textproduct: Juneau

SYNOPSIS

Key Messages:

- A low pressure system pushes into SE AK Saturday bringing increased winds and precipitation.

- Outflow pattern allows for drier and colder weather Sunday into next week.

- The outflow pattern will bring strong winds over northern SE AK. These strong winds with colder temperatures will create moderate freezing spray over northern inner channels.

LONG TERM

Over the week the primary threat continues to be outflow conditions, freezing spray, and very cold temperatures as cold arctic air infiltrates the panhandle, bringing a sudden return to true winter. Touching on wind first, we remain highly confident that we will see northerly winds of at least 25 to 30 knots spread across the northern inner channels by Monday, with a mountain wave event for downtown Juneau bringing frequent gusts of 40 to 60 mph. The main question is the potential of gale, to strong gale, force outflow winds ebbing and flowing through the week, which has serious implications on mariners safely navigating the inside. For now, the published forecast has strong gale force conditions in Lynn Monday into Tuesday. Guidance continues to slightly relax the north-south pressure gradient mid-week, which would result in winds diminishing to near-gale force conditions, perhaps even as low as strong breezes. However, do not let this catch you off guard. The winds will increase again to at least gales sometime by the end of the week, perhaps into the weekend, as a strong north- south pressure gradient builds back. Freezing spray really becomes a threat Monday, with freezing spray pumping through the inside all week. Heaviest freezing spray in Lynn Canal, Taiya Inlet, four corners area, Stikine Inlet, and Unuk River Inlet.

It will become very cold, below 0F in the north, single digits in the Icy Strait corridor, and teens to low 20Fs in the central and south. Wednesday night there is some signal that a shortwave trough will rotate around a stout ridge in the Pacific, perhaps bringing some snow to the region Thursday. Guidance usually struggles with a strong ridge over the region, we approach cautiously.

AVIATION

Conditions across the panhandle this afternoon continue to be VFR to MVFR with CIGs being the main issue. Some locations continue to bounce between IFR and VFR due to cloud decks fluctuating. Conditions are expected to deteriorate later this evening as cloud cover increases with the next system approaching the area. With this next system, CIGs are expected to drop before VIS drops due to precipitation falling across the area. For the northern panhandle, this is expected to primarily be SN which will aid in restricting VIS down to MVFR to IFR. Farther south, RA is expected to be the primary precip with MVFR conditions; although some possible mixing may happen, especially for places like Petersburg and Wrangell. After this system moves through tomorrow, conditions should start to slowly improve from north to south as outflow slowly takes over. LLWS continues to not be a concern at this time but will need to be watched for the latter periods as outflow conditions strengthen.

MARINE

Inside (Inner Channels): For most part Saturday night are starting with the light winds up to 15 kt. Gusty winds starting near Skagway and the westerly wind into Cross Sound and near Cape Decision. Brief increase in speed as the move more into the panhandle, however, as it dives south, building high pressure in northwest Canada will increase the northerly outflow pattern so winds down Lynn Canal increasing to Gale force by Sunday night. The continued outflow pattern will allow fully developed seas to form in the Lynn Canal, Chatham Strait, and Stephens Passage. Starting Sunday night into Monday, freezing spray will develop over the more northern inner channels.

Outside (Gulf and Coastal Waters): Surface low moves into the Northeast gulf Saturday afternoon and then dives southeast along the coast. As the moves southeast, the west flow near the coast coast, shifts Southeast to south, and then to the NW, and increasing. An upper level feature will lead to a continued NNW flow pattern across the majority of the gulf to a brisk flow of 25 to 35 kt Sunday into the start of the week.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...High Wind Watch from late Sunday night through Monday afternoon for AKZ325. MARINE...Small Craft Advisory for PKZ022-641>644-661>664-671-672.