textproduct: Juneau

SYNOPSIS

Key Messages:

- Patchy fog across parts of the panhandle Friday night into Saturday morning

- High confidence of of drier and warmer conditions for Saturday.

- Another system arrives Sunday into Sunday night, bringing a rain/snow mix to the northern half of SE AK, and rain to areas further south.

LONG TERM

The ridging offshore will begin to break down into Sunday as the next system approaches from the NW Gulf. This system still shows colder temperatures aloft that are abnormally cold for this time of year , with -7 to -9 C temperatures at 850 mb and a cold low center at 500 mb. The warmer temperatures at the surface keep some uncertainty on precipitation in the forecast at this time, particularly in regards to how much accumulation is expected. Still expecting this to be a more convective system due to the colder temperatures aloft and warmer sea surface temps, bringing more showery precipitation. This will move into the NE coast overnight Sunday and push eastward across the rest of the panhandle during the morning through the day. Onshore flow and showers will continue behind this front, keeping precipitation across the panhandle through Monday before clearing out from N to S by Monday night into Tuesday. Chances for precipitation will remain across the far southern panhandle Tuesday before clearing up Tuesday evening into Wednesday.

A rain / snow mix is expected in the overnight hours for the N panhandle, becoming rain during the daytime. The southern half of the panhandle will see rain as the system moves through, with some snow mixing in possible overnight, but this is more unlikely than for the northern panhandle due to the warmer temperatures. Any mixed precipitation is not expected to accumulate much at all, especially as daytime temperatures remain in the high 30s to low 40s Monday. Expecting around a trace of snowfall up to 0.5 inches for the northern panhandle Sunday through Monday night, with sea level locations staying below 1 inch for 48 hr snowfall. Chances are higher for the NE Gulf coast and Icy Strait Corridor areas for between 0.5 and 1 inch of snowfall, but much of this would begin to quickly melt into the morning and any snow that falls will be wet and slushy. The southern panhandle may see some snow mixing in, but none is expected to accumulate, and if it does will only be a trace before melting during the day. Majority of the QPF for this system is expected to impact the NE Gulf coastline, between 0.7 to 0.9 inches of QPF for Yakutat, largely falling as rain aside from during the overnight hours early Sunday morning and Sunday night.

AVIATION

A ridge of high pressure continues translating NW to SE across the Alaska Panhandle late today, with a drying trend taking place over the entire panhandle this afternoon, leaving many places in VFR category. Late tonight and into the early morning there is potential for a few northern sites to see fog development. Weak northerly outflow winds are making their way down through the north/south inner channels, with gusts picking up to 25 kts in the wider inner channels north of Juneau. Some model sounding guidance is favoring a decoupling of winds in the boundary layer across the north panhandle including Yakutat, Juneau, and Gustavus, with a low level inversion setting up toward morning. This in conjuction with a cooling, lingering areas of snow, and light winds, points to higher chance that VSBYs can drop to IFR conditions as low as 1/2SM in fog in the previously mentioned sites between 12Z to 16Z. As diurnal mixing kicks in, these low visibility condtions are expected to dissipate with daybreak between 17Z to 19Z.

The southern panhandle will prevail in VFR CIGs at or above 5000 ft through afternoon tomorrow, with a low likelihood for any fog development due to 20 to 25kt winds at 925mb mixing down to the surface and sustaining clear condtions through tomorrow morning.

MARINE

Outside (Gulf and Coastal Waters): Northwesterly winds continue to across the eastern Gulf over the next 24 hours, with speeds of moderate to strong breezes expected overnight Friday into Saturday. Sea state is currently dominated by southwesterly swell of 10 seconds near 5 ft and some chop at 4 seconds. Expect the primary wave height to increase to 6 to 8 ft west of Dixon Entrance by Saturday afternoon. By Saturday evening, winds turn more out of the West, and begin increasing through Sunday, reaching 25 to 30 kt.

Inside (Inner channels): Main threat over the next 24 hours remains northerly outflow winds, with fresh to strong breezes impacting Glacier Bay, Lynn Canal, Chatham Strait, Stephens Passage and Clarence Strait. Freezing spray concerns are limited given warmer air temperatures. Winds begin to relax Saturday night, with southerly winds increasing by Monday as another system moves through SE AK.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-661.