 25 kt. Seas 3 ft.
Sat..W wind 15 kt. Seas 4 ft.
Sun..N wind 30 kt. Seas 10 ft.

PKZ700
No data

FXAK68 PAFC 061421 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 521 AM AKST Wed Dec 6 2023

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

GOES satellite imagery shows an area of low pressure gradually drifting northward in the Gulf of Alaska towards the Prince William Sound. Radar imagery shows precipitation has spread from just east of Seward northward towards East Anchorage and then eastward through the Sound to Valdez and over towards Cordova. The low has followed a more eastern track as some high-resolution guidance had been suggesting, with precipitation mostly keeping east of Anchorage.
Used a blend of high-res guidance for QPF/Snow forecast in the latest forecast package. Snowfall totals across Eagle River and Upper Anchorage Hillside east towards Whittier should be in the 1 to 3 inch range. Most of Anchorage will receive little to no accumulating snow today.

The heaviest snow will fall across the higher elevations of the eastern Chugach, including Thompson Pass. A blizzard remains in effect there where in excess of 12 inches of additional snowfall may occur today. Combined with wind gusts over 40mph, reduced visibility due to blowing snow is likely.

Low-amplitude ridging across southwest Alaska and the low in the Gulf of Alaska continues to result in a strong pressure gradient that lends itself to rather strong winds out of the AK Peninsula and also out of the Gaps along the coastal mountains. Seward, Whittier, and Valdez will maintain rather strong wind through the day. Strong wind will continue for Kodiak Island, though not quite as strong as yesterday. Latest satellite imagery shows that resuspended ash from Katmai has subsided through the night. Winds across this area will continue to relax through the day.

On Thursday, the low across the northern Gulf and PWS will gradually fill in (/weaken) with precipitation along the coast diminishing through the day. Meanwhile, a vigorous negatively-tilted trough will rotate through the AK Peninsula and towards the Kenai Peninsula.
Stout pressure will ensue, especially near the spine of the Kenai Mountains. A better defined surface low may develop right along the coast along the effective triple point, and/or may developing on the Cook Inlet Side of the Mountains. This will have an impact on placement of some precipitation, but especially wind profile.
That aside, precipitation should swiftly move up the Kenai Peninsula into both the PWS and Anchorage and Mat-Su Valley by Thursday afternoon. GFS, ECMWF, and their ensemble systems are all in quite good agreement with approximately 1 to 3 inches falling across Anchorage, with higher amounts near the coast and in the higher elevations. Interestingly, the 06z and 12z HRRR runs suggests the band will move so quick that up to a tenth of liquid (~inch of snow) may fall in Anchorage and the adjacent lower elevation areas with this band. Girdwood, Chugach, and coastal areas are still favored to receive a bit more snowfall regardless of solution. Cold temp profiles resulting in dry, low-density snow and gusty south winds up the Cook Inlet may result in some brief low visibilities as the band moves through and shortly thereafter.

Some precipitation may linger Friday coinciding with additional upper-level shortwave energy working with any leftover moisture.
Additional accumulation should be on the light side. Reinforcing cold air will filter in behind the troughs, leading to below average temperatures Friday and through the weekend for much of southcentral Alaska.

-Brown

.SHORT TERM FORECAST SOUTHWEST ALASKA AND BERING SEA/ALEUTIANS (Days 1 through 3/Tonight through Friday)...

Key Messages:

-Another round of elevated sustained winds and wind gusts expected through this afternoon along the Alaska Peninsula, with sustained winds up to 40mph and gusts up to 55mph possible, decreasing by this evening.

-Light freezing spray possible through tomorrow night along western Alaska, including Bristol Bay & the Eastern Aleutians.

-A diving Kamchatka low will bring increased rain & snow showers across the Bering Sea, Aleutians and Southwest Alaska through the end of the week.

- Up to 2" of snowfall possible for the Kuskokwim Delta, Lower Kuskokwim Valley, and Bristol Bay through Thursday. Intermittent periods of blowing snow could result in low visibilities.

Discussion:

No major changes to the forecast at this time as much of the AOR currently remains under mostly zonal flow aloft this morning with a developing low pressure system off the Kamchatka coast. This Kamchatka low will gradually shift SE towards St. Lawrence Island through this afternoon and eventually into Norton Sound by Thursday. This low and associated embedded shortwaves will send a shot of reinforcing cold air and lead to snow/snow showers for the eastern Bering and western coastlines of the mainland AK and the AKPen through the end of the work week, with forecast snowfall totals up to 2" possible. In addition, with increased winds on the backside of the low and increased snow ratios, expecting intermittent periods of blowing snow resulting in low visibilities for coastal areas along W AK through Thursday.
Temperatures will steadily trend downward over the next few days as the Arctic airmass settles in over interior AK.

.LONG TERM FORECAST (Days 4 through 7)
Saturday through Tuesday

In the West, high pressure extends into the Russian Far East, bringing gale force winds to the Western and Central Aleutians.
The main axis of the longwave trough over the Eastern Bering and Western Alaska wobbles and briefly reorients as a number of significant shortwaves rotate through the region. A closed center in the middle of the trough weakens as it drifts slowly around the Southwestern Mainland through Tuesday. Forecast confidence is mixed as deterministic models work initially, but ensembles work through the end of the forecast period. Colder air with the trough helps keep most precipitation as snow showers over the Aleutians, Bering and the Mainland Alaska. Locally heavy rains invade the Southern portions of the Alaska Peninsula, Kodiak Island and Southcentral, as Pacific lows are deflected into the Gulf. Gale force gap winds, with local areas of storm force winds spread from the Eastern Aleutians, over the AKPEN and around Kodiak Island.

Additional moisture from a North Pacific low as it comes close along the Eastern Aleutians and Alaska Peninsula Monday and Tuesday. Locally heavier precipitation spreads eastward with the low's track, along with gale force winds. As the lows move into the Gulf, the Eastern portions of Southcentral could see heavier periods of precipitation, and locally gusty winds approaching gales for Tuesday.

Kutz

AVIATION

PANC...Mostly VFR conditions through today. Light snow flurries is possible through this afternoon, but no significant accumulation is expected. Cloud ceilings may drop to or below 5000' this evening and a chance for some fog development overnight.

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Chiachi Island (east side)
Click for Map
Wed -- 02:12 AM AKST     Moonrise
Wed -- 02:40 AM AKST     2.69 feet Low Tide
Wed -- 09:22 AM AKST     6.38 feet High Tide
Wed -- 09:50 AM AKST     Sunrise
Wed -- 02:50 PM AKST     Moonset
Wed -- 03:59 PM AKST     4.22 feet Low Tide
Wed -- 05:04 PM AKST     Sunset
Wed -- 09:13 PM AKST     5.29 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Chiachi Island (east side), Alaska, Tide feet

Kupreanof Harbor
Click for Map
Wed -- 02:13 AM AKST     Moonrise
Wed -- 02:38 AM AKST     2.69 feet Low Tide
Wed -- 09:19 AM AKST     6.38 feet High Tide
Wed -- 09:50 AM AKST     Sunrise
Wed -- 02:51 PM AKST     Moonset
Wed -- 03:57 PM AKST     4.22 feet Low Tide
Wed -- 05:06 PM AKST     Sunset
Wed -- 09:10 PM AKST     5.29 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Kupreanof Harbor, Paul Island, Alaska, Tide feet

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