textproduct: Juneau

SYNOPSIS

Key Messages:

-Lingering rain showers, heaviest over the northern half of the area, through the remainder of the week

-A weak front moves across the north on Friday, with a low moving across south/central SE AK beginning Friday night.

LONG TERM

The polar jet remains impressive for this time of year, steering an active storm track along the Aleutians. Digging into long range guidance, all ensembles continue to trend to a deeper trough by Sunday as a system undercuts the Gulf, with increasing confidence in at least southerly gale force conditions for Hecate Strait. The primary challenge this afternoon is the potential northward expansion of gales into Dixon but there exists substantial variation in location and intensity of the forecasted low. For now, the published forecast will continue to highlight at least near-gale force southeast winds for Dixon Entrance by Sunday afternoon with peak winds overnight into early Monday. Most concern for mariners along and south of Sumner Strait. As this first system pushes into the western sea board Sunday, an impressive storm force low will move along the Aleutians, generating very large southwesterly swell which move into our coast by Tuesday/Wednesday. Some wave guidance suggests 12 to 14 ft near 18 to 20 seconds out of the near 230 to 240 degrees true. Mariners navigating along our coast and ocean entrances should monitor the forecast moving through the weekend and be aware of this threat.

Touching on rain potential and the holiday weekend, rain will largely fall apart Sunday night for the north and central Panhandle (areas north of Frederick Sound), with Sundays low moving into Haida Gwaii responsible for some rain in the south. Simply put, not so bad for the north and central Panhandle. Likely wet and windy for the south. Later in the week the strong system along the Aleutians will steer more moisture into the Gulf and Southeast, but at this time overall QPF amounts remain within ranges of what we typically experience this time of year. Would anticipate a wetter week next week.

AVIATION

A frontal passage will move south across the panhandle late tonight through early morning, followed by ridging and potential fog with no LLWS concerns expected. Northern sites will likely face intensified winds and variable flight categories as the front moves through. Yakutat is forecasted to see persistent rain, a northerly wind shift gusting to 20kts, and late morning deterioration to low MVFR/IFR. PAGY and PAHN anticipate southerly gusts (25-30kts) and morning showers with MVFR CIGs. Within the Icy Strait corridor, PAJN and PAGS will see lower CIGs, localized fog, and early rain, with PAGS potentially dropping to 1500ft. CIGs along the outer coast should lower to 1500ft by early morning as well, with rain and gusts moving in the front around 15Z. Southern sites will transition from VFR to MVFR around 06Z as showers start to arrive, with steadier rain by 18Z. These sites will be mostly MVFR with possible IFR CIGs and VISBYs due to the marine layer and showers are expected to move in late afternoon.

MARINE

Inside Waters (Inner Channels): Through Friday morning, for northern Lynn Canal, expect southerly winds to around 25 kt & significant wave heights to around 5 ft due to a tightened pressure gradient between a low over the Canadian Yukon & ridging to the south. These winds will diminish to 15 kt or less with waves of 3 ft or less with a more relaxed pressure gradient by the weekend & into early next week. For the rest of the Inner Channels, primarily expect winds of less than 20 kt & seas of around 4 ft or less through the weekend & into early next week.

Outside Waters (Eastern Gulf of Alaska): A weak frontal system will push through the eastern gulf tonight through Friday evening, increasing sustained winds over that entire region to around 20 kt. Winds will increase up to around 25 kt for an area between Icy Bay & Cape St. Elias from the shoreline out to about 20 nm offshore late tonight into Friday afternoon associated with a barrier jet as the aforementioned front pushes through. Significant wave heights should stay between 6 & 10 ft through Friday night with the highest values to the south. Winds increase to around 25 kt for the SE gulf for the latter half of the weekend into next week as a low pressure system marches toward the southern panhandle, increasing seas to between 7 & 11 ft over that area for that timeframe.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory until 1 AM AKDT Friday for AKZ318. MARINE...Small Craft Advisory for PKZ012-641>643-652-661>664-671-672.