Marine Forecasts

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7 Day Forecast for Marine Location Near Whittier, AK

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Area Discussion for -

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FXAK68 PAFC 220037 AFDAFC

Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 437 PM AKDT Tue Mar 21 2023

ANALYSIS AND UPPER LEVELS.

A broad long-wave trough with embedded shortwaves extends from the Kamchatka Peninsula into Southcentral Alaska. The two shortwaves of note to the weather today exist just south of the Prince William Sound, with a stronger feature moving over the eastern Aleutians and Alaska Peninsula this afternoon. The northern Gulf low has been sending bands of light snow into the coast today, but is rapidly weakening. The stronger western low continues to intensify as it moves east, with strong winds and snow impacting the eastern Aleutians and Alaska Peninsula this afternoon. To the west of the low, cold air advection in a westerly flow regime has created a broad area of snow showers.

MODEL DISCUSSION.

Models are in good synoptic agreement through 24 hours before they begin to diverge. The most notable difference is in the low track starting at 12Z Wednesday as a compact low moves over or just south of Kodiak Island. This track will have implications for the snow and blowing snow forecast for the western and northern sides of the Island at the system tracks to the east. There are also some differences in the speed as the front lifts north through the Gulf Coast and Prince William Sound, which will have an impact on snow totals.

AVIATION.

PANC . VFR conditions will persist. Gusty northerlies will develop in the morning Wednesday in response to a low moving into the Gulf.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Tonight through Friday) .

Snow showers are ongoing across Eastern Prince William Sound down to Kayak Island this afternoon. What remains of an occluded low and front will push inland of the coast through this evening and ultimately dissipate. The rest of Southcentral has enjoyed largely clear or partly cloudy conditions from the Susitna Valley into the Copper River Basin while under a transient ridge of high pressure. On satellite the next snow maker is quickly approaching Kodiak Island from the south. A triple point low is in the process of forming south of the Alaska Peninsula and will move over Kodiak Island tonight through the morning hours on Wednesday. A threat for snow and blowing snow is expected as the low departs to the east of the region, with increasing northwesterly winds developing over the Shelikof Strait. Locations could see anywhere from 3 to 5 inches of snow coincident with gusts of up to 50 mph. Despite warmer temperatures, visibilities would likely be reduced to one half mile or less at times, especially for Kodiak Island's western coastline. A winter storm watch is currently in effect for the area, as some questions do remain with how far north the surface low will lift across Kodiak Island before shifting east and into the Gulf. While not currently forecast, any further northward movement of the low would bring increased snow amounts and wind to the city of Kodiak and potentially into Kachemak Bay. However, it should be noted that models have been trending the opposite direction, with the surface low remaining further south and east of Kodiak City.

Low pressure center then continues eastward into the offshore regions of the Gulf while its front moves into the Kenai Peninsula and Prince William Sound through the morning hours on Wednesday. A blizzard warning is in effect for Western Prince William Sound and the Eastern Kenai Peninsula. Easterly winds gusting into the 40's and 50's are anticipated on top of moderate to heavy snow. Areas from Whittier into Portage into Turnagain Pass could see a foot or more of snow through Wednesday. Locations further south along the Seward Highway are expected to see more modest snow amounts of 6 to 12 inches, while locations closer to Girdwood may see snow amounts of 5 to 7 inches. In addition to snow winds will be active through the Eastern Turnagain Arm and across the Seward Highway Corridor. Winds gusting as high as 50 mph could significantly reduce visibility down to one quarter of a mile or less, which will make for hazardous driving conditions for those on their morning commute on Wednesday.

For Thursday, snow showers are expected to linger over the eastern mountain faces as the Gulf low maintains elevated southeasterly flow into the Gulf coast. Strong easterly flow aloft should downslope much of the precipitation out for locations further inland. The Anchorage Bowl may see a brief bout of light snow as winds relax on the tail-end of the departing Gulf low. Attention then turns to Friday where a shortwave trough digging into Southcentral may see snow chances increase again from the Susitna Valley into the Copper River Basin.

SHORT TERM FORECAST SOUTHWEST ALASKA (through Friday morning). A low pressure system traversing the Alaska Peninsula and strengthening Tuesday evening will bring active weather to the area through early Thursday. Snow will overspread the Alaska Peninsula Tuesday evening as winds rapidly increase across the area. Some snow will spread over into the Greater Bristol Bay area, but the majority will be along the Peninsula. In general expect most areas to be in the 1-3 inch range with some areas along the Alaska Peninsula in the 3-6 inch range. Blowing snow is also an issue mainly from Pilot Point through Naknek, but there may be enough open water within the ice pack to mitigate some of the blowing snow as well as keeping temperatures a tick warmer. A deformation band looks to form over Dillingham through Pilot Point and progress northeastward through late Wednesday bringing some light accumulating snow to most areas. A late season colder air mass comes onto the mainland behind this system for the remainder of the week. Thursday looks to bring a quick shot of snow as a low forms near the ice edge and move toward the Y-K Delta.

SHORT TERM FORECAST BERING SEA/ALEUTIANS (through Friday morning). A low transiting across the Alaska Peninsula into the Gulf of Alaska is spreading a late-season arctic air mass over the Bering which will bring widespread gales and snow showers through Wednesday. Model guidance is hinting at a possible polar/hybrid type low to form along the ice edge. These are usually compact with a small but intense wind field, usually gales or greater. The amount of upper dynamics should push this eastward toward the mainland quicker than would normally happen. A stronger western Bering system will bring a front and southerly winds on Friday, likely gales with the possibility for storms.

.LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)

A transient, but amplified ridge will build into Southcentral Saturday bringing quieter weather through Sunday before another Bering Sea front approaches in the latter half of Sunday and into Monday. This creates another problem with possible precipitation for Southcentral heading into the week due to the development of a possible surface low in the Gulf. Models have been struggling to define what exact impacts this aforementioned low will have. Out west, conditions along the southern half of Bristol Bay and the Alaska Peninsula should remain fairly quiet through Saturday. Northern parts of Bristol Bay into the Kuskokwim Delta region could get clipped by a Bering low pressure system's warm- front the latter half of Friday into the day on Saturday, which paves the way for light precipitation chances. The cold- front of this Bering low will track into the western Bering and western Aleutians Friday making it to the Southwest coast by Saturday night into Sunday morning. Accompanying this front will be gale- force winds with possible storm-force gusts, especially for the western Aleutians. As the front progresses eastward throughout the central and eastern Bering, winds will weaken mostly to low- end gales to high-end small craft through Sunday morning. Southwest looks to become unsettled late Saturday night into the day on Monday as the front will cross the southern mainland then. There are still a few timing differences regarding the progression of the front through Southwest. However, the progressive pattern looks to continue with no real sustained breaks in activity.

AFC WATCHES/WARNINGS/ADVISORIES. PUBLIC . Blizzard Warning 125. Winter Storm Watch 171. MARINE . Storm Warning 734 751 755. Gale Warning 710 711 712 715 716 724 725 726 730 731 733 732 738 742 750 752 753 754 756 757 758 759 770 772 771 773 774 775 776 777 778 780 781 782 783 784 766 760 761 762 764 411-414 351-352. Heavy Freezing Spray Warning 760 761 762 764 767. FIRE WEATHER . NONE.



SYNOPSIS AND MODEL DISCUSSION . CJ SOUTHCENTRAL ALASKA . BL SOUTHWEST ALASKA/BERING SEA/ALEUTIANS . ML LONG TERM . NS

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	inHg	DewPt
46081 - Western Prince William Sound	13 mi	82 min	ENE 18G23	37°F		2 ft	29.44	33°F
WIXA2	29 mi	37 min	NE 22G35	35°F			29.38
BLIA2 - Bligh Reef Light, AK	70 mi	42 min	E 9.9G12	36°F			29.53
SWLA2 - 9455090- Seward, AK	75 mi	60 min			39°F		29.36

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Airport Reports

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Airport	Dist	Age	Wind kt	Vis	Sky	Weather	Temp	DewPt	RH	inHg
PATO	0 sm	18 min	E 19G43	1/2 sm	Overcast	Lt Snow	36°F	30°F	81%	29.35

Link to 5 minute data for PATO

Wind History from ATO (wind in knots)

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Tide / Current Tables for Applegate Island, Alaska

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