textproduct: Juneau

UPDATE

Update to aviation section to include 6z TAF issuance...

SYNOPSIS

Key Messages:

- Numerous snow showers ongoing across the southern panhandle. Winter Weather Advisories remain in effect through Sunday morning across the central and southern panhandle. Decreasing showers into Tuesday.

- Outflow northerly winds will start to increase Tuesday for the northern channels and NE gulf coast.

LONG TERM.../Tuesday through Thursday/

Confidence continues to increase on the potential for the northern panhandle to see a drier trend midweek, with much of the precipitation remaining for the southern panhandle. This next system will move into the northern Pacific Tuesday, weakening quickly while it approaches the southern panhandle Tuesday into Wednesday. The model guidance today is keeping with the low moving into the coast of BC, between Vancouver Island and Haida Gwaii. This system will follow behind the low moving along the coastline Monday as it moves away from the panhandle as it weakens by Tuesday morning, giving the panhandle a break from the precipitation during the day before the next system moves in from the south. Precipitation will return to the southern panhandle by Tuesday night as this next low moves north near Haida Gwaii. While most of the precipitation impacts will be out of our area due to the low tracking to the south of the panhandle, the front will still bring some precipitation to the furthest southeast part of the panhandle. Another weaker low will develop off the southern coastline by Wednesday morning, pushing some precipitation further into the panhandle but largely remaining south of Icy Strait. This low looks to linger in the Gulf, and though model guidance is showing multiple different positions and strengths of the low, the solutions largely agree on the low remaining in the south- central to southeast Gulf. This will continue the pattern of precipitation hitting the southern half of the panhandle through Thursday, with the north staying predominantly dry through the week. Some chances of snowfall return for the northern half of the panhandle around Icy Strait Corridor Thursday.

In terms of precipitation, most of the southern panhandle will see snowfall at nights as low temperatures remain in the low 30s and as colder air aloft lingers over the area. During the daytime, much of this will transition to more of a rain snow mix, as temperatures will increase to the high 30s to low 40s throughout the week, alongside snow levels raising to 200 to 400 ft by Thursday. These warmer temperatures along with the low QPF amounts expected will likely not bring as much snow accumulation over the area, particularly into the end of the week as the southern panhandle continues to see some warming. The central panhandle from Sitka to Petersburg and Wrangell may see some cooling with the outflow on Tuesday and Wednesday before the next wave of precipitation moves through, bringing some more potential for longer snowfall into the day and more accumulation from colder and drier conditions over the area.

Outflow winds remain largely unchanged in the forecast, with the main change being an increase to the surface winds for Gastineau Channel and Downtown Juneau with increased confidence in a mountain wave event. Tuesday night into Wednesday morning the area over Juneau will see some 30 to 40 kt cross barrier flow over Gastineau Channel and Taku Inlet, alongside a critical level forming at around 500 mb. The conditions overall look favorable for some 15 to 25 kt winds with gusts up to 45 kt at the peak, though this will be something to watch moving forward as it moves into the shorter term.

AVIATION.../Through 6z Tuesday/

The heavy band of snow continues to slowly spread north through the panhandle, bringing light snow and lowered visibilities to communities along the Icy Strait Corridor and Sitka. There are some dry slots in this band, so Juneau appears to be missing most of this snow and instead is just feeling some of the gustier winds up to 20 kts along the back edge of the band. The rest of the northern panhandle remains clear and relatively calm, with Haines being the only site up north to be seeing some breezy outflow winds starting to pick up between 10 to 15 kts. Behind the band, widespread showers are moving through a majority of the central and southern panhandle, occasionally dropping VIS down to MVFR/IFR conditions, with heavier showers bringing short periods of LIFR conditions to some locations. CIGs aren't as much of an issue in the southern panhandle where most of these showers are still developing as they stream in from the gulf, but locations along the central panhandle are seeing lowered broken CIGs AoB 3000 ft with scattered CIGs as low as 500 ft. In between showers, there will be periods of VFR conditions with good VIS and broken CIGs.

Through the period, there is expected to be another band of more organized showers that pushes through the panhandle in the early morning of Monday, and potentially another one through midday to early afternoon. These bands may bring MVFR conditions and breezier winds as they move through, but areas of heavier showers have potential to drop conditions to periods of IFR/LIFR. These bands may only reach the southern and central panhandle south of the Icy Strait Corridor, while outflow winds in the northern panhandle will start to increase through the channels through the morning and should help to keep those areas more dry and cleared out. Guidance is still not very partial to these outflow winds, but expecting Skagway, Haines, and potentially other communities along the Icy Strait Corridor to see 20 to 25 kts of northerly winds pick up through Monday.

MARINE

Inner Channels: Lower winds across the inner channels today compared to yesterday. Still some 15 to 25 kt winds in Clarence Strait and near Cape Decision this afternoon associated with the low west of POW. We are also starting to see some wind shifts with the northern inner channels starting to show a shift to a N wind as that low moves north. That low is expected to move up Chatham Strait tonight and will stall near Chichagof Island by late tonight. As a result Lynn Canal and Glacier Bay will likely stay a N wind through Monday night at least, while the channels S of Icy Strait will switch back to a south by late tonight. The northern channels will start to see increasing northerly outflow starting Tuesday with possible gale force winds in Lynn Canal and some other northern channels by Tuesday night. Seas will mainly be around 4 to 5 ft or less through Monday night. Increasing seas in the northern channels as outflow starts up Tuesday into Tuesday night.

Gulf Waters: Complex low is still pinwheeling through the gulf this afternoon. The latest shortwave low to affect the eastern half of the gulf is currently just off Prince of Wales Island and moving north into the panhandle. There are some 25 to 30 kt winds near the low center that will move into the Cape Decision area this evening. Otherwise winds are mostly 20 kt or less across the eastern gulf today and will mainly stay that way into Tuesday through there will be varying wind directions as individual low centers move through the area. The waters near the NE gulf coast will start to see some gusty N winds due to outflow from channels and passes along the coast starting Tuesday. Seas are around 7 to 10 ft this afternoon (SW swell of 8 to 10 ft). Expect seas to gradually subside through Monday night due to the low wind conditions and subsiding swell. Seas will start increasing again near the NE gulf coast as outflow winds start to increase Tuesday.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Winter Weather Advisory from 4 AM to 4 PM AKDT Monday for AKZ321- 324. Winter Weather Advisory until 10 AM AKDT Monday for AKZ323. Winter Weather Advisory until 4 AM AKDT Monday for AKZ326>330- 332. MARINE...Small Craft Advisory for PKZ012-013-641>644-651-652-661>664-671- 672.