Marine Forecasts

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7 Day Forecast for Marine Location Near Point Possession, AK

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Area Discussion for -

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FXAK68 PAFC 151354 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 454 AM AKST Sun Dec 15 2019

ANALYSIS AND UPPER LEVELS.

A large, mature low pressure system can be seen on satellite moving slowly northwest in the western Gulf of ALaska. Its occluded front is pushing north through Kodiak and towards the southcentral coast. This low is a closed low both aloft at 500MB and at the surface. High pressure still hangs on inland north of the low. The pressure gradient between the two is creating some gusty winds in the Susitna Valley south to the Kenai Peninsula.

Out in the Bering, a weak low spins over the eastern Aleutians, causing low clouds and rain there. There is a shortwave ridge currently over the central Aleutians, providing a brief break in the weather there. This ridge is sandwiched between the low to the east and the next big system that is just approaching the western Aleutians this morning. This low is another large and occluded low moving through the north Pacific. A triple point low can be seen via satellite beginning to form as it moves into our forecast area.

MODEL DISCUSSION.

Models continue to be in good agreement. Some disagreement exists with the low center position and movement of the low that is currently in the Gulf of Alaska. However, the disagreement is not enough to make much of difference in the forecast. Therefore, we are confident in the forecast through the next few days.

AVIATION. PANC . VFR conditions and light winds will persist. Southerly winds just above the airfield should diminish enough early this morning to eliminate low level wind shear.

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

A strong low south of Kodiak Island will merge with the low near Dutch Harbor this afternoon bringing the new low center over the Alaska Peninsula. The front associated with the Kodiak low is what will have the greatest impact on Southcentral Alaska and the Gulf region today through tonight.

There is a bit of warm air associated with this front which will keep precipitation all rain at lower elevations along the gulf coast. However, the low center pulling back to the southwest will keep this warmer air from penetrating too far inland. This will also allow cooler air from inland to change precipitation to snow over the Kenai and Chugach Mountains. One of the bigger challenges for this forecast package was to determine the elevation at which the precipitation should go from rain to snow and if that will be low enough to bring the snow to the Sterling Highway in Turnagain Pass. At this time it looks like it should be mostly rain into this evening with any snow melting on contact with the ground. However, precipitation may quickly turn to snow overnight through Turnagain Pass.

By Monday, the merged low over the Alaska Peninsula from this afternoon will have weakened as it moves into the Gulf of Alaska. The front will also be much weaker, though it will remain along the north gulf coast. It looks unlikely for any significant precipitation to make it across the coastal mountains into inland areas over the next two days.

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

Active weather continues over Southwest Alaska today as a front associated with a complex low moves in from the southeast. Gusty southeasterly winds and rain are expected across the Alaska Peninsula today. Farther north over the Kuskokwim Delta, temperatures will be cold enough for snow. Current thinking is that as the front passes through later this afternoon, trace amounts of snowfall are possible for the Kuskokwim Delta Coast. As the low drifts south Sunday night into Monday, winds will weaken and precipitation will taper off. Some scattered showers of mixed precipitation are possible Monday night into Tuesday over the interior areas of Bristol Bay, otherwise general offshore flow is expected to persist through Tuesday ahead of another front that moves in from the west by Tuesday evening.

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

A 970 mb low is still centered just north of Unalaska Island. It is starting to drift southward, and will eventually phase with a second low (located south of Kodiak Island and moving northward) late this morning. The biggest forecast update made overnight was to keep the boundary of strong westerly winds just west of Dutch Harbor. It has been a challenge to pinpoint exactly where the low center will track as models have struggled to resolve this.

This newly phased low will then move over the AKPEN and eventually into the Gulf, but not before generating some gusty northerly flow over the central and eastern Aleutians this afternoon. Temperatures will generally be warm enough for rain, though a brief change to snow cannot be ruled out over the central Aleutians later today as colder air gets pulled in from the north. The next storm in the Bering arrives over the western Aleutians this afternoon, spreading in another round of southerly gales over the central Aleutians Mon night into Tue morning. As the low center tracks eastward, reaching the central Aleutians by Tue morning, colder northerly flow on the backside will bring stronger gusts to the western Aleutians for Tuesday.

MARINE (Days 3 through 5). The storm track during this period will be from the Aleutian Islands eastward to the Gulf of Alaska. High end small craft advisories to gale warnings are expected as this low pressure system moves through. Additionally, expect light to heavy freezing spray from Hooper Bay to Nunivak Island.

LONG TERM FORECAST (Days 3 through 7). The global models are in decent agreement with the longwave pattern for north Pacific and Bering through Friday December 20th. At the onset of this forecast period there are two lows, one near Kodiak and a Kamchatka low. There is a ridge axis between the two systems. There are some minor differences with the timing of two different surface lows but the forecast intensity is only a few millibars off and the forecast track is very similar. Overall, the run to run continuity with these two lows has been decent. Expect these systems to move from west to east with the first storm tracking into the Gulf of Alaska and later towards SE AK. All the while, the second storm will head into the Bering with the frontal boundary pushing across the Aleutian chain. Again, for the Anchorage metro area the chances of snow in this forecast period range from zero to slight chance.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . STORM: 119 120 130 131 GALE: 125 132 136-139 141 155 160 165 170 172-178 351 352 411 413 FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . BJB SOUTHCENTRAL ALASKA . EZ SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . KO MARINE/LONG TERM . PJS

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
ANTA2 - 9455920 - Anchorage, AK	25 mi	69 min	NE 7 G 9.9
NKTA2 - 9455760 - Nikiski, AK	66 mi	69 min	NE 19 G 24	38°F	37°F		999.3 hPa (-0.7)
SWLA2 - 9455090- Seward, AK	72 mi	75 min			44°F		997.7 hPa

Wind History for Anchorage, AK

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Anchorage, Ted Stevens Anchorage International Airport, AK	18 mi	16 min	N 0	10.00 mi	Mostly Cloudy	33°F	19°F	58%	1000.8 hPa
Anchorage, Lake Hood Seaplane Base, AK	20 mi	16 min	S 4	10.00 mi	Partly Cloudy	29°F	21°F	72%	1001.1 hPa

Link to 5 minute data for PANC

Wind History from ANC (wind in knots)

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Tide / Current Tables for Fire Island, Alaska

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Tide / Current Tables for Anchorage (Knik Arm), 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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