textproduct: Juneau

SYNOPSIS

Key Messages:

- Drier trend expected going into the weekend and into next week.

- Clearing skies and cooling trend to start out the weekend, with overnight temperatures dipping down into the low to mid 30s, and the northern panhandle possibly getting down into the upper 20s.

- Outflow winds become elevated tonight through Saturday as low pressure treks south of Haida Gwaii.

SHORT TERM.../through the weekend/

A weak surface feature in the central gulf continues to weaken and get absorbed into a stronger feature moving south into Haida Gwaii through the evening timeframe. To replace this low pressure in the gulf is a higher amplitude ridge over northern British Columbia and the Yukon overnight tonight. Between the high pressure in the Yukon from this ridge, and the stronger low passing south, northerly winds are expected to strengthen through the night. Not expecting strong influence from katabatic winds, as the cold pool in Canada is still relatively warm, hovering around 21 degrees between 925-850 mb. Regardless, land areas exposed to northerlies, such as Skagway, could see wind gusts as high as 30 mph overnight tonight and into tomorrow. Finally, expect to see this clearing of skies to last through at least the weekend.

Temperatures are the big headache for this forecast, as with the clearing skies, radiative cooling could bring temperatures much lower than expected. For now, temperatures in the Icy Strait corridor and northern inner channels are hovering near the mid to upper 20s in sheltered areas, and the low 30s for areas with wind. Juneau and Petersburg could see some patchy fog overnight, with Juneau fog, if it develops, likely to deposit as frost rather than stick around. The same could not be said for Petersburg, as temperatures are expected to stay above freezing. If widespread fog does develop going into Saturday, it may stay for much longer than anticipated from the warming 850 mb temperatures going into the weekend, strengthening the inversion.

LONG TERM

Generally uneventful weather pattern in the extended portion of the forecast, wrapping up October neatly. A ridge of high pressure in the Gulf will be the main feature driving the weather in SE AK. Offshore flow will lead to milder weather and limited to no precipitation for much of this week. Early in the week, the feature most worthy of discussing is a small low which intensifies a bit over the southern panhandle and move further south. This will amp up the N-S pressure gradient on Tuesday into Wednesday, increasing northerly winds in Lynn Canal, and potentially other N-S inner channels to a lesser extent.

Later in the week on Friday the next considerable low and attendant fronts will be moving into the Gulf, raising rain chances yet again.

AVIATION.../Through 06z Sunday/

VFR conditions continue as outflow and high pressure remain over the area. This is allowing for mostly clear skies across the panhandle that will continue through the TAF period. As a low pressure system moves south of the area, northern TAF sites, Haines and Skagway, will see increasing winds. Strongest winds are expected early Saturday morning with gusts around 20 to 25 kts. Central TAF locations that do not see these stronger winds have a chance of seeing fog develop tonight. Areas around Angoon are already seeing this fog that has brought lowered visibilities to around 2 SM with ceilings of 200 to 500 ft. Highest confidence for fog would be in the vicinity of Petersburg, Gustavus and Juneau. Although these locations are likely to see periods of fog, they may not see as low of visibility restrictions due to cold overnight temperatures preventing fog from getting very thick. Any fog that does develop will dissipate during Saturday morning allowing for clear skies.

MARINE

Outer waters: A compact low out the Gulf continues to rapidly shift west and weaken with fresh to strong E-ly winds over the northern Gulf and outer coastal waters diminishing through the night and turning more N-ly. Across the southern waters, E-ly winds will increase and and turn more N-ly through the night into Saturday as a stronger low pushes south of Haida Gwaii. Winds will become strong with seas build 7 to 10 ft. Winds and seas diminish across the Gulf and coastal waters Saturday night into Sunday as high pressure moves across the Gulf from W to E as the aforementioned low departs SE towards Vancouver Island. Winds and seas will increase early next week as high pressure builds back into the western Gulf and increases the gradient as low pressure develop to the south, with winds becoming fresh to possibly strong from the northwest, especially over the southern waters.

Inside Waters: Increasing offshore winds and seas tonight as strengthening low pressure moves south of the area. Fresh to strong northerly winds and seas 4 to 5 ft through the north/south oriented channels through tomorrow as the gradient remains tighter across the panhandle. Fresh to strong easterly outflow winds could also develop across Taku Inlet and Stikine Sound. Winds and seas lessen Saturday night into Sunday as the pressure gradient turns more parallel to the panhandle as high pressure moving across the Gulf and inner channels by Sunday evening. Winds and seas looks to increase again early next week with as high pressure builds back into the northern Gulf and increases the gradient as low pressure develops to the south, with northerly/easterly offshore winds possibly becoming fresh to strong.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-033-036-641-642-661-662.