Marine Forecasts

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7 Day Forecast for Marine Location Near Homer, AK

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Area Discussion for -

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FXAK68 PAFC 220035 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 402 PM AKDT Mon Sep 21 2020

ANALYSIS AND UPPER LEVELS.

This afternoon, a near full latitude trough extended in a negative tilt from eastern Siberia, through the Alaska Peninsula, into the North Pacific. Several pieces of energy are seen in the satellite data diving into this trough from the north and then rotating around the low. This is helping foster scattered shower development across the Alaska Peninsula, Southwest Alaska, and into the Gulf and Southcentral.

MODEL DISCUSSION.

Today's numerical runs show good agreement at the surface and aloft with the low transitioning from the Southern Bering into the Gulf, but then differences arise in the 60-84 hour period as additional shortwave energy aloft dives into the backside of the trough the parent low is currently in. As this additional energy arrives, new surface cyclogenesis commences and pivot in a counter clockwise fashion, as the two lows rotate around one another (Fujiwhara effect).

At what strength and what location remains the question, as the Canadian is deepest at 977 mb by day 3 (Thursday) just outside of Price William Sound, and the GFS weakest/furthest south across the Southern Gulf. The NAM and ECMWF are in between these models in position and strength. This adds some uncertainty to wind field orientation, strength, and precipitation amounts.

AVIATION.

PANC . Light and variable winds will prevail at the terminal through the forecast period. The main challenge through, as low stratus from the Cook Inlet moved overhead earlier, and it's still lurking around with it being reported at 500 feet in a scattered variety. How long this will continue is the main question at this time.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Monday night through Thursday) .

A frontal system will continue to move north from Kodiak Island and across the Northern Gulf, bringing Gale to Storm force winds through Wednesday. Otherwise, a series of lows will rotate across the Gulf and past Kodiak Island, keeping coastal areas quite wet through the period. Expect as much as 2 to 4 inches of rain from western Prince William Sound to Kodiak Island. Some rain will spill over the Chugach Mtns into parts of the southern Copper River Basin, but most inland areas of Southcentral will generally be dry with a few showers possible this evening.

The main upper trough and low will begin to exit eastward on Wednesday, which will allow winds to diminish across the Gulf. However, it does look like one more surface low will develop and track westward across the central Gulf. There is quite a bit of uncertainty in the track and strength of this low, but it does look like it will stay out over the Gulf. Some of the moisture with this low will advect toward Southcentral, so expect increasing chances of rain for inland areas Wednesday through Thursday.

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

Gusty northeasterly winds will gradually turn more northerly through mid-week with both high and low temperatures trending downward to the mid 40s and mid 30s, respectively. While a few showers are possible along the immediate Kuskokwim Delta coast and near the Alaska Range, much of the area should remain dry through Thursday in the cool, dry northerly flow.

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

A cool, northwesterly flow will persist through Wednesday, generally east of Unalaska between a low in the Gulf and a ridge over the western Bering. Gusty winds are expected through this evening, particularity out of gaps on the Pacific side of the central/eastern Aleutians. Scattered showers will persist through Tuesday and will gradually become more isolated thereafter as the air mass becomes drier. Winds will likewise diminish as the aforementioned low weakens and moves farther east into the Gulf.

MARINE (Days 3 through 5/Thursday through Saturday).

Gulf of Alaska: There is moderate confidence that the broad low pressure system in the western Gulf will break down through Friday afternoon. The GFS deterministic model has the low remaining in the Gulf longer than other models but winds and waves should remain at or below small craft criteria through Friday. On Saturday there is moderate to high confidence that a Gale force low will move into the Gulf from the North Pacific. Model spread of the low center pressure ranges from 975 mb to 986 mb. There is low confidence in the location of maximum winds at this time due to high model spread on the east/west location of the low center.

Bering Sea/Aleutian Chain: There is high confidence that winds and waves will be mostly calm through the region on Thursday. On Friday morning a Polar trough will bring moderate (<34 kts) northerly winds through the Bering Strait and into the Bering Sea by Friday evening. On Saturday a weak northerly shortwave and surface low may create winds up to gale force over the western Bering. Confidence in winds reaching gale force on Saturday is moderate.

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

Synoptically, a broad longwave trough is expected to persist over the region with the jet centered between the 40th and 50th parallel. This should continue the fall pattern of rainy weather for most of the region, but primarily the Bering Sea, AKPEN and Gulf coast. Late Friday and Saturday will likely be the wettest for the Alaska Mainland as a moderately strong storm moves into the Gulf. The broad nature of this system, extending from Bristol Bay to Southeast Alaska will allow for upper level shortwaves to bring moisture and rain into the Alaska interior. Model guidance has come to better agreement in regards to this low, with the low center moving into the Prince William Sound Sunday morning. By Monday, model guidance begins to considerably differ once again, with the GFS bringing the storm back into the Gulf and the EC pushing it into Bristol Bay.

Northerly flow on the backside of the aforementioned low is expected to bring a polar airmass over the Bering on Friday. A series of shortwaves may help provide lift needed for showers over the western Bering and Aleutian Chain through the forecast period. Simultaneous ridging over the Kamchatka Peninsula will help to bring warmer air in from the Western Pacific, thus setting the stage for the next baroclinic storm in the Western Bering. Models are in excellent agreement that a Kamchatka low will form Monday morning with the front reaching the Western Aleutians on Monday afternoon.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . NONE. MARINE . Storm Warning 119 120 131. Gale Warning 130 138 139 150 155 170 171 172 174 351. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . PD SOUTHCENTRAL ALASKA . RC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . AP MARINE/LONG TERM . CJ

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
HMRA2 - Kachemak Bay Reserve, AK	7 mi	80 min	NE 13	52°F			993 hPa	44°F
HMSA2	7 mi	28 min	NE 8.9 G 14	53°F			991.9 hPa	43°F
OVIA2 - 9455500 - Seldovia, AK	17 mi	56 min			52°F		994.2 hPa
FILA2 - Flat Island Light, AK	32 mi	50 min	NNE 16 G 18	51°F			994.1 hPa (-0.7)	45°F
AMAA2 - East Amatuli Light, AK	55 mi	50 min	NNE 28 G 32	53°F			991.9 hPa (-0.5)	47°F

Wind History for Nikiski, AK

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NE12

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NE21 G26

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SE6

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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	16 mi	57 min	N 0	10.00 mi	Overcast	48°F	46°F	96%	994.6 hPa

Link to 5 minute data for PAHO

Wind History from AHO (wind in knots)

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Calm

Calm

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Tide / Current Tables for Homer, Alaska (2)

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Tide / Current Tables for Sadie Cove, Kachemak Bay, 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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