textproduct: Juneau

SYNOPSIS

Key Messages:

- Onshore flow will keep mainly cloudy skies and rain showers for the northern panhandle, while high pressure ridge will bring partial clearing and drier conditions for the southern panhandle.

- A stronger system and weak atmospheric river will bring gusty winds, elevated seas, and moderate to heavy rainfall for the weekend.

LONG TERM.../Monday through Wednesday/

As the low slowly dissipates near south-central AK, it will meander and track multiple fronts across the panhandle. This setup, reinforced by a consistent slew of upper level troughs and divergent flow aloft, keeps precipitation in the forecast for the extended period, although overall impacts are expected to diminish gradually through the week. One thing of note is as the low dissipates, the pressure gradient over the northern panhandle becomes more north to south oriented, causing a potential increase in winds within Lynn Canal through Monday and Tuesday.

AVIATION.../Through 00z Sunday/

The remnants of a previous system continue to bring occasional dips to MVFR for some of the panhandle this afternoon, with some areas in the far southern panhandle seeing some breaks in the clouds. Other than drops from scattered showers, generally VFR conditions prevail through Friday afternoon with CIGs around 3000 to 5000 ft. These conditions are expected to persist through the next few hours, with the next system heading toward the panhandle already beginning to send high, thin cirrus over parts of the southern and central panhandle ahead of the front. The potential for showers will increase through the next few hours as the front approaches, though the main band of rainfall is still expected to reach PASI around 6Z and move into the coast through 6-10Z. The band will continue to push into the northern and parts of the central panhandle through 8-12z, bringing light rain and winds up to 10 kts through the early morning hours of Saturday. The system is expected to bring periods of MVFR CIGs and potential for lowered VIS with heavier rainfall, mainly along the outer coast and through the Icy Strait Corridor. Conditions are anticipated to be slightly more favorable than they looked this morning, with the interior potentially holding on to VFR conditions for longer if the front begins to fall apart during its push across the panhandle. The southern panhandle may avoid all of this first front, with only a slight chance for PAKW to see any rain through the period.

Behind the front, a brief break may be possible before the next moisture-heavy front moves in. This stronger front is anticipated to reach PAYA by the very end of the period and push inland Saturday. This front will bring widespread gusty winds and heavy rainfall through the weekend, bringing conditions down to at least MVFR to IFR across the panhandle.

MARINE

Outside: Current SITREP Friday morning across the coast is light winds, with seas an impressively low 4 to 5 ft along our coast. A short break. Upstream in the western Gulf a developing gale force low is rapidly shifting northeast, which will serve as the source for elevated winds/seas over the weekend. Expect easterly near gale force along Cape St. Elias by 2am to 4 am Saturday, with southeasterly strong breezes along the Chichagof/Baranof coast. Winds continue to quickly build Saturday morning, with sustained winds of strong gales, gusts to storm force, along Cape St. Elias and gale force near the Fairweather Grounds. Winds build to strong gales for much of the coast of the Alexander Archipelago Saturday night, with winds shifting to the south and slowly coming down through the day Sunday.

Touching on seas, our gentle sea state diminishes overnight Friday along the northern coast. Current forecast suggests fresh seas near 17 ft by 12 to 3 pm Saturday, potential reaching near 19 ft overnight Saturday into Sunday morning. For the remainder of the coast, expecting 15 ft seas to be the theme, with an area of 20 ft seas possible near the Fairweather Grounds to coastal waters south of Yakutat. Multiple wave systems will be present; large and confused seas. As we move into Sunday primary wave direction will begin to shift from the south, becoming southwest Monday night.

Inside: The northern inner channels continue to be a tricky forecast, with winds ramping up to near-gale force Friday morning in Lynn Canal. Thinking these winds are caused by a disturbance moving along the Yukon border helping to tighten up the pressure gradient. 20 to 30 knot winds should diminish to 15 to 20 knots Friday night for the north, including Point Couverden, northern Stephens, and Lynn Canal.

Moving past the northern challenge, primary focus for the inner channels is a front moving across the inside Saturday evening into Sunday. Primary theme will be strong breezes, with near gale to gale force for a few hours likely as the front moves over. At first, winds will flow up from Clarence Strait out of the southeast with easterly winds out of Icy Strait and Cross Sound. As the front moves over these southeast winds will become southerly, beginning to increase as they flow up Lynn Canal and Glacier Bay late Saturday night into early Sunday morning.

Moving into next week southerly fresh to strong breezes continue to impact the inside.

HYDROLOGY

A stronger system is expected to move into the panhandle Saturday into Sunday, bringing periods of moderate to heavy rain. During the peak of heavier rainfall during the overnight hours, rain rates could exceed 0.15 inches per hour. Moderate to heavy rates are expected to continue for any given location for a period of around 12-18 hours before decreasing. Total rainfall accumulations for the event are expected between 1.5 - 3.0 inches, with greatest amounts in the central panhandle. Upwards of 5 inches will be possible for higher elevations. Due to the short nature of the heavier rainfall, smaller creeks and streams will rise quickly, but are not expected to flood.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory until 4 PM AKDT this afternoon for AKZ318. MARINE...Gale Warning for PKZ652-662>664-671-672. Small Craft Advisory for PKZ053-641>644-651-661.