textproduct: Juneau

UPDATE

Aviation update, and Long term forecast updated.

AVIATION

After 06z issuance. Remains of the front pushing through the southern panhandle with a band of wind that is causing some local wind shear and turbulence issues. Showers following into the area. Most of those spinning in from the gulf northern of the Sitka area this evening, and Yakutat seems to be in the prime location to receive the showers and most them are reporting to be moderate to heavy showers and Visibility in these showers are 2 to 3 miles leading to IFR condition for the NE gulf coast.

Expect to see showers spread further to the southern coastal areas headed into Monday. A surface low of the NW gulf will be shifting east with will bring a larger cluster of showers into the Northeast gulf to Monday as well.

PREV DISCUSSION...ISSUED AT 427 pm Sun Sep 27

SYNOPSIS...

Key Messages:

- Rain continues this evening into tomorrow with the heaviest rainfall expected through this evening across the southern panhandle. Total accumulations of 1-3 inches in 24 hours possible.

- Winds likely to remain gusty at times through early next week with multiple weather systems.

- Temperatures mainly seasonable with highs averaging in the 50s.

SHORT TERM...Gusty winds and moderate to heavy rain continue to impact the panhandle Sunday afternoon, primarily from Icy Strait southward to Dixon Entrance. The first round of gusty winds was associated with the initial frontal passage earlier this morning from broad troughing over the Gulf of Alaska. This afternoon, a short wave feature spinning up in the wake of this initial frontal passage is bringing enhanced winds once more and also is responsible for the fresh influx of moisture to the central and southern panhandle this afternoon and through this evening. Wind advisories remain in effect for portions of the southern panhandle through this evening, while breezy winds with isolated gusts up to 35 mph remain possible around Juneau through the afternoon hours. Another pocket of cooler air aloft from this shortwave feature is expected to bring some instability to the southeastern gulf through this evening. This predicated the inclusion of isolated thunderstorm potential, with the highest chances being along the outer coast of Prince of Wales Island.

After this shortwave feature moves through, onshore flow will continue into early next week as an area of low pressure gradually drops southeast into the central gulf from the vicinity of Cook Inlet. This low pressure will stagnate over the north central gulf, but continue to bring onshore flow and generally unsettled weather through midweek. Even as this one feature continues to weaken, another is expected to take its place forming in a similar area near Cook Inlet. Overall a continuing active fall pattern for the week ahead with seasonable temperatures in the low to mid 50s, and cloud cover generally limiting cooling overnight.

LONG TERM.../Wednesday tp Sunday/...Active weather continues in a typical Southeast Alaska fall fashion through the extended forecast. A weakening low anchored in the gulf dissipates as it drifts north and melts into the central gulf coast by Wednesday morning. General upper-level, onshore flow mid week will leave the panhandle experiencing showery activity, with higher potential for breaks in the clouds. However, conditions are expected to deteriorate Wednesday night into Thursday as another front approaches. Another low moving NE out of the Pacific looks to move over the Haida Gwaii or BC coast region Thursday; rain may cover the southern panhandle, but another feature will drop into the northern gulf and track east over the northern panhandle into Friday. Continuous rain and gusty winds across the region could last into the weekend as additional waves of moisture track across the Gulf of Alaska. There looks to be a stronger low moving into the western gulf with an associated frontal band arcing to the central gulf by Saturday, bringing 20 to 30 kt winds approaching the gulf coastal zones Saturday to Saturday night. Expect winds to pick up along the coast and through major marine waterways, with Small Craft Advisory conditions likely starting late Wednesday night. Additionally, low cloud ceilings and steady rainfall will reduce visibility, creating mountain obscuration and potential delays for regional aviation throughout late week and the weekend. Overall, the end of the week's forecast will stay on the wet side with fairly continuous rain, with higher amounts associated with the frontal bands and lows.

AVIATION... For 00z issuance...

An upper level disturbance following a front this morning is keeping winds gusty, and creating an environment for LLWS, especially at southern panhandle locales. Relative to our current situation, the atmosphere will become a bit drier this evening/tonight, providing for some lifting and breaks in clouds. As a low from the Bering Sea progresses east across the Gulf, its impacts will be visible in another setup for overcast skies which will sit between 2-5kft. Unfortunately, this means over then next 24 hours many TAF sites will move between VFR/MVFR on a short scale that is tough to depict in a TAF.

Wind gusts and shear will die down this evening and into tonight as the influence of the front and aforementioned disturbance wane. Expect rain to continue as the new low moves in, but vsby issues should be rare to non existent on Monday as rain rates will be lighter than Sunday, and fog is not expected with such a thick cloud deck and precipitation.

MARINE... Inner Channel: The back end of a strong frontal system is moving across the panhandle this evening, bringing strong winds and gusty conditions. Winds across the northern inner channels have already begun to diminish, with the southern panhandle to be the main concern through the rest of Sunday night. Strong breezes with gale force gusts can be expected from Stephens Passage, Fredrick Sound, and southern Chatham southward, with Clarence Strait expected to hold elevated winds through early Monday morning. After this system moves through, winds will be largely pressure gradient driven with mainly N/S oriented channels seeing moderate to fresh breezes through the beginning of the week. The biggest point of uncertainty is how high the winds will be in northern Lynn Canal through Monday due the apparent orientation of the pressure gradient. Winds are expected to reach about 20kts, but there is a chance that they could fall below this.

Outer waters: Winds across northern coastal waters have begun to diminish to moderate breezes while southern coastal waters will likely to see strong breezes with gale force gusts through Sunday night. Winds are only expected to decrease from here as the center of the low pressure system moves southeast across the gulf. Significant wave heights range from 8ft in the northern gulf to 14ft in the southern gulf and should return to 4-6ft by Tuesday night.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory until 1 AM AKDT Monday for AKZ330-332. MARINE...Small Craft Advisory for PKZ022-031-033>036-053-641>644-651-652- 661>664-671-672.