textproduct: Juneau

SYNOPSIS

Key Messages:

- To end the work week, another strong low will move up from the south late Thursday night into Friday, primarily impacting the southern panhandle with wind gusts greater than 40 mph, gale force winds in the marine areas, and additional aviation wind concerns.

- Warm and wet weather continues into next week with the potential for a strong system mid next week.

LONG TERM

Mid and extended range forecast has the panhandle mainly locked into a warm wet pattern well into next week. The main driver of this is the upper level pattern which features a broad trough over mainland Alaska, Bering Sea, and the northern Pacific while an upper ridge is parked over the US west coast and western Canada. This leaves much of the gulf of Alaska and the Panhandle under S to SW flow aloft with the pacific storm track directed at the Gulf for much of the period.

Lower in the atmosphere, the dominate S to SW flow will bring in a series of lows and fronts this weekend and into next week with the strongest of which expected sometime mid next week. The first of which in the mid range will be moving in from the south Saturday evening, followed by another wave Sunday night. Both of which will bring more rain and some wind mainly to the southern panhandle through early next week, but neither is expected to be outside the norm for rain (around an inch for each front or wave) or wind (gusts to 40 mph/min to mid gale force) for this time of year. The mid week system is another story. That system has the markings for another atmospheric river with the potential for up to 1 to 4 inches of rain for many areas, but it will mainly be focused on the southern panhandle. This system also looks like it will be a wind maker as well with widespread gale force winds for the gulf waters expected while the inner channels could see winds of 25 to 35 kt. The timing of this system is still uncertain with most effects starting as early as Monday evening or as late as early Tuesday morning and lasting into Tuesday night. Guidance is also indicating a rather strong followup system on Wednesday, but certainty on that is even worse with wildly different possibilities for track and strength on that feature.

In addition while most low elevation areas of the panhandle will be warm enough for rain, the higher elevations of the Klondike Highway will still be cold enough for snow. Snow levels will be hovering around 1500 to 3000 ft along the Klondike into next week. While there is not much potential for significant snow through the weekend since most of the precip will be south of that area, the more substantial system mid next week could bring more substantial precip (and more substantial snow) to the Klondike Highway and will continue to be watched.

AVIATION

For the 00Z forecast package, we note a break in IFR initially with a break in the rain, then we trend back towards IFR/MVFR late tonight into Friday as the next frontal boundary works in from the south and widespread rains and lower ceilings move across SE Alaska. Main timing for lower conditions from Sitka southward will be through 06Z tonight, and for areas to the north toward 18Z Friday. LLWS will continue near Ketchikan through the night ahead of the approaching frontal boundary before diminishing after 18Z Friday, and north around Yakutat (in association with the strong low over the north central GULFAK) through mid evening before diminishing overnight.

MARINE

Marines: Outside (Gulf and coastal waters):Thursday a storm force low with minimum pressure near 967mb will continue to move NW, making landfall over the Kenai/Cook Inlet over the next 24 hours. Winds continue to slacken across our coastal waters, with the main threat focused around stout southwesterly swell moving in. Satellite derived wave winds and altimeter wave heights highlight 20 to 24 ft wave heights in the central gulf, which will continue to travel north through the afternoon. While wave heights diminish as they spread north, long period energy will impact major ocean entrances like Yakutat Bay, Cross Sound, Chatham, and Sumner. Caution is advised, especially during ebb tide cycles. Early Friday a rapidly moving low will slide into the southern Panhandle, with confidence increasing on track and landfall of this feature. Expect a quick hit of near-gale to gale force southerly winds in Clarence Strait, with near-gales to strong breezes impacting western Prince of Wales. Winds and seas relax Saturday before a large system moves into the gulf, driving gale force southerly easterly winds.

For mariners transiting the northern coast from Cross Sound to Cape St. Elias, expecting significant wave heights to fall below 10 ft by Friday afternoon and remaining below 10 ft until early Sunday.

Inside (Inner Channels): Thursday winds continue to trend downward, with web camera images and observations from the Marine Exchange of Alaska highlighting moderate to fresh breezes (or less) for the majority of the inner channels. Main problem area early Thursday was south of Gravina Island, with SAR satellite derived winds showing gale force conditions into Dixon. Winds will be light Thursday afternoon into the evening but dont get complacent, they will increase from the east to north as a fast- moving low pushes toward the southern Panhandle from Haida Gwaii. Expecting near gale to gale force conditions to impact Dixon and southern clarence sometime near midnight, with winds becoming southerly Friday morning. This southerly surge will move north through the day, bringing strong breezes to near gales into Stephens. One exception of winds tonight will be Lynn Canal and Taku, where a tightening pressure gradient will help drive a few hours of strong breezes to possibly near gales out of the north, with a southerly surge of fresh breezes Friday night.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory from 4 AM to 3 PM AKST Friday for AKZ328-330-332. MARINE...Gale Warning for PKZ651-652-671-672. Small Craft Advisory for PKZ012-013-022-031-033>036-053-641>644- 661>664.