Marine Weather and Tide Forecast for Sitka and, AK

PREV DISCUSSION
ISSUED AT 436 am Fri Mar 6...

SYNOPSIS...

- Warming temperatures for the end of the work week. A system brings moderate to heavy rain for Friday, wet snow for the Klondike Highway.

- Compact low pressure system to bring widespread gales to gulf waters Saturday.

- Cooler temperatures with rain changing to snow showers over the weekend.

SHORT TERM...An upper level ridge stretching from the eastern pacific into British Columbia and the Yukon will continue to steer energy towards the panhandle through the end of the week and into the weekend. This is also continuing to pull moisture from the central pacific, with ongoing light showers early this morning and moderate to heavy rain on tap Friday as well as snow for upper portions of the Klondike Highway from an approaching gale force front. The source of this gale force front is a developing 970 mb low near Kodiak Island. Winds in the gulf and eventually the inner channels will increase through the morning and into the afternoon hours as the front approaches. For Skagway, wind gusts reaching upwards of 50 mph are expected Friday afternoon and lasting into early Saturday as the front lifts northward. This will bring warmer temperatures with daytime highs reaching the low to mid 40s for a majority of the panhandle Friday at sea level.
Snow levels will also be rising through the day reaching upwards of 7500 ft in the southern panhandle and briefly around 4000 ft along the Icy Strait corridor. Cooler air will then wrap around from the west, with snow levels gradually dropping heading into the weekend.

Many areas that saw accumulating snow during the week will now be facing moderate to locally heavy rainfall on Friday, which could lead to ponding of water in low lying or poor drainage areas clogged with snow and ice. Heaviest precipitation rates are expected to begin late Friday morning and last through the afternoon hours. For more information on another impactful fast moving system Saturday, see the long term discussion below.

LONG TERM...Active weather will continue across SE AK with rain to end the work week, and a transition back to snow by late weekend into the start of next week. On Saturday, a strong low pressure system pushes north east into the gulf bringing sustained strong gale force winds into the gulf with a chance for areas of storm force winds. As this low pushes inland, winds along the gulf coast and southern panhandle, will increase with a 40 to 60% chance for wind gusts near 45 mph and around a 20 to 30% chance for wind gusts reaching 55 mph. These strongest winds are most likely to occur over Prince of Wales Island, Southern Baranof Island, and Annette Island.

A pattern change then occurs late Saturday into Sunday as a low pressure system moves into the far northern gulf. This vertically stacked low will push colder air into the area with continued NW flow. In turn this will decrease snow levels and temperatures across the area returning precipitation back to snow from north to south.
Confidence is higher that precipitation type will become all snow by the end of the weekend. Confidence is lower on how much precipitation and snow the panhandle will see with these colder temperatures.

Along with colder temperatures, as the low moves south, northerly outflow conditions will begin across the north. The transition from southerly to northerly winds will occur Sunday into Monday. Then northerly outflow winds will begin to increase through the start of the week with the potential for gale force winds developing by mid week.

AVIATION...Very active day for flying weather today as a wet and windy front moves into the panhandle this morning. Most areas in the panhandle are already seeing MVFR or IFR ceilings (and occasionally MVFR visibility) this morning and the front has not made it into the panhandle yet as of 4 am (though it is just offshore). Expect visibility and ceilings to show more frequent IFR, but mostly MVFR, conditions as the precipitation moves in later this morning after 14z and it will last into early this evening. It will mainly be rain for sea level locations but snow levels will vary wildly with it being near sea level this morning around Haines and Skagway to nearly 7000 ft across the southern panhandle by this afternoon. Winds will also be on the rise especially for the central and northern panhandle with the highest winds expected this afternoon and evening (gusts to 35 mph at sea level). In addition, higher elevation winds will be somewhat strong resulting in some low level wind shear as well. It will start out as mainly speed shear (35 kt SE winds at 2000 ft asl), but will start to show more directional shear after 2 pm this afternoon as higher elevation winds start to switch to a more SW direction while sea level winds remain more SE or S. Turbulence may also be a problem in some locations today as well. Into Tonight the front will have moved though the area and at least winds will be on the downward trend (except near Skagway) with visibility climbing back to VFR. Ceilings however may still linger around 1500 to 2500 feet in many locations tonight into Saturday morning.

MARINE...
Outside (Gulf and Coastal Waters): The next major system starts to move into the gulf Friday with winds across the northern and Central gulf increasing to gale force by mid day Friday. Seas range from 6 to 9 ft with the highest seas over the south. Primary swell is from the SSW with a height of 4 to 6 ft and period of 9 sec. Seas begin to increase into the 10 to 20 ft range by Friday afternoon due to the increasing winds from the next incoming front. Highest seas expected west of 140W.

Inside (Inner Channels): The inner channels are mostly quiet with 20 kt or less of wind mainly from a S and W direction. Winds start increasing into Friday afternoon as the next front approaches. Shifting of easterly winds to westerly Friday afternoon along Icy Strait and Cross Sound with the frontal passage. Seas largely 5 ft or less through the period except for some higher seas near ocean entrances exposed to the west due to some swell getting into those areas as well as seas reaching up to 8 ft along Lynn Canal due to expected southerly winds reaching gale force Friday afternoon.

AJK WATCHES/WARNINGS/ADVISORIES
PUBLIC...Winter Weather Advisory until 6 PM AKST this evening for AKZ318.
Wind Advisory from 3 PM this afternoon to 3 AM AKST Saturday for AKZ318.
MARINE...Storm Warning for PKZ652-672.
Gale Warning for PKZ012-013-644-651-663-664-671.
Small Craft Advisory for PKZ011-021-022-031>036-053-641>643-661- 662.