textproduct: Juneau

UPDATE

For the 18z TAF Issuance.

Also, an SPS has been issued for the Juneau area regarding an observed glacial lake release from Lake No Lake into the Taku River. Based upon basin estimates and current river levels, flooding is not expected. For the most up to date information, refer to the latest Special Weather Statement and check on this and other river/lake information by following links on our webpage at weather.gov/juneau.

SYNOPSIS

Key Messages:

- Onshore flow will keep the potential for light showers and drizzle the next today for the outer coast and Icy Strait corridor including Juneau.

- Weak troughing will slide through the panhandle and bring an increase potential for light rain showers for midweek.

- Slightly stronger system to possibly impact the southern panhandle by the end of the week, bringing increased rain rates.

LONG TERM.../Thursday through Saturday/

We start the period out with continued general ridging & onshore flow over the Panhandle Thursday morning. A weak shortwave will also track southeastward, moving south of the Panhandle, over Haida Gwaii, on Thursday. This low will have minimal impact on southern Panhandle weather. Northern Lynn Canal will have southeasterly winds of around 15 kt Thursday & Friday due to a tightened south to north pressure gradient that will be in place between the ridge parked over the eastern Gulf & Panhandle & lower pressure over northern British Columbia & southern Canadian Yukon region. For Friday, a weakening low will begin its push eastward through the southern Gulf of Alaska, eventually pushing through the Dixon Entrance on Saturday. This will bring with it increased chances for more substantial rainfall & southeasterly winds around 15 kt for the eastern Gulf waters, particularly for the southern Panhandle, & increased southerly winds up to around 20 kt around the Dixon Entrance & the southern half of Clarence Strait.

AVIATION...18z TAFs

A weakened area of high pressure in the Gulf of Alaska has brought a slightly weaker marine layer Tuesday morning into the northeast coast and northern panhandle. Still, the marine layer has brought ceilings as low as 800 feet at times and IFR visibilities to Yakutat, with slight improvement as of this discussion. The marine layer also pushed into Icy Strait and made it over to Gustavus, but has already begun to retreat back towards Cross Sound where FAA weathercams confirm CIGs still AoB 1500 ft. These are expected to gradually lift with daytime heating. With onshore flow, showers across the Central and Northern Panhandle (e.g. Gustavus and Juneau) could bring some ceilings around 2500 feet. Confidence in these showers dropping conditions is low, but certainly a possibility after 15Z Tuesday.

As the ridge continues to weaken in the Gulf of Alaska and a shortwave disturbance moves along the northern edge, the marine layer after 06Z Wednesday is also expected to be weaker. With breaks in the clouds, there may be some fog by early Wednesday morning, but confidence still remains low enough to not include with this TAF issuance. Fog formation will largely depend on how much clearing occurs this evening.

MARINE

Outside (Gulf and Coastal Waters): A ridge of high pressure in the Gulf of Alaska is continuing to weaken, so winds and waves are expected to continue dissipating Tuesday. Winds that have been northwesterly in the southern Gulf will become more westerly and weaken as a result of the weakening high pressure. 15-20 kt winds and seas up to 6 feet are still expected in the Gulf Tuesday, but expected to be lower Wednesday and Thursday.

Inside (Inner Channels): As the ridge of high pressure continues to weaken, expect the strongest winds in Lynn Canal, Cross Sound, and near Cape Decision to weaken through the day Tuesday. Wednesday into Thursday, a weakly organized low pressure system looks to approach Haida Gwaii. This may bring some 10-15 kt easterly winds to Dixon Entrance, but confidence in this occurring is fairly low at this time. If the low pressure system tracks slightly further north, it may impact our inner channels, but even if it does winds will likely remain under 15 kts area wide.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...None.