textproduct: Juneau

UPDATE

Conditions have improved with the fog in the central panhandle area, so have cancelled the Dense Fog Advisories.

SYNOPSIS

Key Messages:

- -Quieter weather for the first part of the work week with light rain showers possible and potential for overnight fog.

- A fast moving low moving just south of the panhandle will bring a period of moderate rainfall Tuesday for the southern panhandle.

- A larger, impactful system to move into the Gulf midweek and impact SEAK by late week, bringing moderate to heavy rain and elevated winds.

LONG TERM

Weather for the long term continues to look unsettled as forecast guidance continues to show multiple lows moving into the panhandle for the end of the week and into the weekend. Forecast guidance still shows some uncertainty with the exact location and strength of the low moving in for Thursday. This low will track around the parent low which looks to remain near Kodiak Island. While the parent low remains in the Western Gulf, some forecast guidance is pointing towards a low forming on the triple point convergence for Friday which could bring another shot of moisture and winds to the panhandle.

Attention then turns towards the weekend as deterministic and ensemble forecast guidance have the remnants of Typhoon Koguma moving into the Gulf and interacting with the low that has been lingering in the area. Right now, guidance is split on whether this system that develops moves north into the southern panhandle or dives south. Right now, Euro/EPS guidance wants to bring the low north along Haida Gwaii Sunday evening into Monday morning before moving into the Southern Panhandle. The GFS/GEFS wants to bring the strengthening low up to Haida Gwaii before diving south in British Columbia and the PNW. Canadian/GEPS is leaning more towards the Euro solution but not as strong and does not move the low as far north. Due to the uncertainty of this track, a lot of uncertainty remains regarding the weather for the weekend and start of next week.

AVIATION

/ through Tuesday night / Lower level clouds along areas of fog over the south central panhandle with a region of Dense fog in the Petersburg region and possibly over to Angoon this morning with Ketchikan and Wrangell also reporting morning ceilings below 1000 ft. A pocket of showers will also move northeast and over the British Columbia coast may spread some rain to the southern panhandle tonight.

A couple bands of showers are moving over the northern Gulf of Alaska and then onshore over the NE Gulf coast. THe last organized band before the next system will mover over the gulf and into the coastline Tuesday night. Smaller isolated shower cells do continue behind the last trough.

A bigger low/system is about 500 nm south of Cold Bay and this low will be winding up an approaching the Alaska Peninsula SW of Kodiak Island Wednesday evening, with much of he energy Tuesday and Tuesday night in the gulf going Northward the main event will west of the region. Anticipate the front for this system to impact the panhandle Thursday. Showers for the Northeast Gulf coast and northern portion of the panhandle today and tonight with best chance of them overnight. Isolated thunderstorms with some of the cells are possible mainly near coastline where additional lift will help the storm development.

For other hazards the locally breezy conditions around Lynn Canal to result in light turbulence.

MARINE

Outer Waters: Southwesterly gentle to moderate breezes persist until midday when a weak low moves north toward Prince William Sound, causing a easterly barrier jet to form with sustained winds around 25 knots between Cape Suckling and Icy Bay. Southwesterly seas will remain at or below 8 ft through Wednesday morning. By Wednesday afternoon, east to southeast winds build in the eastern Gulf, reaching near gale force over much of the coast by early Wednesday evening and seas building to 10 to 12 ft. Thursday morning conditions continue to deteriorate as a front moves into the coast, with gales to strong gales impacting many areas and seas reaching 20 to 25 ft in the northern Gulf, seas reaching 15 ft across the outer coastal zones. Southwesterly winds of fresh to strong breezes persist Friday with thunderstorms possible along much of the coast.

Inside Waters: Light and variable winds observed across a majority of the region this morning, allowing for fog development within central inner channels, except for in North Lynn Canal which came up again overnight to around 20 kts and will likely remain elevated before gradually decreasing to 10 kts by this evening. A quick moving low pressure system tracks north today, amplifying winds and seas in Clarence Strait. A stronger system is on the horizon, arriving late Wednesday night into Thursday. Winds strengthen across much of the inner channels to 20 to 30 knots, with localized areas of gales possible near ocean entrances. This system will particularly impact east to west oriented channels as the pressure gradient strengthens. There is a slight chance for thunderstorms to impact the southern panhandle Friday, causing erratic gusty winds.

HYDROLOGY

As of early Tuesday morning, the fine tuning the arrival and location impressive plume of moisture looks to be associated with the incoming atmospheric river Thursday morning continues to fairly solid. Strong WWA ahead of the moisture looks to raise freezing levels to above 5000 ft, with an atmosphere relatively saturated. Associated PWAT via ensemble mean looks to exceed the 95th percentile for this time of year for the southern panhandle. This coupled with the strong flow aloft means that IVT will likely exceed 500 kg/ms at around 80%. The big question here is timing of this moisture, and if any mesoscale features will keep this flow of moisture directed at the southern panhandle for longer. Dynamics continue to favor higher rain rates, with divergence aloft and stronger 850-700 mb southerly flow. Rain rates could exceed 0.3 in/hr for longer periods of time, and exceed 0.5 in/hr at elevation. Flooding is certainly possible with this rainfall intensity, but uncertainty in duration (see long term) has cast some doubt on overall impact level. Stay tuned for updates as the event approaches.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Gale Warning for PKZ036-641-642-644-652-661>664-671-672. Small Craft Advisory for PKZ021-022-033>035-053-643-651.