textproduct: Juneau

SYNOPSIS

Key Messages:

- Showers will steadily diminish Wednesday, with clearing skies expected from North to South Thursday into Friday

- A system may clip part of the southern panhandle Thursday, but should move out of the area fairly quickly.

- Clear skies expected to persist into the weekend, with precipitation potentially moving back into the northeastern gulf coast Sunday

LONG TERM

/ Thursday to Monday / Aloft the steering levels of the atmosphere has a long wave trough finally being ejected from the gulf late Thursday to Friday, followed by a sharper moderate- high amplitude ridge that reaches near to arctic shores. Ridge will slide east of the panhandle by late Sunday, as the Large Bering Sea low from the western Bering Sea weakens but shift to the eastern portion of the Bering. With the ridge axis east of the area, noticed a pair of short waves, one Sunday evening pushing through the panhandle over the ridge top, and second one which may be slightly stronger for the Monday time frame.

So what does this mean weather wise for Southeast... showers from the midweek into Thursday, tapering off/ending as improvements Friday - early Saturday period due to the ridge moving through and clearing weather out. After the ridge slides by rain will start to push back in into the NE Gulf then Northern panhandle late Saturday to Sunday. Models beginning to come to agreement of fairly organized from to push through the eastern gulf Sunday to Monday. A secondary low that formed on the front towards the Yakutat Pocket and the front trailing south then southwest, with likely another trailing low on the front to run along and slowing it down to impact the southern panhandle most likely the hardest. Will watch how models adjust over the next few runs.

In short longer range is wet, dry break Friday-Saturday and then wet into next week. Temperature-wise at or just below normal values, with higher elevations of the Klondike and the higher Canadian Haines Highways to possible see snow or snow rain mix for the weekend period.

AVIATION

Onshore flow with showers remains the main aviation concern today. Overall ceilings and vis have been hovering around 3000 to 4000 ft across the panhandle with some heavier showers briefly dropping ceilings to as low as 1500 ft and vis to 5 miles at times. Showers are expected to continue into tonight with a gradual decreasing trend overall from South to north into Wednesday. MVFR ceilings may become more widespread late tonight and early tomorrow before coming back up to VFR mid to late morning Wednesday. Some isolated lightning is also being observed this afternoon, mainly along the outer coast between Cross Sound and Yakutat. That may persist into tonight before diminishing.

Surface winds are still gusty at times currently, but are reduced in speed from yesterday. Highest gusts are likely near the heavier showers. Skagway/N Lynn has been gusting to around 30 kt at times today as well. May still be some light turbulence in some areas this evening from that. Winds are expected to remain somewhat gusty through this evening then start to diminish overnight.

MARINE

Outside: As of Tuesday afternoon, blustery onshore flow continues as a low weakens over Prince William. ASCAT passes highlight winds of moderate to fresh breezes out of the WSW. Altimeter wave heights indicate seas of 10 to 15 ft; highest seas in the central Gulf. Winds continue to weaken across the Gulf, allowing wind seas to begin to diminish and underlying WSW swell to flourish. Thinking we maintain WSW 9 to 12 seconds near 10 ft along the majority of our coast.

Overall, Wednesday should be much better conditions across the Gulf with winds at or below moderate breezes and swell diminishing. Light winds and lower sea state persist into Thursday afternoon, as a low develops and moves into the British Columbia coast while a surface high shifts into the Gulf. For us humble folks in Southeast Alaska, expecting a tight north to south pressure gradient to develop, driving northerly winds across the coast, inner channels, and into Dixon Entrance. Main impact for the eastern Gulf will be along coastal waters as northwest winds build to fresh to strong breezes, driving stair master fresh seas of 10 to 13 ft, focused from Cape Edgecumbe to Dixon Entrance, highest northwest seas impacting western Dixon.

By Thursday, underneath the northwest fresh seas will be westerly ground swell from Typhoon Choi Wan, followed shortly by additional westerly ground swell from an extra-tropical transitioning Choi Wan, likely about 1 ft near 17 to 19 seconds.

Inside: Certainly, a breezy few days across the inside; however, winds should be on their way down Wednesday afternoon as the supporting low in the northwest Gulf dies out, leaving behind a weak surface pressure gradient. Expecting much better conditions Thursday morning with light winds, some fog in the mornings, and lighter rain. Thursday afternoon into Friday northerly winds build across the inner channels, particularly impacting north-south orientated channels like Lynn, Stephens, Chatham, and Clarence. At this time northerly winds should hold near moderate to fresh breezes, with Lynn Canal likely picking up a few hours of near-gale force conditions Friday. Forecast was based on surface pressure gradient between Whitehorse/Juneau and Skagway/Juneau, with a stable but warmish boundary layer profile to the north of the coast range, limiting wind potential. No freezing spray concerns as water temperatures are still above 45F, with air temperatures above freezing.

AJK WATCHES/WARNINGS/ADVISORIES

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