textproduct: Juneau

SYNOPSIS

Key Messages:

- An active weather pattern will persist through the weekend as several fronts move over the panhandle.

- 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.

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

Difficult day for aviation concerns. Many areas of the panhandle are observing vis around 3 to 5 miles and ceilings down to 1500 ft or less. A few locations are even down to 1 mile vis (Sitka and Yakutat) and a few hundred feet ceilings (also Sitka and Yakutat). This is due to the second of two fronts that are moving through the area today. This front moved onshore early this afternoon and is just reinforcing the already low conditions that many areas were seeing this morning mainly from Cape Fairweather S and E. The low conditions and rain is expected to last into the evening with rain gradually diminishing afterwards with some improvement in vis. However, ceilings will likely stay low for many areas through the night and will not see significant improvement until Sunday morning and even then will likely stay with MVFR conditions.

Surface winds have been somewhat gusty in some areas, but only gusting to around 25 kt today. With the front moving through this evening these winds will likely not diminish until late this evening. Aloft, winds have not been much higher than what is seen at the surface and pilot reports have only had some isolated areas of light turbulence at low altitudes today (and little to no low level wind shear reports). These wind conditions will likely remain consistent through the evening and will likely improve later tonight as the fronts move out of the area and winds lighten.

MARINE

Inner Channels: Inner channel winds today have not been that strong. Highest winds have been on the backside of Douglas Island (E wind 25 kt most of the day), Northern Lynn, and Clarence Strait (20 kt in both places at various points today) so far. At least for this system, right now is about as high as inner channels winds are going to get. The second front that is moving through right now is not as strong as the first one last night was 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.

Gulf 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.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ661>664-671-672.