textproduct: Juneau

SYNOPSIS

Key Messages:

- Onshore flow bringing rain showers into Thursday. Gusty winds and moderate showers possible for northern panhandle this morning.

- High pressure will bring a bit of clearing and drier weather for southern panhandle by Thursday and central panhandle by Friday. Northern panhandle will remain cloudier with showers.

- A stronger system and weak atmospheric river will bring gusty winds, elevated seas and moderate to heavy rainfall for the weekend.

LONG TERM.../Saturday through Tuesday/

A low pressure system will enter the Gulf of Alaska this weekend, bringing gale-force winds to the outer coast along with periods of moderate to heavy rainfall associated with a weak atmospheric river. The initial wave of rain begins late Friday night into early Saturday morning as a front reaches the panhandle, impacting mainly the northern region and more so the NE Gulf coast. A stronger wave then follows, arriving by early Sunday morning. As the low slowly dissipates near south-central AK, it will meander and track multiple fronts across the panhandle. This setup, reinforced by a consistent slew of upper level troughs and divergent flow aloft, keeps precipitation in the forecast for the extended period, although overall impacts are expected to diminish gradually heading into next week. One thing of note is as the low dissipates, the pressure gradient over the northern panhandle becomes more north to south oriented, causing a potential increase in winds within Lynn Canal through Monday and Tuesday.

Impacts associated with this weekend system will initially start along the NE Gulf coast and as far south as Baranof Island, also upwind of higher elevations. From Sunday through Monday, heavier precipitation will push south across most areas, particularly targeting the Misty Fjords region. The highest confidence for 24- hour rainfall accumulations during Sunday's stronger wave ranges between 1.5 to 2.5 inches, with localized amounts reaching 4 to 5 inches over higher terrain. However, at this time there is a low (25%) chance that lower elevation areas surrounding Icy Strait, such as Juneau and Gustavus, could exceed 2.5 inches. A significant southerly jet will move along the coast Saturday, shifting southwesterly by Sunday morning and likely bringing 35 to 40 knot sustained winds from Cape Spencer north to Cape Suckling. Overnight Saturday into Sunday presents the greatest concern for elevated and gusty winds over the southern panhandle and inner channels, then trending on the decline Monday morning.

AVIATION

Showers continue moving into the panhandle through the morning hours, with VFR to MVFR conditions remaining across the area. Most areas are expected to stay largely VFR with intermittent drops to MVFR CIGs through the TAF period, with periods of gusty winds, as showers continue through the day. Brief drops to IFR CIGs are possible through the morning for parts of the northern panhandle and outer coastline, alongside some VIS drops to 3-5SM with heavier showers, but these will be short lived as an overall improving trend is expected ahead of the next round of showers.

Generally expecting the precipitation to gradually shift to stay more northward Thursday afternoon into the night. The next more organized wave of showers will push into the panhandle around 00z- 06z and move eastward past the tail end of the TAF period, primarily impacting areas from Sitka to Angoon northward and bringing marginal ceilings of 2000-3000 ft again to the northern half of the panhandle. The far southern panhandle is expected to improve to VFR and see decreased shower chances midday into Thursday night, though some isolated showers are possible through the first half of the day.

MARINE

Inner Channels: S winds of 15 to 20 kt for most areas of the inner channels north of Frederick Sound this morning. N Lynn is showing the highest winds with 25 to sometimes 30 kt overnight at Eldred Rock. These winds are expected to diminish through the day with most areas seeing 15 kt or less by this evening and then persist at that level through Friday night. N Lynn will be the exception as they could see 20 kt of wind that persists into Friday evening. Seas generally around 3 to 5 ft this morning with the highest seas in N Lynn. These seas will subside as the winds subside today.

Gulf Waters: Generally W to SW onshore flow around 10 to 15 kt remains the norm across the gulf this morning. This will not really be changing until Friday night as a new front approaches from the SW. The front will switch the wind direction to more of a SE and start to increase wind speeds as well. Gale force winds look likely by Saturday afternoon and evening along the near shore waters. Seas are generally around 5 to 7 ft with most of that being wind wave and very little swell. Not expecting much change in seas until Friday night when increasing winds from the approaching front and building SW swell starts to build seas above 10 ft.

Some isolated thunderstorm activity along the NE gulf near shore waters from Cross Sound to Yakutat Bay this morning. That is expected to diminish through the morning and should not be a concern by later Thursday afternoon.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory until 1 PM AKDT this afternoon for AKZ318. MARINE...Small Craft Advisory for PKZ012.