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PKZ752 Castle Cape To Cape Tolstoi Out To 15 Nm- 315 Am Akst Tue Dec 5 2023
.gale warning today...
Today..NW wind 35 kt. Gusts to 50 kt out of bays and passes. Seas 6 ft. Freezing spray.
Tonight..NW wind 30 kt.gusts to 45 kt out of bays and passes. Seas 6 ft.
Wed..W wind 25 kt. Seas 5 ft.
Wed night..W wind 25 kt. Seas 5 ft.
Thu..W wind 20 kt. Seas 3 ft.
Fri through Sat..W wind 15 kt. Seas 4 ft.

PKZ700
No data

FXAK68 PAFC 051415 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 515 AM AKST Tue Dec 5 2023

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

A gale force low in the Southern Gulf of Alaska will continue to slowly drudge northward today, tonight and Wednesday with the latest ECMWF, Canadian and NAM model consensus of a 983 mb low tracking slowly north to be located around 45 nm southeast of Middleton Island Wednesday morning. The GFS has a low of similar strength but tracking further to the west and slower than the other models. Model tracks become more divergent into Thursday with the ECMWF, Canadian and NAM consensus track moving the low into the Copper River Delta to the east of Cordova Wednesday evening while the GFS tracks the low northwest into the Eastern Kenai Peninsula and Western Prince William Sound and dissipating Thursday afternoon. Based upon current low track and model performance we preferred the faster, slightly weaker and further east track of the ECMWF, Canadian, and NAM as well as sever other high resolution models over the GFS which seems to be an outlier solution at this point.

The faster, weaker and further east track will manifest itself with a shorter initial precipitation period, with lesser snowfall totals especially on the western edge of the storm over Cook Inlet, the Western Kenai Peninsula, Anchorage and the MatSu valley with the first round of snow as the low moves north and makes landfall along the coast near the Copper River Delta, but may produce more snow on the back side of the low as it moves north into the Copper River Basin and cold west to northwest flow produces upslope flow along the Chugach Front Range over the Western Kenai Peninsula, the Anchorage Hillside and Eagle River as well as the Talkeetna Mountains and the MatSu valleys. Snowfall totals through Wednesday afternoon range from 1 to 6 inches depending on the track of the storm. Higher amounts will be possible in the southern Copper River Basin & Thompson Pass, where more moisture is wrung out over the coastal mountains. Blowing snow is expected to be an additional hazard for Thompson Pass as cold air continues to filter out through gaps, leading to continued sustained winds of 40 to 50 mph. Small changes in the track of this storm will produce large differences in the timing, and location of the heaviest snowfall.

By Wednesday, the low moves into the northeastern Gulf, drawing cold air across the Western Alaska Range. This cold air advection is likely to enhance gap winds in the western Gulf to storm force, with gusts in excess of 65 knots (75 mph). Precipitation will begin to diminish Wednesday evening in Prince William Sound and surrounding mountains, but upslope snow showers will likely linger along the Front Range of the Chugach and Talkeetna mountains including the Anchorage area and the MatSu Valleys into Thursday as a broad low with a strong upper-level component tracks into Western Alaska. Its cold front brings potential for another round of snow to Southcentral as it sweeps eastward out over the Gulf.

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

Key Messages:

-Elevated sustained winds and wind gusts expected across much of SW Alaska & the Bering through Wednesday afternoon, with gusts up to 65mph possible along the Alaska Peninsula.

-A developing Kamchatka low will bring increased precipitation chances to SW AK through the central Aleutians by tomorrow night.

Discussion:

No major changes to the forecast at this time as much of the AOR currently remains under mostly zonal flow with weak ridging aloft.
In tandem with a low pressure within the GoA, anticipating another day of elevated & gusty winds to traverse across the Alaska Peninsula, with sustained winds around 40mph and isolated gusts up to 60-65mph possible through gap-wind areas like King Cove, Sand Point and Chignik. Good news, these winds will slowly weaken through Wednesday afternoon as the pressure & temperature gradient relaxes with the Gulf low opening & sliding eastward towards Prince William Sound.

Out west over the Bering, expecting cooler temperatures and intermittent snow showers to persist through the forecast period under predominate W/NW-ly flow, aided by a developing and compact Kamchatka low. This Kamchatka low will gradually deepen and shift SE towards St. Lawrence Island through Wednesday and eventually over mainland AK by Thursday. This low will send another shot of reinforcing cold air and lead to heavier snow/snow showers for the Bering and western coastlines of the Mainland and AKPen to round out the short term forecast.

.LONG TERM FORECAST (Days 4 through 7)
Friday through Monday

The longwave trough over the eastern Bering and western Alaska, meanders and drifts southeastward into the Gulf of Alaska with a surface low heading toward the eastern Gulf of Alaska. There is low confidence for the weekend period with the location of the surface and where the heaviest precipitation will be, but expecting an active pattern ahead for eastern Alaska. High pressure ridging continues indicate amplification for the western Bering Sea that encourages cool, northerly flow across the Bering Sea. Snow showers can be expected under the northerly flow, especially for the central and east Bering. A closed low forms over Southern Mainland, and drifts to the East through the weekend.

A North Pacific low with more available moisture and winds approaching gale force will lift northward toward the Aleutians, but looks to drift east toward the Gulf before reaching the Islands. Bands of precipitation would still be reinforced and would like keep precipitation going, locally heavier at time along the Aleutians. Another surface low appears to develop and south of the Alaska Peninsula and tracks into the western Gulf. At this time, potentially heavy precipitation (10 percent exceedance of 2 inches in 24 hours) to the northern Gulf coast early next week is possible. There is still low confidence with the position of the low this far out in time, but is a feature worth tracking over the next few days.

rux

AVIATION

PANC...Mostly VFR conditions through this afternoon, although cloud ceilings at or below 5000' are expected to continue this morning. A wintry mix will continue this morning followed by a brief break in the afternoon. Later this evening, snow chances return and conditions will drop to MVFR or lower at times.

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Chiachi Island (east side)
Click for Map
Tue -- 12:56 AM AKST     Moonrise
Tue -- 01:47 AM AKST     2.17 feet Low Tide
Tue -- 08:36 AM AKST     6.04 feet High Tide
Tue -- 09:48 AM AKST     Sunrise
Tue -- 02:39 PM AKST     5.03 feet Low Tide
Tue -- 02:46 PM AKST     Moonset
Tue -- 05:05 PM AKST     Sunset
Tue -- 07:51 PM AKST     5.56 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Chiachi Island (east side), Alaska, Tide feet

Kupreanof Harbor
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Tue -- 12:57 AM AKST     Moonrise
Tue -- 01:45 AM AKST     2.17 feet Low Tide
Tue -- 08:33 AM AKST     6.04 feet High Tide
Tue -- 09:49 AM AKST     Sunrise
Tue -- 02:37 PM AKST     5.03 feet Low Tide
Tue -- 02:46 PM AKST     Moonset
Tue -- 05:06 PM AKST     Sunset
Tue -- 07:48 PM AKST     5.56 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Kupreanof Harbor, Paul Island, Alaska, Tide feet

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