textproduct: Juneau

SYNOPSIS

Key Messages:

- A weak disturbance will slide south through SEAK Sunday night through Monday, bringing a chance of showers.

- Quiet weather returns for Tuesday through Thursday, with more sun and dry conditions expected. Northerly outflow winds expected to increase through the inner channels and outer coastal waters.

- A return to a wetter pattern expected by late week into next weekend.

LONG TERM.../Wednesday through Friday/

Confidence in the long term forecast is fairly high, in that there is great agreement on a large high being situated over the Gulf of Alaska through almost the end of the workweek. This will lead to mostly light winds, with the exception of Wednesday. As a low recedes south of Haida Gwaii further towards British Columbia and a tongue of high pressure comes back south to the Gulf from south- central Alaska, gradient driven winds will be stronger, but weaken over time into Thursday for the upper inner channels, such as Lynn Canal and Stephens Passage.

The next pattern change will come with the end of the work week, as a front moves toward the area later Friday into Saturday as the high breaks down. Guidance has slowed the onset of impacts with this latter system from run-to-run. At this length of forecast, conjecturing at exact impacts is a fool's errand, but elevated winds for most of the panhandle, as well as the next bout of notable rainfall are expected. An early estimate of rain onset would be Friday PM for the northern panhandle.

AVIATION.../through 0Z Tuesday/

VFR conditions continue to prevail, with the exception of PAYA which is seeing the marine layer build as the high pressure in the gulf shifts southeast. Misty conditions have reduced visibilities in Yakutat With broken CIGs sitting around 1,500ft. A scattered layer has been transitioning to broken at about 500ft through the daytime hours and is expected to build again overnight. As the high pressure breaks apart, a weak shortwave is expected to move across the area late tonight into early Monday morning. This bringing low chances of rain to outer coastal sites and increased cloud cover across the panhandle. Rain is expected as early as 9Z and as late as 12Z, with mid level broken to overcast decks moving into the southern panhandle between 12 and 15Z. This first wave of energy is likely not strong enough to reach the inner communities, but a secondary weakening front could increase rain chances across the panhandle through the day Monday. Wind is likely to remain light and variable through the period with no other forecast concerns.

MARINE

Outside (Gulf and Coastal Waters): High pressure over the western Gulf of Alaska will gradually build and shift eastward Sunday through Tuesday, peaking around 1036mb near 50N, 150W. This will drive predominantly NW'ly winds across the Gulf coast and offshore zones. A low marine layer is expected to push in along the NE gulf coast overnight, though will retreat Monday morning. Winds are expected to strengthen to fresh to strong breezes from Cape Decision southward to Dixon Entrance early Monday morning, expanding north to Cape Fairweather and Cape Spencer by midday Monday. These elevated coastal winds will likely persist through late Tuesday before diminishing Wednesday, with Dixon Entrance easing last. Seas will build alongside the winds, reaching 8 to 10 ft south of Cape Edgecumbe and 6 to 8 ft to the north.

Inside (Inner Channels): Light and variable winds persist this afternoon and into the day Monday. Patchy fog formation possible within inner channels again tomorrow morning. Outflow winds will strengthen overnight Monday into Tuesday as a weak low slides south down the panhandle, developing an inverted trough with its axis stretching from the southern panhandle toward Yakutat. This feature will tighten the pressure gradient between the high pressure over the Gulf and the interior high over the Yukon, primarily favoring N-S oriented inner channels. Winds will pick up early Tuesday morning, beginning in the north and spreading southward. Lynn Canal will experience the initial increase, followed by Chatham Strait, southern Stephens Passage, Frederick Sound, and eventually Clarence Strait by late morning. Winds in these areas are likely to reach Small Craft Advisory speeds by early Tuesday morning, with near gale force sustained winds possible in Lynn Canal. Model guidance continues to trend stronger indicating likely gale force gusts in Lynn Canal during this time. Wave heights will also increase, noting 4 to 6 ft in unsheltered locations. Elevated winds across the region will persist through the day Tuesday before diminishing midweek.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ641>643-661>664-671-672.