textproduct: Juneau

UPDATE

For 06z TAF Issuance.

Only changes for TAFS were for slight alteration of fog timing for a few sites. For Juneau, patchy fog has already begun to show up as temperatures dropped slightly faster tonight with the calmer surface winds. Similar to last night this is expected to be fairly shallow and eventually settle as a fresh round of frost on the ground. For Yakutat, a cloud deck around 2000 ft is inhibiting fog development and has a chance to stop it altogether through Sunday morning if no breaks develop.

SYNOPSIS

Key Messages:

- No major weather hazards are expected through Sunday with mainly clear and dry conditions, along with chilly overnight temperatures.

- A weak disturbance will slide south through SEAK Sunday night through Monday, bringing a chance of light rain showers.

- Quiet weather returns for Tuesday with more sun and dry conditions expected.

LONG TERM.../Wednesday through Friday/

Confidence in the long term forecast is fairly high, in that there is great agreement on a large high being situated over the Gulf of Alaska through almost the end of the workweek. This will lead to mostly light winds, with the exception of Wednesday. As a low recedes south of Haida Gwaii further towards British Columbia and a tongue of high pressure comes back south to the Gulf from south- central Alaska, gradient driven winds will be stronger, but weaken over time into Thursday for the upper inner channels, such as Lynn Canal and Stephens Passage.

The next pattern change will come with the end of the work week, as a front moves toward the area later Friday into Saturday as the high breaks down. Guidance has slowed the onset of impacts with this latter system from run-to-run. At this length of forecast, conjecturing at exact impacts is a fool's errand, but elevated winds for most of the panhandle, as well as the next bout of notable rainfall are expected. An early estimate of rain onset would be Friday PM for the northern panhandle

AVIATION.../through Sunday afternoon/

Mainly VFR conditions prevail across the panhandle this Saturday afternoon as high pressure continues to drive the weather pattern, or lack thereof. The exception is Yakutat which has a cloud deck sitting around 2,500ft, moving in off the gulf. Satellite imagery indicates a break in this cloud cover late Saturday afternoon or into the evening before another 2,500ft cloud deck moves in again by the early morning. The TAF forecast is mainly persistence from the previous 24 hour period with the potential for fog to develop at locations such as PAJN, PAGS, and PAPG. However, due to another night of clear skies, temperatures below freezing are expected, which will limit fog formation or cause it to freeze in the early morning hours. Gusty winds in PAGY, PAHN, and PAKT and anticipated to slowly diminish overnight with the rest of the locations experiencing calm winds thorough the period. Sunday is likely to be another clear sky day for much of the panhandle with the possibility of upper level clouds to move across the area overnight and through Sunday.

MARINE

Outside Waters: Persistent ridging in the Gulf of Alaska will bring predominately NW-ly along the outer coast through the weekend. A weak front moves along the NE coast on Sunday causing a shift to lighter and variable winds from Cape Spencer northward. This feature will dissipate by early Monday, though at the same time, with weak troughing in British Columbia and high pressure continuing to build in the western Gulf at the start of the week, the pressure gradient will strengthen, resulting in a slight increase in winds across all outer marine zones with moderate to fresh breezes expected. Seas diminishing tonight, then slowly building to 7-9 ft, mainly over the southern zones through late Monday before trending down once again.

Inside Waters: Winds and seas gradually weaken to 10-15 kts across the inner channels this evening as the pressure gradient slackens with a system moving further south of the region and high pressure in the Gulf becoming the dominant feature. On Sunday, across the northern and central inner channels, expect light and variable winds with a NW component becoming more notable from Sumner Strait southward as winds remain light to gentle breezes.

By the start of next week, winds start to increase again, as low pressure develops south of the panhandle contrasting the high pressure in the Gulf, resulting in an uptick in speeds to 15-20 kts through Tuesday. This pressure gradient looks to favor mainly the N- S oriented channels, noting a potentially more significant increase within Lynn Canal and Clarence Strait.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ661-662.