textproduct: Juneau

SYNOPSIS

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.../Sunday through Friday/

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

The front affecting the panhandle has moved across most of the region today, finally reaching the north later tonight to bring rain to PAHN and PAGY. Winds in these northern areas remain elevated with gusts up to 25 kts as the front passes. Rainfall will stay light through this evening with minimal impact on VSBY, allowing VFR conditions to generally prevail. Flight conditions will briefly deteriorate overnight, with periods of MVFR CIGs between 2000 and 3000 ft possible, before steadily improving from Saturday morning through the afternoon. Conditions will worsen again late Saturday as the next system arrives, offering only a brief reprieve from active weather. However, lighter rain showers will likely continue across the region throughout the day on Saturday. Forecaster confidence in significant LLWS remains low for this TAF period, though southeasterly winds aloft are expected to increase to 45 kts across the southern panhandle heading into Saturday afternoon, which could lead to moderate turbulence ahead of the approaching system.

MARINE

Outside: Fridays weather is currently being driven by a broad decaying storm force low located near 47N 135W, with the resulting surface pressure gradient drawing outflow of fresh to strong breezes out of the Panhandle. Along the coast, sea state is dominated by a trifecta of swell systems, with buoy 84 reporting stout SSW ground swell at 17 seconds being buried by southerly swell groups focused at 10 to 12 seconds. All combined, these groups are driving significant wave heights of 8 to 10 ft near the Fairweather Grounds, 12 to 14 ft near Cape Edgecumbe, and near 16 ft for waters west of Dixon.

Friday afternoon a disturbance is lifting north along the coast, with northeasterly winds breaking down and becoming southeasterly fresh to strong breezes thru the night. This wind shift foreshadows an approaching 963mb Storm Force low, which will be near 48N 140W Saturday morning. Conditions deteriorate thru Saturday becoming southeasterly gales along the coast of Prince of Wales and into Dixon; Cordova Sound and southern Clarence Strait will be particularly intense. This band of gales will lift north Sunday into Monday toward the Kenai, with conditions continuing to worsen along the northern coast.

Primary forecast challenge Friday was in the strength and direction of winds and resultant waves Sunday into Monday, with ensembles certainly suggesting southeasterly gale to strong gale force conditions for much of the eastern Gulf. For now, we continue to message winds somewhere between Gales (Force 8) and Strong Gales (Force 9), focused along much of our coast. Sunday fresh seas likely build to near 20-25 ft, becoming southwesterly Monday.

Powerful southwesterly wave energy from a decaying storm force system near 54N 154W will move toward the coast Monday into Tuesday, with buoys 83 and 84 likely reporting 15 to 20 ft significant wave heights near 13 to 15 seconds. Wont be clean, anticipate southeasterly fresh seas to ride over the swell creating rough conditions as the parent gale force low decays near the Kenai.

Active storm track continues for the Gulf next week.

Inside: Friday afternoon outflow winds are beginning to break down and become southeasterly as a system lifts along the coast. Expect Icy Strait and other east-west passages to start freshening up, with major north-south passages losing the northerly component for a few hours. The exception will be Lynn Canal where we will hold on to Strong Breezes to Near Gale Force, ebbing to moderate breezes at times, into the weekend.

By Saturday morning Clarence Strait to Sumner Strait will be see strengthening southeasterly winds, with fresh breezes becoming the dominant feel. Northerly winds will begin to get pulled out of Stephens Passage, as east-southeast winds continue to strengthen. Along and south of Sumner Strait, particularly in waters south of Gravina Island, winds will increase to gale force by Saturday late afternoon to evening.

Southeasterly Gale Force winds expand in Clarence Strait Sunday, with strong breezes to near-gale force conditions for waters along and south of Frederick Sound.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory from 6 PM Saturday to 6 AM AKST Sunday for AKZ328. Wind Advisory from 3 AM Sunday to 6 AM AKST Monday for AKZ330- 332. MARINE...Gale Warning for PKZ641-661. Small Craft Advisory for PKZ012-013-022-031-036-053-642>644-651- 652-662>664-671-672.