Marine Forecasts

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7 Day Forecast for Marine Location Near Seldovia city, AK

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Area Discussion for -

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FXAK68 PAFC 280109 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 509 PM AKDT Fri Mar 27 2020

ANALYSIS AND UPPER LEVELS. A strong blocking ridge is centered over the north central Pacific, with a trough over mainland Alaska. The jetstream extends northward up the west side of the ridge to the Aleutians, then turns eastward, with zonal flow from the eastern Bering Sea to the Gulf of Alaska. A gale force low over the northern Bering Sea is tracking eastward toward the west coast of Alaska. The original frontal system from this low has weakened considerably as it pushed inland across Southwest Alaska and into the western Gulf today. What remains is some areas of light snow, particularly along the west side of the Alaska and Aleutian Ranges, with some light snow on the Kenai Peninsula and rain down over the Gulf. Another round of snow is making its way onshore along the Kuskokwim Delta coast as the low center approaches. This is accompanied by strong and gusty winds due to cold air advection and instability, leading to areas of blowing snow and reduced visibilities.

Cold air advection extends south of the low center (over the northern Bering) eastward across the Alaska Peninsula into the Southwest Gulf. This is producing strong gap winds (up to storm force) along the Alaska Peninsula. Meanwhile, due to the combination of Arctic air in the Copper River Basin and tight pressure gradients from there down to the Gulf, gap winds are also affecting portions of the Matanuska Valley, the Valdez area, and the Copper River Delta.

MODEL DISCUSSION. Models are in better (but not perfect) agreement with the many short-waves transiting the eastern Bering Sea, southern Alaska, and Gulf of Alaska tonight through Saturday. Therefore, confidence in the snow accumulation forecast for both Southwest and Southcentral has increased.

AVIATION. PANC . A short-wave crossing the Alaska Range this evening will clip Anchorage, with light snow likely at the terminal this evening through the overnight hours. With weak forcing and low level westerly flow (favoring snow along the mountains), expect ceiling/vis to bottom out at MVFR. There is also a chance that most of the snow falls east of the terminal and VFR conditions prevail for much of this time. No matter what, offshore flow will develop during the day Saturday causing ceilings to lift. The passage of an upper short-wave tomorrow afternoon combined with cold air advection will lead to increasing northerlies, likely becoming gusty after 00Z Saturday.

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2).

Elevated winds along the northern Gulf coast continue to gradually weaken as a surface low drifts toward the southeastern Gulf. A weak frontal boundary associated with an upper level trough has moved in over Southcentral, producing mostly virga this afternoon. Snow becomes increasingly likely this evening, with accumulations on the order of trace to 2 inches possible overnight into Saturday morning. The upper level low then deepens and moves southward over the Gulf, leading to another outflow wind event Saturday night. As the low pulls away, cold Arctic air will be drawn down from the north, lowering temperatures and allowing northerly winds to pick up Saturday night. Areas including Seward, Palmer, Valdez, and the Copper River Basin will once again see elevated gusty winds Saturday into Sunday. Skies are expected to clear for the rest of the weekend and into early next week as colder northerly flow persists.

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight through Monday) .

A low moving into Southwest Alaska from the northern Bering is causing snow to redevelop across the Kuskokwim Delta this afternoon. The low will track southeastward across the Kuskokwim Delta and Bristol Bay tonight into Saturday morning. 1 to 3 inches of snow are possible overnight tonight across many areas of Southwest Alaska. Behind the low, strong north to northwesterly winds following the low will cause snow to blow around, which may temporarily reduce visibilities to one half mile at times. The Winter Weather Advisory for the Kuskokwim Delta therefore remains in effect until 7am Saturday morning. During the day Saturday, the snow will largely end from northwest to southeast, though upslope snow showers over the Kuskokwim Mountains and Alaska Range will persist throughout the day. The primary effect of the weather on Saturday will be colder air building southward across Southwest Alaska and gradually clearing skies. Due to the strong late March sunshine, it will likely take until Saturday night for the really cold temperatures to be felt.

Polar high pressure builds into Southwest Alaska on Sunday and Monday. This will lead to temperatures falling to between zero and 10 above for low temperatures in most locations, while highs during the day rise to near 30, once again due to the strong late March sunshine, which should be abundant both days under sunny skies.

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Tonight through Monday) .

A low over the northern Bering will move into Southwest Alaska tonight, as high pressure builds over the western Bering. A front moves into the central and western Bering Saturday afternoon, which will dissipate on Sunday. A second stronger front moves east into the western Aleutians and western Bering late Saturday night. It will weaken as it moves to the Pribilofs and eastern Aleutians on Monday. Most models suggest a weak low develops along that front near Cold Bay Monday afternoon, but there are some discrepancies on that.

The strong winds and cold temperatures behind the low tonight and Saturday will produce areas of heavy freezing spray, which will spread north to south across the eastern Bering through the Alaska Peninsula. This could become impactful to shipping in these areas, particularly south of the Alaska Peninsula, where cold air and strong winds together have been absent for quite a while.

MARINE (Days 3 through 5/Sunday through Tuesday).

Bering Sea/Aleutians . A storm system will track across the western to central Bering on Sunday. There is uncertainty in the exact track of the low center, but high confidence in widespread small craft winds with gales likely near the low center. The eastern Bering will likely see minimal impacts from this, as most model solutions track the low to the northern Bering, or even into Russia. Forecast confidence for Monday/Tuesday drops significantly, although it doesn't look like any major storm systems will affect the region.

Gulf of Alaska . There is a high confidence in gap winds along the Gulf coast on Sunday. These will diminish by Monday and the overall weather pattern looks quiet.

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

Guidance is consistent with the overall synoptic pattern on Sunday with an upper level trough over the Alaska mainland while upper level ridging slowly moves eastward across the central and eastern Bering. This will result in cold temperatures across the mainland. A high confidence exists with a warming trend in temperatures across the Alaska mainland in particular Southwest Alaska Sunday through Tuesday. However, there is low confidence with respect to the magnitude of the expected warm up as there are discrepancies between guidance with how fast this ridge is moving. The GFS appears to have the fastest bias as the GEM and ECMWF show the upper trough extending into the Ahklun Mountains while the GFS has the trough only extending to the eastern AKPEN. More significant differences between guidance arise on Wednesday with respect to the amplitude of the upper ridge over Southcentral Alaska. This means that there is a low confidence in the temperature forecast as the placement of this upper ridge affects the placement of the surface ridging and thus causing major discrepancies in the temperature forecast. One area of confidence for this period is the weather is expected to remain benign across Southcentral during this time as high pressure will be over the area. Significant discrepancies continue on Thursday and Friday and thus the forecast confidence remains very low for this period at this time.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . Winter Weather Advisory 155 MARINE . Gale 127 132 138 150 185 Heavy Freezing Spray 119 140 160 180 181 185 414 FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . SB SOUTHCENTRAL ALASKA . KO SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . JW MARINE/LONG TERM . SB/ED

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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	54 min			40°F		1004.5 hPa (-1.2)
FILA2 - Flat Island Light, AK	17 mi	24 min	W 16 G 18	37°F			1004.7 hPa	32°F
HMRA2 - Kachemak Bay Reserve, AK	19 mi	84 min	ESE 1	32°F			1004 hPa	24°F
HMSA2	19 mi	22 min	SE 2.9 G 4.1	32°F			1001.9 hPa	25°F
AMAA2 - East Amatuli Light, AK	39 mi	24 min	WNW 5.1 G 8.9	37°F			1004.8 hPa	29°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	61 min	N 0	10.00 mi	Partly Cloudy	31°F	26°F	82%	1004.9 hPa
Homer, Homer Airport, AK	18 mi	61 min	N 0	10.00 mi	Fair	27°F	19°F	75%	1005.1 hPa

Link to 5 minute data for PAHO

Wind History from AHO (wind in knots)

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Tide / Current Tables for Port Chatham, Cook Inlet, Alaska

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Tide / Current Tables for Homer, Kachemak Bay, Cook Inlet, Alaska

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Weather Map

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GEOS Local Image of Alaska    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

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Ground Weather Radar Station Kenai, AK

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