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 121237 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 437 AM AKDT Wed Aug 12 2020

ANALYSIS AND UPPER LEVELS.

The upper low from yesterday remains just north of the Alaska Range early this morning, and it will continue to influence local conditions by generating thunderstorms and showers over much of Southcentral Alaska today and tonight. A strong shortwave extends southward from the aforementioned upper low through Southcentral, then runs westward through Kusko Bay then turns northward past Yukon Delta. Increased moisture and rainfall have shifted further east of Wrangell Mountains and further north of Alaska Range. West of this low, an upper level high will maintain low level clouds/stratus over much of Kusko Bay and Bristol Bay early this morning, then gradually weakening with daytime heating. A vertically stacked low near the Aleutian Islands is centered northwest of Atka, and weather reports indicated an extensive area of patchy fog and low clouds over Bering Sea and Aleutians. South of the Aleutians, an elongated area of tropical moisture or baroclinic zone runs through eastern Aleutians and south Alaska Peninsula (AKPEN), and this will bring increased moisture and clouds over western Gulf throughout today.

MODEL DISCUSSION.

Computer model resolutions are in accord for most of the large scale features except on the motion and location of the emerging low south of AKPEN in the coming days. Although the synoptic low over the Aleutians will strengthen the next circulation overlaid by the baroclinic zone, solutions begin to split starting Friday morning as this emerging low enters western Gulf through the weekend. Overall, solutions are doing a good job handling the latest weather pattern.

AVIATION.

PANC . The main forecast challenge would be forecasting thunderstorms today and tonight, especially whether thunderstorms will occur nearby or right over Anchorage Bowl. Shower bands continue to move from south to north, with the anticipation of increased showers later in the day. Otherwise, light winds and VFR conditions will prevail.

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

A broad upper trough over Southcentral will continue showery weather across the region. Cold air aloft and a strengthening thermal trough will increase afternoon and evening thunderstorm potential over inland areas from the Kenai Peninsula to MAT-SU Valleys (including Anchorage Bowl) and Copper River Basin through Thursday. Southcentral overall will experience a slow warming and drying trend. Weak offshore flow with localized outflow winds tonight will diminish on Thursday and give way to afternoon seabreezes. Patchy fog will diminish in inland by the mid morning hours.

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

Expecting a pattern change to occur late on Wednesday as the upper level low that has provided lift for afternoon and evening showers moves off to the southeast. There is a slight chance for an isolated thunderstorm or two over the Western Alaska Range today due to the shortwave and some mild instability building over the region throughout the day. Otherwise, the weather is looking hot and increasingly dry through Fri as a ridge builds over the central Bering Sea. This ridge location puts Southwest in the zone of subsidence, with offshore surface flow from the interior also helping to dry things out.

The southern AKPEN should be the only area to receive rainfall starting early Thu morning. Models indicate a slight perturbation in an area of baroclinicity embedded within the jet to the south of the Aleutian Chain. This perturbation is expected to form into a surface low that will move off of the southern AKPEN coast Thu morning. As the system moves north, it's expected to absorb the remnants of an upper level low over the Central Aleutian Chain. This will bring persistent rain over the southern AKPEN through Fri as the two systems interact.

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

An occluded low over the Central Aleutians Wed is expected to continue to weaken as it moves slowly east through Thu. The weather impacts from this storm will continue to be rain and light winds. To the north, surface high pressure currently centered over St. Lawrence island is expected to expand and occupy the northern and central Bering by Fri. This should keep the winds on the light side and also create some fog and low stratus. The pattern will then again to change over the Western Aleutians Thu night as the next frontal system comes in. Models are in good agreement in regards to small craft advisory winds and rain from Shemya to Amchitka by Friday. Some solutions indicate Gales over the Western Aleutians by Friday night but there is still uncertainty in this forecast.

MARINE (Days 3 through 5: Friday through Sunday).

Aleutians/Bering: Light winds with high pressure moves into the Eastern Bering for Sun. A North Pacific low and its front moves into the Western Bering through Sun. While the track and development of the low vary through the forecast, confidence is good for the front to spread showers and Southeasterly small craft winds and waves with local gales developing over the Western Aleutians Eastward for Fri afternoon. As the low tracks into the Western Bering, winds and waves will wrap the low and spread into the Eastern Bering by Sun. Southerly winds move with the front, Easterly then Northerly follow behind the low.

Gulf of AK: High pressure over the Gulf dissipates for Sat. A North Pacific low and its front moves along the Southern Gulf through Sun. Confidence is good for showers and Easterly small craft winds and waves across the Southern Gulf to spread Northward mostly in the Eastern Gulf through Sun. High pressure enters the Western Gulf Sun.

LONG TERM FORECAST (Days 4 through 7: Sat through Tue). Model agreement has began to improve a bit with the track a developing North Pacific low moving into the Western Aleutians this weekend. While there are small differences with regards to timing, there is general consensus that this system will bring gale force winds and rain to the Western-Central Aleutians for Saturday. This agreement then quickly breaks down Sunday into early next week, especially when looking at the last 2 runs from the GFS. The GFS has begun to trend with a much deeper low tracking into the Bering Strait, while the EC/CMC and other ensembles continue to track this system much weaker through the AKPen. After coordinating with WPC, the long term forecast will treat these GFS solutions will be treated as an outlier for now, but this will need to be continue to be monitored. If other models begin to trend this direction, significant changes to the forecast will be needed for the Southwest Mainland early next week.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . NONE. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . CB SOUTHCENTRAL ALASKA . BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . CJ MARINE/LONG TERM . MK/DK

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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	46 min			53°F		1014.3 hPa
FILA2 - Flat Island Light, AK	17 mi	34 min	WSW 5.1 G 5.1	55°F			1014.8 hPa (+0.0)	52°F
HMSA2	19 mi	22 min	W 7 G 11	56°F			1011.9 hPa	51°F
AMAA2 - East Amatuli Light, AK	39 mi	34 min	WSW 8 G 8.9	55°F			1015.2 hPa	54°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	41 min	N 5	10.00 mi	Fair	60°F	54°F	80%	1014.7 hPa
Homer, Homer Airport, AK	18 mi	42 min	W 7	10.00 mi	Showers in Vicinity	61°F	53°F	77%	1014.6 hPa

Link to 5 minute data for PASO

Wind History from ASO (wind in knots)

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NE4

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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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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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