Marine Forecasts

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7 Day Forecast for Marine Location Near Port Lions, AK

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Area Discussion for -

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FXAK68 PAFC 311257 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 457 AM AKDT Sun May 31 2020

ANALYSIS AND UPPER LEVELS.

The pattern remains amplified as a large upper ridge extends along the west coast of North America into the northeastern Alaskan Interior. A broad upper trough currently extends from eastern Siberia and across the Bering/Aleutians. A closed upper level low is currently weakening over the eastern Gulf of Alaska while gradually weakening. A developing low is currently near 49N 167W and is moving northeastward. Water vapor imagery shows the trough-axis associated with this low changing from a positive to a negative tilt which is more conducive to cyclogenesis. An occluded front associated with this low is currently moving northeastward across the eastern Aleutians into the AKPEN. This front will bring rain to the eastern Aleutians northeastward through the APKEN.

At the surface, radar imagery shows showers moving southwestward across the Kuskokwim Valley into the Kuskokwim Delta. Another area of showers is moving southwestward across the AKPEN. Middleton Island radar shows showers moving westward across the northern Gulf. Temperatures continue to remain above normal due to the aforementioned Rossby Wave pattern with upper level ridging extending over the Alaskan mainland.

MODEL DISCUSSION.

The pattern remains amplified across the region with upper level ridging along western North America into mainland Alaska while upper level troughing persists across eastern Siberia through the Bering/Aleutians. Teleconnections (oscillations that effect the long wave pattern) support a change in the orientation of the Rossby Waves (long wave pattern) over the next week. During the next week the Western Pacific Oscillation (WPO) will change from the positive to negative phase while the Eastern Pacific Oscillation will change from the negative to the positive phase. At the same time, Pacific North American Pattern (PNA) will change from the positive phase to the negative phase. The ECMWF, GFS and GEM ensembles reflect these phase changes of the WPO, EPO and PNA and are in good agreement with the 500 mb height forecast as they show upper troughing develop over the eastern portion of the Alaskan mainland while upper ridging develop over the Bering/Aleutians, extending into Southwest Alaska. The result of this pattern change will allow for a warming trend across the Bering/Aleutians into Southwest Alaska over the next week while a cooling trend is to be expected across the eastern portions of the Alaskan mainland (Copper River Basin). This pattern will also allow for low pressure to more likely develop in the eastern Gulf as this location will be under an upper trough.

On the synoptic scale, guidance is in good agreement with respect to the placement and intensity of the aformentioned developing low that is moving northeastward over the next 1-2 days and then in fair agreement on day 3. The ECMWF appears to have a fast bias as the low center is much farther to the northeast on day 3 than the rest of guidance. Due to this forecast confidence remains high through Monday evening and then fair on Tuesday.

On the mesoscale, high resolution models were favored to better resolve local effects such as the Turnagain Arm wind.

AVIATION. PANC . Conditions will remain VFR through the TAF period. There is a chance of southeasterly gusts between 15-20kts through 16z today. As pressure gradients increase this afternoon in Turnagain Arm with the potential for up-inlet flow, there is the chance for southeasterly Turnagain winds after 00z. As the up-inlet flow weakens with down-inlet flow developing, these Turnagain winds are expected to ease after 14z.

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

An upper low which has been over the Gulf of Alaska over the last several days moves slowly north and weakens tonight. A secondary long wave trough moves north into the Gulf on Monday with a new upper low center developing. As a result, broad easterly flow continues across Southcentral through Monday. Embedded Easterly Waves in the upper flow track west bringing periods of showers or rain through tonight. Even though the thermal trough weakens and slips north, there still may be enough instability over the western Copper River Basin/Talkeetna Mountains to kick off a few thunderstorms this afternoon and evening. A weather front, associated with the north moving upper long wave, heads north toward Kodiak and the Gulf on Monday. This system will bring rain to Kodiak Island and perhaps the eastern Kenai Peninsula. Showers are expected elsewhere across Southcentral.

A weak coastal ridge and lower pressure inland increase pressure gradients along Turnagain Arm this evening. So expected gusty easterly winds to develop and likely clip south and west Anchorage before diminishing overnight tonight. Winds will likely develop again across Turnagain Arm and bend into town Monday afternoon as the coastal ridge strengthens some. Gusty southerly winds can also be expected along the Copper River.

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

Rainfall continues this morning across the Alaska Peninsula and the Kuskokwim Valley and Delta as seen on radar. Rainfall will continue throughout the day, with gusty winds possible, as upper level shortwaves continue to influence the area. Weak instability will be present this afternoon and tomorrow afternoon for the northern parts of the Kuskokwim Delta and Valley which will provide another chance for thunderstorm development in these areas. Temperatures look to be cooler today than they have been and will continue to cool into Monday.

SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2).

A front associated with a low pressure system south of Dutch Harbor is bringing gusty winds and rain to the eastern and central Aleutians as confirmed by METAR observations. These winds will continue to strengthen throughout the day, with the anticipation being that gale force will be reached later this morning. These winds will weaken to small craft before Monday morning, as the low remains nearly stationary south of Dutch Harbor. After this, the low will propagate eastward towards the Alaska Peninsula bringing continued rainfall to the eastern Aleutians and the AKPEN.

MARINE (Days 3 through 5). Gulf Of Alaska: A weak surface low situated in the northern Gulf on Tuesday will dissipate by Wednesday as it lifts north and west. Easterly small craft advisory winds associated with this system will also diminish by Wednesday. Areas of rain will continue across the northern half of the Gulf through Wednesday, reinforced by a secondary surface trough moving through the Gulf. Weak ridging then develops over the Gulf for Thursday in the wake of the trough.

Bering: A surface low south of the AKPEN Tuesday will bring northerly winds to much of the Bering into Wednesday. As this system tracks east, ridging will build in behind it, helping to further diminish wind speeds and cloud cover over the central and eastern Bering. A second system moving from west of Attu to the northern Bering on Thursday will bring increasing clouds, precipitation, and southerly winds to the western Bering.

LONG TERM FORECAST (Days 3 through 7). On Wednesday, the long wave pattern continues to show an extensive trough across much of the state. Embedded within the long-wave trough are two well defined upper level lows. The first is a vertically stacked low south of the AKPEN that will slowly work its way southeast and out of the Gulf by Friday. The second upper level low will transit from the Russian coast to Norton Sound by the end of the week. Between the two, a ridge will extend from Southwest Alaska to the Arctic ocean. As the first low moves east, the southerly flow aloft will return to a more northeasterly flow, allowing weak shortwaves to periodically move across Southcentral. This will reestablish the pattern of scattered afternoon and evening shower activity. The second upper level low will help spin up a frontal system that will cross the northern Bering through Friday before weakening as it runs into the ridge. A flat ridge will also remain in place across the Aleutian Chain, limiting clouds and precipitation and keeping temperatures on the milder side. Temperatures across the southern Mainland will also trend warmer through the extended forecast, but remain cooler than what we have seen the past couple of days.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . Gale Warning 155 165 170. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . ED SOUTHCENTRAL ALASKA . BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . CK MARINE/LONG TERM . CJ/TM

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
KDAA2 - 9457292- Kodiak Island, AK	21 mi	61 min	ENE 5.1 G 8.9	48°F	46°F		1004.1 hPa
46077 - Shelikof Strait, AK	76 mi	35 min	ENE 7.8 G 9.7	48°F	49°F	1 ft	1002.4 hPa (-1.6)	46°F
AMAA2 - East Amatuli Light, AK	77 mi	55 min	ESE 8.9 G 9.9	48°F			1005.5 hPa	48°F

Wind History for Kodiak Island, AK

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NE6

NE4 G7

NE5

E5 G9

NE6

NE5 G8

NE6 G10

NE4 G9

NE6 G9

NE7 G10

NE3 G6

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NE7 G11

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NE5 G9

NE1

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NE4

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E4 G7

1 day ago

NE5

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NE4 G7

SW6 G9

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N3

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NE5 G8

NE2

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N10 G20

NE11 G20

NE17 G23

N8 G16

N10 G17

NE12 G16

NE10 G14

NE8 G12

NW1

E4

E2

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SW4

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S2 G6

NE1

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SW4

SE2

SW5

SW4

NE7 G12

NE4

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Kodiak, Kodiak Airport, AK	20 mi	32 min	E 9	10.00 mi	Overcast	50°F	45°F	83%	1004 hPa

Link to 5 minute data for PADQ

Wind History from ADQ (wind in knots)

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NE6

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S3

NE6

SE4

Calm

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1 day ago

NE6

NE5

NE6

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NE6

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Calm

Calm

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NW14 G21

NW17 G28

N16 G24

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N7

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SE5

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Calm

W3

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W3

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6

Calm

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W8

NE10

NE5

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Tide / Current Tables for Fox Bay, Whale Island, Alaska

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Tide / Current Tables for Kizhuyak Point, 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

Other links: Northern Pacific     Contential US     Full GOES-East

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Ground Weather Radar Station Kenai, AK

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