textproduct: Juneau

SYNOPSIS

Key Messages:

-Moderate to heavy snow spreading over the panhandle Wednesday night into Thursday with heaviest amounts expected along the outer coast

-Northerly outflow intensifies as snow exits the region Friday, with strong gales developing for the northern inner channels by late Friday night ushering in colder temperatures for the weekend

LONG TERM

Friday the longwave trough begins to dig south, forming into a closed low along the western seaboard over the weekend. As this feature transits south, a very tight surface pressure gradient forms again between an arctic high in Canada and the relative warm waters of the Gulf, increasing the confidence that strong gale force outflow winds return for many inner channels through the weekend with the associated colder weather and freezing spray. For Juneau, a Taku wind event is becoming likely Saturday, driving gusts higher than 60 mph, with strong gusty winds persisting through the weekend.

Monday, outflow diminishes again as the Yukon high weakens and a new weather system moves in from the W. The possibility of precipitation returns for most areas by Tuesday with most of the areas likely still cold enough for it to be mostly snow.

AVIATION

A ridge of high pressure over AK panhandle will slowly weaken through the rest of tonight as a low pressure system over Prince William Sound approaches then northern portions of SE AK. While the region is currently experiencing VFR conditions and some gusty winds that will continue to ease through the evening hours. After midnight ceilings will begin to lower to more MVFR conditions as the frontal system approaches from the west towards Yakuatat and then continuing east over the panhandle during the morning and early afternoon hours tomorrow. As the front moves through snow will bring visibility down to less than 3SM. After approximately 10am tomorrow preciptiation type for the Yakutat area will begin to transition to a more rain snow mix as the low moves over.

MARINE

Outside (Gulf and Coastal waters): Winds are below 20 knots for areas north of Cape Edgecumbe, with northerly winds of 15 to 20 knots as you move south toward Dixon entrance. Fresh seas are being generated from these winds, with buoy 46206 reporting significant heights near 8 ft at 7 seconds. The rest of the coast is seeing SW swell near 3 ft at 12 seconds. Wednesday night westerly winds build in response to a wave moving into the gulf, with moderate to strong breezes being felt by Thursday night and WNW gale force impacting the central gulf, bringing significant heights of 10 to 12 ft to our coast, near 20 ft for the central gulf, by Friday. Friday into the weekend outflow winds impact our region; mariners should anticipate strong gale force northerly winds along major bays/inlets along the coast, with storm force NE winds likely near Dangerous River, bringing freezing spray and NE fresh seas.

Inside(Inner Channels): Winds continue to diminish Wednesday night as the surface pressure gradient relaxes, a welcome break from the intense outflow conditions impacting the region over the last 48 hours. Anticipate winds largely less than 20 knots Thursday as snow moves across the Panhandle. Thursday night, winds begin to increase as a low transits south, with outflow winds building Friday. Mariners in Yakutat Bay will see gale force early Friday morning, with storm force in upper bay.

Expect gale force northerly winds in Lynn Canal by Friday afternoon and Taku Inlet, spreading south through the night. Gale to strong gale force will impact most areas along and north of Sumner Strait, with major inlets like the Stikine and Unuk seeing higher winds. Confidence is increasing for storm force conditions Sunday in Lynn Canal. These winds, along with cold temperatures, will generate large seas and freezing spray, complicating transits through our passages.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Winter Storm Warning from midnight tonight to 3 AM AKST Friday for AKZ317. Wind Advisory until 3 PM AKST this afternoon for AKZ318. Winter Weather Advisory from 3 AM to 9 PM AKST Thursday for AKZ320-321-324-325. Winter Storm Warning from 3 AM Thursday to 6 AM AKST Friday for AKZ322. Winter Storm Warning from 6 AM Thursday to 9 AM AKST Friday for AKZ323. Winter Weather Advisory from noon Thursday to 6 AM AKST Friday for AKZ326-327-329. Winter Storm Warning from noon Thursday to 9 AM AKST Friday for AKZ328. Winter Weather Advisory from 6 PM Thursday to 9 AM AKST Friday for AKZ330-332. MARINE...Small Craft Advisory for PKZ031-661-663-664-671-672.