textproduct: Juneau

UPDATE

Update to the Aviation Section to include the 18z TAFs.

PREV DISCUSSION......ISSUED AT 532 AM AKST Sun Jan 18

SYNOPSIS...

Key Messages:

- Decent break in weather for much of the region into the start of next week.

- Main threat to mariners and aviators is periods of dense fog, most likely in the morning and evening hours.

SHORT TERM.../Through Sunday night/ Rather quiet weather across the panhandle this morning with mostly high thin clouds overhead and lighter winds. As a result fog has become a prominent feature in the inner channels this morning with visibility dropping below a half mile at times in some areas. Dense fog advisories remain up for many of the central and northern inner channels until 10 am.

Not much change expected over the next 24 hours with lighter winds and mostly higher level clouds persisting. Fog will be the main concern overall. Expect the current fog to diminish later in the morning. However, since we are still within a month of the winter solstice, the sun angle is still rather low so fog may stick around in some areas through the day (though may not lower visibility as much). With the continued low winds and little cloud cover expect the fog to return/persist Sunday night for many inner channel areas.

LONG TERM...Continued little change for the long term, with quiet weather and above normal temperatures dropping to below normal temperatures by the end of the week. A strengthening mid/upper level ridge stretching from the Interior of the state down through SE AK will divert would-be weather makers well away from the panhandle. As the ridge retrogrades into an omega block like feature to the west, building high pressure in the Yukon will increase northerly winds. Warm 850 mb temperatures, which is helping hold this ridge in place, look to be slowly eroded away by the cooling temperatures in the Yukon area pushing southward. Currently expecting to see by the end of this upcoming week a return to highs in the mid 20s to low 30s for most areas.

AVIATION...Dense fog conditions continue this morning across the Inner Channels but FAA webcams are starting to show some improvements for certain locations like Wrangell while the fog remains very much entrenched elsewhere. High level clouds continue to move across the area but clearing over the Gulf has allowed for some places to frost out like Yakutat. There is still some uncertainty that the fog breaks today across the Inner Channels and will remain going into tonight and tomorrow. Another concern will be if the fog redevelops this evening due to an unchanged airmass. If this fog remains in place or redevelops, LIFR conditions will continue to be a problem. Otherwise VFR conditions will be the predominant weather.

MARINE... Inside (Inner Channels): Low winds and banks of fog are the main forecast for the inner channels into early next week. Winds in most areas remain less then 15 kt and mostly northerly or easterly with those conditions expected to last into early next week. Fog has developed in many areas overnight with visibility down below 1 mile at times. The fog is expected to diminish later this morning before returning again Sunday night, though some could stick around through the day Sunday due to low sun angle at this time of year. Seas are mostly 2 ft or less through higher seas up to 7 ft will be found near ocean entrances with a southerly exposure through this evening as S swell in the gulf gradually diminishes.

Later, around mid week, weak outflow will begin. This will mainly affect the northern inner channels with Lynn Canal likely experiencing northerly winds increasing to fresh to strong breezes (17 to 27 kts) due to a strengthening pressure gradient. We will continue to monitor and update the forecast as these slightly stronger winds get closer.

Outside (Gulf and Coastal Waters):Largely quiet weather over the gulf as well. Highest winds are Southeasterly winds of 15 kt from the central gulf up to Cape Suckling this morning. Those winds should gradually diminish through today with lighter winds expected through the first half of the week. Seas have shown a subsiding trend through the last 24 hours currently sitting at around 7 ft mainly due to S swell with a period of around 12 sec. Seas are expected to continue the subsiding trend down to 5 to 6 ft by tonight with those conditions persisting into next week though the swell direction will change from a south direction to a more W to SW direction by Monday.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Dense Fog Advisory until 10 AM AKST this morning for AKZ320-321- 324>327-329. MARINE...Small Craft Advisory for PKZ652-671-672.