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PKZ730 West Of Barren Islands Including Kamishak Bay- 305 Am Akst Fri Dec 8 2023
.small craft advisory through Saturday...
Today..W wind 25 kt becoming sw 15 kt in the afternoon. Seas 6 ft. Freezing spray.
Tonight..Variable wind 10 kt becoming N 25 kt after midnight. Seas 4 ft.
Sat..N wind 30 kt. Seas 8 ft. Freezing spray.
Sat night..E wind 20 kt. Seas 5 ft.
Sun..NE wind 35 kt. Seas 10 ft.
Mon..N wind 25 kt. Seas 7 ft.
Tue..NW wind 25 kt. Seas 6 ft.

PKZ700
No data

FXAK68 PAFC 081416 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 516 AM AKST Fri Dec 8 2023

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

A somewhat quieter day is in store for much of southcentral Alaska in wake of the trough and associated cold front that brought several inches of snowfall to the area on Thursday.

The front has now pushed off to the eastern Gulf of Alaska. Strong cold air advection behind the front, characterized by 850mb temps near -15C, will yield rather steep low-level lapse rates over the open water. Satellite imagery along with the Middleton Island Radar (PAIH) shows rather robust convective showers over the Gulf and portions of Prince William Sound. These showers are expected to continue to move across the water and into eastern Prince William Sound and the Copper River Delta amid southeast flow throughout the day on Friday and into Friday night. The primary forecast challenge with this regime is the potential for additional accumulating snowfall in the Cordova area. Given the scattered nature of the showers, it's quite possible additional accumulation will be minimal... though a quick inch or two cannot be ruled out. Most activity will remain south of Tatitlek, but wouldn't rule out snow showers for Valdez as well.

Light snow may linger a bit this morning from Anchorage north through the Mat-Su Valley, as well as the parts of the northern Copper River. Additional snow accumulation today for most of southcentral will be limited to an inch or two.

By late this evening, models indicate another shortwave trough rotating through the AK Peninsula and Kodiak Island. Precipitation will once again focus on the associated surface trough/low that develops and move up the Gulf of Alaska off the Kenai Peninsula.
Despite being in short forecast range, there remains some significant model spread (and therefore forecast uncertainty)
regarding the placement of this trough and snow, as well as the timing. The 06z NAM brings another round of 2 to 4 inches of snowfall on Saturday for portions of the Kenai Peninsula and up into Anchorage and the Mat-Su Valley. Meanwhile, the ECMWF and GFS operational runs are about 6-12 hours slower and a bit farther east.
This could still provide a couple inches for Anchorage and perhaps the Mat-Su Valley, but generally lesser amounts. The ensemble systems are also about 50/50 split on track and QPF. Ultimately this is a forecast that'll continue to be dialed in today as models (hopefully) get into agreement.

Another much stronger system - with potential for widespread and potentially moderate to heavy precipitation - will begin to take shape on Sunday as a flat ridge begins to build into the Gulf while a large, deep North Pacific low organizes south of the Alaska Peninsula and begins to interact with the Arctic air in place over portions of the Mainland. Model agreement by this point is rather poor regarding details at this juncture, but expect an active pattern with potential for additional rounds of widespread precipitation across much of Southcentral starting as early as Sunday/Monday. Stay tuned as we monitor for the potential for more impactful winter weather by the start of next week.

As far as temperatures are concerned, much of southcentral Alaska will run about 5 to 10 degrees below climatological average this weekend before moderating to near- or above-average early next week.

-Brown/AS

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Sunday)...

An upper trough persists over the Kuskokwim Delta through Saturday with one or more shortwaves to rotate through the trough and just offshore of the Kuskokwim coast. High pressure remains over the western Bering, while an eastward moving shortwave trough tracks south of the Aleutians before eventually wrapping northward into the Greater Bristol Bay area on Sunday. The Kuskokwim Delta trough will sag slightly southward with the passage of each shortwave today and tomorrow. A pattern change then begins to develop by Sunday as the trough phases with the wave lifting into Bristol Bay, forming a much more amplified trough over the AKPEN and Western Alaska Range over the latter half of Sunday.

For today, previously elevated winds over the Kuskokwim Delta should begin to taper of through this afternoon as the trough slowly sags southward. A winter weather advisory for Mekoryuk and the Kuskokwim Delta coast will be allowed to expire this morning.
Calmer conditions continue for the rest of Southwest Alaska.
Scattered light snow will remain possible today and tomorrow while the presence of the upper trough lingers over Southwest Alaska.
There is some uncertainty in regard to potential heavier snow amounts over the Greater Bristol Bay region. The area could see a one-two punch, with a long- duration period of light to moderate snow late today into Saturday, and then a second round of light to moderate snow on Sunday. The NAM seems to be the most aggressive model with Iliamna accumulating 4 to 6 inches of the white fluffy stuff through the weekend. Finally, the Kuskokwim Delta should experience a notable temperature drop over the next 36 hours.
Current temperatures in the teens steadily decrease to near zero by Sunday morning as northerly flow opens up over the Kuskokwim Delta.

Elsewhere, northerly flow will dominate the Bering Sea. The only significant change will occur over the Western and Central Aleutians. A front and corresponding southeasterly winds today will see above freezing temperatures drop back down to freezing or below freezing through tomorrow, as the front gets pushed southward through tonight. Models show a subfreezing air mass spill well south of the Aleutians through Sunday morning, as the previously mentioned Aleutian shortwave tracks out of the way of the incoming air mass to the east.



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

The longwave trough extending over Western Alaska undergoes some moderate broadening as some energetic shortwaves rotate through the pattern. The main axis drifts Eastward, and the mid-trough low center dips into into the Gulf of Alaska by the end of the period. Ridging on both sides maintains their amplitude. Ensemble forecast keeps a good forecast basis for all features, with the exception of the shortwave traffic along the Western Alaska coast.
Gusty Northerly winds over the Eastern Bering increase to gale force for late Tuesday through Thursday. An approaching North Pacific low and front expand the areas of gales across the Central and Eastern Aleutians Wednesday and Thursday. A moderate front approaches the Western Aleutians and Bering, bringing Southerly gales from midweek on. Locally moderate snow showers over the Bering give way to mixed rain and snow or rain along the Aleutians and Alaska Peninsula by the end of the forecast period.

As the trough slides to the East, increasing moisture pushes inland across Southcentral to the Alaska Range ahead of the North Pacific low moving into the Gulf through Thursday. This low brings an extended fetch of moisture which will add to expected multi- day precipitation events. Coastal zones into the Prince William Sound area will see locally heavier mixed rain and snow changing to rain Tuesday. Interior areas should remain snow, with a transition zone around the Anchorage area. Gusty winds around Kodiak Island will be close to gale force on Monday, diminishing Tuesday.

Kutz

AVIATION

PANC...Light snow may linger through the morning. Lower visibilities and MVFR to IFR cloud ceilings may accompany periods of snowfall, gradually raising to marginal in the early afternoon and to VFR by late afternoon.

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Iliamna Bay
Click for Map
Fri -- 04:31 AM AKST     Moonrise
Fri -- 04:53 AM AKST     4.49 feet Low Tide
Fri -- 09:58 AM AKST     Sunrise
Fri -- 11:05 AM AKST     12.99 feet High Tide
Fri -- 02:28 PM AKST     Moonset
Fri -- 04:13 PM AKST     Sunset
Fri -- 05:51 PM AKST     2.45 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Iliamna Bay, Alaska, Tide feet

Oil Bay
Click for Map
Fri -- 12:09 AM AKST     10.14 feet High Tide
Fri -- 04:30 AM AKST     Moonrise
Fri -- 05:53 AM AKST     4.54 feet Low Tide
Fri -- 09:57 AM AKST     Sunrise
Fri -- 12:08 PM AKST     12.51 feet High Tide
Fri -- 02:27 PM AKST     Moonset
Fri -- 04:12 PM AKST     Sunset
Fri -- 06:51 PM AKST     2.47 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Oil Bay, Kamishak Bay, Alaska, Tide feet

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