textproduct: Juneau

UPDATE

Update at 2100 AKST for aviation and long term discussion.

SYNOPSIS

Active fall storm track to continue with systems every 2 to 3 days, either moving through or around the edge of the panhandle. Friday's system is a near miss to the south. The Sunday system is a low curling into the southeast corner of the Gulf of Alaska and then to the northern gulf. The Sunday low will likely have some significant winds for the marine zones and possibly over the land areas of the southern panhandle.

Key Messages:

- Low and frontal band moving into British Columbia Coastline just north of Vancouver Island Friday.

- The next big low (roughly in the mid 960mb range) to impact Southeast Alaska Sunday as it and the associated frontal band moves through the SE Gulf of Alaska on Sunday.

LONG TERM

A fairly active pattern will continue for Southeast Alaska through the long term period. A significant low pressure system moving northward toward the area late Saturday and into Sunday. This system currently appears to be the most worthy particularly for the southern panhandle, with increasing forecast confidence in strong winds (40-50mph) for areas south of Port Alexander. The uncertainty on the exact strength of this system is due to how quickly and where the low that moves through on Friday dies out. If the Friday low weakens and dies out over by PWS before the late Saturday-Sunday system moves in then the southern panhandle could see sustained SE winds closer to the 45-55mph. In addition to wind this low will bring a round of rain and high elevations snow (including the Haines and Klondike Highways). This low will continue to move north and then west toward Prince William Sound late Sunday and into Monday and weaken. Multiple shortwaves after this system will move through the area each brining their own bouts of preciptiation. What is more noteworthy during this period is the gradual lowering of snow levels through the rest of the week. Current guidance even has snow levels dropping down to around 1000 feet with for areas along the Coastal Range and the northern Panhandle late next week. As a result if precipitation were to be also moving through due to a shortwave disturbance there would be the potential for it to fall as snow or rain/snow mix at sea level. All that said there is still great uncertainty when it comes to that time frame and multiple things would have to align, but it is certainly something to watch.

AVIATION.../Through 06z Saturday/

This evening, some locations have seen very short periods of either lowered ceilings or visibilities. Using satellite imagery, these times look to be during very short breaks in the clouds. Otherwise, flying conditions remain primarily VFR with high level broken to overcast skies AoA 4000 ft. Cloud cover looks to remain over the area as the next low pressure system slowly moves eastward, eventually moving northward. As this low moves northward, periods of rain will once again move across the panhandle. As rain passes, there may be short periods of MVFR ceilings around 2000 to 3000 ft, but forecast confidence remains high that ceilings and visibilities will remain VFR. Winds will also be something to watch as the low pressure system moves northward. This will cause northerly winds to strengthen, especially near Haines and Skagway with wind gusts around 30 kts starting early Friday morning.

MARINE

Outside: Buoy 46082 (Cape Suckling) was ripped from its mooring and set adrift during the powerful storm Monday Nov 9. Data is no longer available for this sensor package.

An active storm track continues to impact the Gulf, with a series of Storm Force lows bringing a complex wind and wave forecast through the weekend into next week. Expect the best conditions through Thursday afternoon as winds and seas relax a bit, likely trending to near 7 to 9 ft along the northern coast, to 8 to 10 ft for the Alexander Archipelago. Friday, the first Storm Force low (currently near 50N 148W) will continue to move east toward the PNW, which will serve up SSW swell group, buried by a dominant southerly swell group. Friday, expect significant wave heights near 8 to 10 ft for the northern coast, becoming 11 to 13 ft for areas near Cape Edgecumbe, and near 14 to 16 ft for Dixon Entrance. Mariners planning to operate with 15nm of our coast should be aware of the SSW ground swell focused near 15 to 17 seconds riding under southerly swell, which could penetrate into protected westerly bays and inlets along the Chichagof, Baranof, and Prince of Wales coast.

To further complicate conditions Friday, outflow of strong breezes will be coming out of Cross Sound and Chatham Strait Ocean entrances helping to increase wave height during opposing tidal cycles. Our wave height forecast does not take into consideration ebbing and flooding tides. Friday, watch that southerly wave group against a northerly wind and flooding tide, particularly in southern Chatham Strait and western Sumner Strait.

Saturday swell begins to diminish slightly but east to southeast winds will increase as a secondary Storm Force low moves north toward Haida Gwaii. Expect strong breezes to near-gale force conditions to become prevalent over much of the Alexander Archipelago coast and eastern Gulf, with areas in the direct lee of prominent coastal landmasses seeing some protection from building fresh seas. Gales build Sunday in Dixon and west of Prince of Wales, lifting north by Sunday night. Expect large and confused seas out of the ESE Sunday, becoming southerly by Sunday night, reaching near 15 to 20 ft for much of the eastern Gulf and moving toward the northern coast. Waves could be higher depending on strength of wind Sunday into Monday. On the backside of this system Tuesday, prominent westerly wave energy arrives along our coast.

Inside: Thursday continues to be the lightest wind day, relative to this active week, particularly in the north. A wave Thursday morning moved north over the central and southern regions freshening up the SE winds of fresh breezes for waters south of Icy Strait. Camera images and weather sensors on the mighty tug, Western Mariner (data courtesy of the Marine Exchange of Alaska) highlighted easterly winds of moderate to fresh breezes bringing a choppy sea state as she moved toward Kake and then east thru Frederick.

By Thursday evening winds should be beginning to show a signal for switching, becoming more northerly overnight. Current forecast favors fresh breezes for major north-south passages like Chatham Strait and Stephens by Friday morning, with several hours of strong breezes in Lynn Canal. For Chatham Strait and Stephens Passage, strongest winds are likely near 4am AKST Friday to about 12pm AKST Friday, with northerly winds beginning to shift to more easterly late Friday afternoon, increasing easterly wind for Icy Strait and Cross Sound. Per usual, Lynn Canal holds on to northerly winds of fresh to strong breezes through the weekend; however, expect winds to ebb to moderate breezes at times.

Saturday easterly winds build across the central and southern inner channels, becoming gales in Clarence Strait by late Saturday. Sunday into Monday looks particularly dangerous for waters along and south of Frederick Sound, where strong-gale force conditions are a possibility. With that said, there still exists large spread in various model guidance. Stay tuned to the marine forecast as we track the evolution of this system.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-022-033-053-641>644-651-652- 661>664-671-672.