textproduct: Juneau

SYNOPSIS

Key Messages:

- Onshore flow continues shower potential until a stronger front and low arrives late Tuesday into Wednesday.

-Another strong system arrives Wednesday night.

-Cooler weather for the end of the week and the weekend.

LONG TERM

An active week continues in the mid-range as a stout jet continues to feed systems into the north Pacific and the Gulf of Alaska. As one system weakens Wednesday as it moves off to the southeast, an additional shortwave trough will reinforce storm development in the north Pacific, allowing a storm force low to develop near 46N 158W. As this system quickly moves into the Gulf of Alaska Wednesday night, southeast winds will freshen up along our coast to gale force and bringing additional moderate to heavy precipitation. For more wind info, see marine section below. Touching on precipitation type, temperatures slowly start trending down through the week, bringing increased chances of snow by Thursday into the weekend for the north. For next week, the primary threat remains focused on outflow across the inner channels, with temperatures dropping into the single digits for the north and teens for the south, helping to prime southeast for future snow.

AVIATION

Generally MVFR ceilings (down to 1000 ft) across much of the panhandle this morning, with some scattered IFR or lower from around Juneau southward in the inner channels. Visibility has not been much of a hindrance though Ketchikan has had some fog develop with vis getting down to 1 1/2 mile at times. For the most part ceilings will be the main concern as most areas remain in MVFR conditions through the day. That starts to change tonight as a new front moves in from the west bringing rain with it. Ceilings will start to lower (possibly as low as IFR) especially in the north, while visibility will mainly stay MVFR at the lowest as the rainfall moves in. Expect conditions to improve again into Wednesday from W to E as the front moves out.

Winds will be the other significant issue mainly later today into Tuesday night. Ground level winds currently are rather light (except Skagway with 20 south winds), but will be increasing this afternoon and evening as the front moves in. Currently there is also some directional low level wind shear over the central panhandle due to winds at 2000 ft coming out of the SW around 20 to 25 kt while surface winds are still E or SE at around 10 to 15 kt. Expect winds to become gusty along the outer coast and in the northern inner channels this afternoon and evening with some areas near Lynn Canal and Juneau gusting to 40 to 50 mph (up to 60 mph at Skagway). Southern panhandle will get in on the gusty winds as well later tonight. Also at this time a lot of the low level wind shear will transition to more speed shear rather then directional as winds aloft and at sea level line up more southerly while speeds increase to around 40 kt at the 2000 ft. Winds are expected to start to diminish Wednesday.

MARINE

Outside (Gulf and coastal waters): A hurricane force low upstream of SE AK, moving into the Bering as of the time of writing, will be responsible for our weather this week, driving a series of secondary gale to storm force lows, gale force south- southeasterly winds, and high wave energy along our coast. The first of these systems will reach the Gulf Tuesday afternoon, bringing near-gale force conditions to our coast. The second system, which appears much stronger, will bring strong gales to waters south of Cape Edgecumbe and seas near 30 ft. There is high uncertainty with where the strongest winds might be, which is resulting in large variance in wave height potential. For now, we highlight south southwest significant wave heights near 30 ft for the Prince of Wales coast and Dixon Entrance, with the potential to see closer to 35 ft by Thursday afternoon.

Inside (Inner channels): Winds have begun to slowly ramp up ahead in advance of the next system. Expect winds to continue to increase out of the southeast Tuesday morning, with near- gale force conditions expected for Lynn Canal and moderate to fresh breezes for major north- south channels. Tuesday night into Wednesday morning, as the low makes landfall, we will see gale force conditions in Clarence Strait and Lynn Canal, with near- gales impacting other major passages. Wednesday afternoon another system approaches, with winds diminishing briefly through the inside before quickly ramping back up to near gale, to gale force, conditions by early Thursday. Winds diminish Friday into Saturday before outflow begins to dominate the region, likely bringing gale force conditions and freezing spray to Lynn Canal and Taku Inlet.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...High Wind Warning from noon today to midnight AKST tonight for AKZ318. Wind Advisory from midnight tonight to 9 AM AKST Wednesday for AKZ318. Winter Weather Advisory from 3 PM this afternoon to Noon Wednesday for AKZ318 Wind Advisory from 9 PM this evening to 7 AM AKST Wednesday for AKZ319. Wind Advisory from 8 PM this evening to 2 AM AKST Wednesday for AKZ323. Wind Advisory from 8 PM this evening to 7 AM AKST Wednesday for AKZ325. Wind Advisory from 10 PM this evening to 5 AM AKST Wednesday for AKZ328. Wind Advisory from 11 PM this evening to 7 AM AKST Wednesday for AKZ330-332. MARINE...Gale Warning for PKZ012-013-031-033-036-651-652. Small Craft Advisory for PKZ011-021-022-032-034-035-053-641>644- 661>664-671-672.