textproduct: Juneau

SYNOPSIS

Key Messages:

- Rain showers likely through the rest of the day Tuesday. Drier at times along the northern gulf coast through Tuesday evening. Another round of showers expected for Wednesday.

- Winds fairly benign across inner channels before increasing with next front approaching Wednesday.

- Temperatures mainly seasonable with highs averaging in the 50s and lows in the mid to low 40s.

LONG TERM.../Friday through Monday/

A low pressure system originating from a mid-level North Pacific trough will move along the Alaska Peninsula and into the Gulf of Alaska this weekend. Reinforced by a stronger system behind it, it will produce prolonged rainfall from Saturday into early next week, fueled by tropical moisture and weak but continuous divergent flow aloft. Models continuing to favor landfall along the north-central coast near Cordova. The system could bring moderate to heavy rain, with the highest totals expected along the northeast Gulf coast and higher terrain, though most of the region will be impacted. Warm advection seems apparent through many levels of the atmosphere along this system, which will allow for a very slight warming in temperatures, but not expecting much of a difference due to persistent cloud coverage across the region this weekend.

Climatological guidance is trending higher, though values remain within seasonal norms. The NE Gulf Coast may see locally heavy, long duration rainfall instead of showery bursts due to limited cold air aloft and minimal convective activity. For the heaviest period (Saturday evening to Sunday evening), 24-hour QPF averages 1.5-3 inches, with up to 4-5 inches at higher elevations. GEFS and Euro ENS indicate PWATs around 175% of normal. The GEPS is trending more aggressive, while the GEFS and Euro ENS align more on timing and intensity. Stronger winds and building seas are also increasingly likely along the outer coast and northern inner channels ahead of the low. The active pattern will persist into next week as the following Bering Sea low reinforces onshore flow, though rain chances should taper off by mid week.

AVIATION

After 06z TAF package Issuance.

Scattered to Isolated showers moving into the panhandle from the eastern part of the gulf. A few of the showers are more enhanced based on satellite imagery. There is some spotty MVFR ceilings of 1500 to 3000 feet, and very localized visibility restrictions.

Conditions should continue through Wednesday with mainly VFR flight conditions anticipated with scattered shower activity.

MARINE

Outside (Gulf and Coastal Waters): The system in the eastern gulf continues to weaken Tuesday, with the low center rotating offshore of the northeastern gulf coast. Westerly fresh to strong breezes (17 to 27 kts) and 8 to 9 ft seas persist through the southeastern gulf Tuesday, with fresh breezes (17 to 21 kts) and 6 to 7 ft seas along the gulf coast of Baranof Island and easterly out of Cross Sound. Winds will weaken overnight as the low diminishes, being replaced by a developing low near Prince William Sound Wednesday morning. This will bring southwesterly moderate to fresh breezes (11 to 21 kts) with 6 to 7 ft seas through the gulf Wednesday. Southwesterly 3 to 4 ft swell at a period of 8 to 10 seconds will decrease to 2 ft at 5 to 7 seconds by Thursday, with gulf winds and seas also decreasing by Thursday.

Inside (Inner Channels): South to southeasterly moderate breezes (11 to 16 kts) and 3 ft seas continue for parts of the southern and central inner channels Tuesday, mainly up through Clarence and Sumner Strait and out of Frederick Sound and Stephens Passage. Other than Young Bay holding on to sustained 20 kt easterly winds, the rest of the northern inner channels are relatively light and variable Tuesday. Winds and seas are expected to decrease Tuesday night before jumping back up through midday Wednesday with another system in the western gulf. This frontal passage will bring 15 to 20 kt southerly winds into the northern and central inner channels, with Lynn Canal expected to be closer to 25 kts through Wednesday evening. Seas will also increase to 4 to 5 ft in areas of the strongest winds. Winds and seas will generally diminish Thursday, though Lynn Canal will stay elevated up to 15 to 20 kts into Friday. The southern panhandle will avoid most of these winds through midweek. Ocean entrances exposed to the SW or W will see higher seas up to 7 ft due to W swell invading from the gulf, but those seas will be gradually diminishing Wednesday as swell subsides.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-641-661-662.