textproduct: Juneau

SYNOPSIS

Key Messages:

- Rain showers are fewer and farther between this morning, but will be increasing in intensity and frequency by this evening.

- Winds fairly benign across inner channels this morning before increasing with next front approaching this afternoon and evening.

- 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

Scattered showers continue to move across the panhandle with larger breaks between showers this morning, keeping most areas at VFR to MVFR conditions. Some heavier showers will continue to drop VIS down to 2-4SM at times through the morning, but these will quickly move through and be followed by a break with a return to MVFR/VFR conditions after the shower passes. Some areas around PoW have begun to see clearing overnight, bringing 1-2SM VIS as patches of fog have developed, however much of this fog remains shallow and not particularly widespread, expecting to lift into the morning.

A more organized wave of precipitation is expected to move across the northern and central panhandle this afternoon starting with the NE outer coastline at 18-20z. This will keep most areas at MVFR and bring some elevated winds across the area, with CIGs down to 1500-2500 ft expected through the end of the TAF period. Winds will increase to 10 kt with some gusts to 20 kt as this pushes through. PAGY and PAHN will see the strongest of these winds, picking up by around 21z and increasing through the evening to 15-20 kt with gusts to 25-30 kt.

While most locations from PASI to PAPG and northward will see deteriorating conditions again through the afternoon, the southern panhandle will begin to see improvement between 21z and 03z to VFR conditions.

MARINE

Inner Channels: S to E winds of 15 kt or less dominate the inner channels this morning and seas are mostly 3 ft or less. That will be changing into this afternoon and evening as an upper trough moves through the area. Lynn Canal will see the higher winds with 25 kt S winds expected. The northern part of the Canal could see slightly higher winds up to 30 kt at times overnight as well. Other areas of the inner channels from Sumner Strait northward will see 15 to 20 kt winds overnight Wed night. Seas will be on the order of 4 to 5 ft. Seas near ocean entrances exposed to the W and SW will likely be a few feet higher due to persistent W swell from the gulf through Wed night. Winds and seas are expected to diminish to 15 kt or less into Thursday and will stay mostly low into Friday. The exception might be N Lynn where 20 kt S winds might persist into Friday.

Gulf Waters: S to SW flow around 15 to 20 kt is the main rule of the day across the gulf waters. That will not change all that much into the late week except for a diminishing trend in wind speeds into Thursday after an upper trough moves through. Seas are around 6 to 8 ft with a persistent W swell around 5 to 7 ft (period around 10 sec). These seas will persist until Thursday when a subsiding swell and lowering winds lead to a diminishing trend in waveheights down to 4 to 5 ft by Thursday night.

AJK WATCHES/WARNINGS/ADVISORIES

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