textproduct: Juneau

UPDATE

Updated Aviation section for 18z issuance.

SYNOPSIS

Key Messages:

- A brief lull in heavier rain showers is expected Sunday before a stronger low moves into the Gulf, bringing another round of precipitation through Monday.

- Potential for another lull in the weather starting mid week as high pressure tries to move into the area.

LONG TERM

Largely uneventful long term in terms of impact, but several interesting features and tidbits. The first being Tuesday morning, as the stronger low moves down from the NE gulf coast towards Dixon Entrance. Rather strong surge of cold air looks to be associated with this low; and with some leeside troughing from northwesterly winds, it could be as low as 990 mb near Yakutat with 850 mb temperatures dropping below 0 C. As a result, expecting lapse rates around the low center to be stronger. With strong vorticity advection, expecting plenty of lift with the possibility of thunderstorms in the outer coast. Most of the rain accumulations look to be on the outer coast with persistent onshore flow, but since this low looks relatively transient, not expecting any one area to have extended periods of moderate to possibly heavy rainfall.

As it moves towards the southern panhandle, another shortwave trough looks to come across the gulf waters, merging with the existing low near the panhandle, strengthening it again. There is some uncertainty on exactly how this shortwave will merge with the ongoing system, but definitely trending towards impacting the Canadian areas.

Going into the mid to late week, high amplitude ridging returns with northwesterly flow, drier conditions, and warmer temperatures.

AVIATION

Unfortunately, not expecting any large scale improvements for most of the inner channels today, only marginal improvements. In wake of the front last night, lingering low clouds, lighter winds, and lower visibilities down to IFR with spotty LIFR will slightly improve to MVFR conditions. On the coast, Sitka and areas north along the coast look to break out into VFR conditions, primarily from the stronger northwesterly flow aloft. Western Prince of Wales Island does not look to be that lucky, with mainly MVFR and onshore flow.

Expecting to see a return to low MVFR and IFR tonight, as multiple shortwaves both in the northern panhandle and southern panhandle move in. Guidance looks somewhat heavy handed in IFR to LIFR, but due to rain rates not looking as strong as this previous front, combined with wind mixing, not expecting as bad as conditions as last night.

Not expecting any LLWS criteria from these systems moving through tonight, but may have gusty winds associated with TAF sites from Icy Strait southward.

MARINE

Outer Waters: Somewhat active gulf of Alaska over the next few days. At least two lows will be moving SE through the eastern gulf from the Prince William Sound area. Overall the wind pattern over the gulf favors W to NW winds over the offshore marine zones, while the winds directions will be more variable near the coast switching from S and SW ahead of each low, becoming more easterly as the low passes, and finally becoming more N and NW in the wake of the lows. Highest winds will be with the second low that will be moving through Monday into Tuesday with near gale expected for the central gulf waters. Near coastal waters will feature weaker winds of around 20 kt or so even with the second stronger low. Seas will be going up and down as well with up to 8 ft seas for the current system and up to 13 ft seas out in the central gulf for the second system. In between systems on Sunday, seas will be as low as 6 ft. predominate swell will be around 3 to 5 ft out of the W for most of the next few days.

Inner Channels: The front that is moving through right now is not as strong as the one Saturday and winds are expected to gradually diminish into Sunday. Likewise seas are around 4 ft or so for most areas and will gradually subside as the winds do. Of greater concern has been the reductions in visibility due to rain and fog. Some areas have been as low as 1 mile and more areas that low will likely be encountered through the evening and overnight before improving Sunday. There is another period of higher winds and seas expected for Monday as a new front moves in at that time. Wide spread southerly winds of 20 kt expected across the northern 2/3rd of the inner channels starting late Sunday night and continuing through Monday night before diminishing. Highest winds will be in Lynn Canal where 30 kt winds could be observed Monday morning.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-022-033-036-641>644-651-661>664- 671-672.