Marine Forecasts

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7 Day Forecast for Marine Location Near Seldovia, AK

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Area Discussion for -

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FXAK68 PAFC 071446 CCA AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 500 AM AKST Sun Mar 7 2021

ANALYSIS AND UPPER LEVELS.

In the upper levels, a negatively titled trough with a broad low near the Kamchatka Peninsula and its impressive baroclinic front extends from the Chukchi Sea to the western Pacific. Ahead of this front, a low amplitude ridge of high pressure extends its axis over parts of southwest Alaska, Bristol Bay, and south of the central Aleutian Chain. Weak troughing sits over the Gulf, with a weak disturbance south of Kodiak Island that is slowly phasing with another stationary, potent low over the eastern Gulf. Latest ASCAT pass (scatterometer wind) is capturing small craft to gale force winds south of AKPEN to the western and central Gulf associated with cold air advection of these two distinct synoptic features. These winds are expected to slowly diminish today. At the surface, a weakening meso-low is moving south of Middleton Island and was responsible for light snow yesterday along coastal areas near Cordova and the surrounding higher elevations as well. Radar is picking up scattered light snow showers over the Y-K Delta associated with a weak low near St. Lawrence Island and its front that pushed into Coastal Southwest AK since late yesterday. The nighttime microphysics shows low stratus/fog completely blanketed over the southwest, AKPEN, and the eastern Aleutians. Additionally, low level ash emissions from the Veniaminof Volcano located north of Perryville was visible on satellite imagery overnight. With prevailing northwesterly winds aloft, the small ash plume was visible on satellite drifting southeast over the coastal waters west of Chirikof Island. The volcano has been fairly active over the past couple of days, but has quieted down this morning.

MODEL DISCUSSION.

Overall, model guidance are in consolidated agreement with the synoptic features for the short term and on track with an active weather pattern taking shape over the Bering/Aleutians as well as the Southern Mainland this weekend into early next week. The minor discrepancy with the latest model solutions has to do with the position, timing, and trajectory of a low expected to form along a frontal boundary near the western Gulf and Kodiak Island on Tuesday. Forecaster confidence remains moderate, with subsequent model runs hopefully ironing out some of these small scale discrepancies and the resultant weather that will have over the Southcentral coast.

AVIATION. PANC . VFR with light winds today, tonight expect fog and stratus to form and impact the airfield. IFR to LIFR conditions possible from midnight through Monday morning.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 to 3: Tonight through Tuesday) .

Outflow winds will continue through the day Sunday as a surface ridge building over the interior and a trough over the northern Gulf combine to increase the pressure gradient along the coast. A weakening shortwave moving across Southcentral today will also help enhance the gusty winds through favored gap locations throughout the day. These winds will begin to wind down, first over the Kenai and western Prince William Sound, this evening and across eastern Prince William Sound and the Copper River Delta by Early Monday morning as an upper level ridge builds in, ushering in warmer air aloft as well as a southwesterly flow.

Fog will be the biggest forecast challenge through Monday morning. Patchy fog may develop early this morning along Cook Inlet, but conditions will be more favorable for fog development overnight Sunday into early Monday morning as the ridge crests overhead with warmer air moving in aloft. Fog early Monday morning may expand to include not only areas around Cook Inlet, but locations in the Mat-Su Valleys and Copper River Basin. Fog may also develop along the immediate coast, especially near Cordova and Valdez.

By late Monday, the weather pattern will change and become more active as a front moves east toward Southcentral. A low is expected to form along the front Monday night somewhere north of Kodiak Island and track into the northern Gulf toward Prince William Sound for Tuesday. A deep southerly fetch of warm, moist air will accompany this system, with the warmer air likely allowing for snow to change to a rain/snow mix or even all rain along the immediate coast. For interior locations, enough cold air is expected to remain in place for the precipitation to fall as all snow. With the flow aloft south to southwest, the highest precipitation totals are expected along the coastal mountains as well as the northern half of the Susitna Valley, including Talkeetna and Broad Pass, as well as Hatcher Pass. A cross- barrier flow may keep precipitation at bay initially for the western Kenai Peninsula and Anchorage Bowl. However, accumulating snow is possible by Tuesday afternoon as the low continues its northeasterly track toward Prince William Sound and the cross- barrier flow weakens.

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 2: Today through Monday night) .

The P-type and the potential for blowing snow are today's forecast challenges for the next frontal system approaching Mainland Southwest specifically along the Kuskokwim Bay and Kuskokwim Delta this evening into Monday morning. Though MOS guidance favors snow and blowing snow conditions over Kuskokwim Delta, warm southwest winds advecting inland tells a different story favoring rain than dry snow ahead of the front. At mid to upper-levels, strong winds could also reduce or eliminate the potential for blowing snow.

The front's forward motion hasn't been promising and remained a struggle for this forecast package. Its delayed motion led to updating winds, sky cover, QPF, and POP grids to reflect the latest situation. Cold air advection trailing behind the cold front will begin to fill Y-K Delta Coast as soon the front passes Nunivak Island Monday morning, causing temperatures to decline into Monday night. Over Bristol Bay, rain/snow mix is expected there, and mainly rain for AKPEN as warmer temperatures linger there through the forecast period. Overall, the expected front will be the main weather producer for the region. Stay tuned!

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 2: Today through Monday night) .

The infamous front off an Arctic low will move across the Bering Sea and Aleutians through this evening. A push of warm air out ahead of the front will increase temperatures across the Aleutian Chain enough for precipitation to be rain or a rain/snow mix. Moderate to heavy precipitation is expected along the eastern Aleutians and southern AKPEN as the front passes. Weak low pressure remains behind the front as well as persistent westerly flow. Winds should also diminish behind the front, becoming mostly small craft along the Aleutian Coasts.

MARINE (Days 3 through 5: Tuesday through Thursday).

Bering: An Eastern Bering front moves into Western Alaska Tue night. Forecast tracks vary somewhat, but confidence is good. Areas of small craft winds and waves dissipates Wed. Seas to 12 feet, subsiding. Several troughs cross the Bering through Thu, with winds less than small craft level. A new low and front moves into the Western Bering for Wed night and Thu. Widespread increasing gale force winds move across the Western Bering. Seas building to 16 feet Thu.

Gulf of Alaska: A low and front move across the Gulf for Thu. Forecast tracks vary somewhat, but confidence is good. Widespread southerly small craft winds and waves move across the Gulf for late Tue, becoming widespread westerly small craft winds with an area of gale force winds from the Barren Islands into the Northern Gulf for Wed. Winds diminish Thu over the Northern Gulf. Seas to 12 feet, subsiding Wed.

LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday).

An analysis of long term guidance leads us to have moderate confidence that we can expect changing weather conditions for the Bering and Gulf of Alaska, while mainland AK stays quiet with cold overnight temperatures through the week.

Wednesday, on the synoptic scale, longwave troughing will generally encompass our forecast area. A high amplitude ridge is exiting to the east and over the Yukon, while a low amplitude ridge is moving into the far Western Bering. On the surface, models are indicating a compact low skirting along the north side of the Aleutians in the Bristol Bay area. Low pressure is also lingering in the Prince William Sound area. The rest of the forecast area looks to be quiet and under high pressure. This means cooler overnight lows continue for mainland AK.

Going forward through late next week, in the upper levels models are showing the low amplitude ridge in the Western Bering moving east and building over Western AK. Troughing re-emerges over the Western Bering and over mainland AK south into the Gulf of Alaska. On the surface high pressure holds on in Mainland AK and Eastern Bering, though models are teasing a surface low moving into the West Coast. Low pressure continues in the Gulf and Western Bering. Models are having discrepancies in handling specific features, at most hinting at what might happen. So for now, we are sticking to identifying the general pattern, which the long range guidance does have at least moderate agreement on.


AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . Gale Warning 155 160 165 170 172-176 178-185 411-414. Heavy Freezing Spray Warning 185 411.. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . MF/TM SOUTHCENTRAL ALASKA . TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . CB MARINE/LONG TERM . MK/BB

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
OVIA2 - 9455500 - Seldovia, AK	1 mi	50 min			38°F		1022.7 hPa (+0.3)
46108 - Central Cook Inlet - 175	12 mi	50 min		32°F	38°F	1 ft
FILA2 - Flat Island Light, AK	17 mi	20 min	NNE 13 G 15	32°F			1022.7 hPa	17°F
HMRA2 - Kachemak Bay Reserve, AK	19 mi	80 min	NE 15				1021 hPa
HMSA2	19 mi	18 min	NW 2.9 G 7	34°F				19°F
APXA2	23 mi	125 min	NE 2.9	28°F			1024 hPa	13°F
AMAA2 - East Amatuli Light, AK	39 mi	20 min	NW 17 G 27	34°F			1021.5 hPa	18°F

Wind History for Nikiski, AK

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Seldovia, Seldovia Airport, AK	1 mi	57 min	N 0	10.00 mi		32°F	19°F	59%	1023 hPa
Homer, Homer Airport, AK	18 mi	57 min	WSW 10	10.00 mi	Fair	32°F	17°F	54%	1022.8 hPa

Link to 5 minute data for PASO

Wind History from ASO (wind in knots)

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Tide / Current Tables for Seldovia, Alaska

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Tide / Current Tables for Port Graham, Alaska

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Weather Map

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