textproduct: Juneau

UPDATE

Aviation Discussion For 06z TAF Issuance.

SYNOPSIS

Key Messages:

-No major weather concerns expected through the early week, however marine layer low clouds will persist over the eastern Gulf and inner channels.

-Light rain and drizzle for the northern Gulf Coast and northern panhandle continue into midweek. No heavy rainfall is expected. -High pressure over the eastern Gulf of Alaska will keep the southern panhandle dry through at least mid week.

LONG TERM.../Friday through Tuesday/

The ridge of high pressure in the Gulf of Alaska looks to begin to break down into the weekend. Overall, the weather pattern still looks fairly benign, but there could be some convective showers forming in British Columbia with easterly flow aloft Saturday. Right now, instability in the Alaska Panhandle looks quite low, so this should limit chances of this activity approaching Southeast Alaska.

With model discrepancies this far out, there is still uncertainty as to where the best chances for precipitation will set-up. Any precipitation that does form looks to have fairly low accumulations for the area (less than 0.5").

AVIATION

/through 06z Thursday/ High pressure over the Gulf of Alaska will edge ever so slightly northeast over the next 24 hours, but not enough to significantly alter the running aviation pattern. For the northern panhandle, MVFR to VFR flight conditions continue this evening with CIGS AoB 4000ft and VIS greater than 6sm. Moving into the overnight period, expecting return of MVFR to IFR CIGS along the northern terminals including PAGS and PAYA as the marine layer builds back in along the Icy Strait Corridor. Likely see a similar situation tomorrow morning with slow clearing with low end VFR to upper end MVFR prevailing by 18 to 21z Wednesday with CIGS AoB 5000ft. Strongest winds through the afternoon expected near Skagway with sustained winds 15 to 20kts with occasional gusts up to 25 kts possible. Elsewhere, winds are expected to remain 10 to 15 kt, with isolated gusts up to 20 kt, primarily along Lynn Canal.

For the southern panhandle, cloud cover is expected to fill in overnight as low as 1000 ft along the outer coast, lowering flight conditions to MVFR/IFR, before recovering again in the morning with some clouds lifting. Overall can expect primarily mid to higher level overcast by the afternoon Wednesday with relatively benign winds once more.

MARINE

Outside: Tuesday morning, ASCAT wind passes highlight moderate winds out of the northwest along the coast, with a clear signature of the dominate surface high in the east-central Gulf. The exception is Cape St. Elias, where a low near Kodiak is bringing south to southeasterly flow of moderate breezes. Expect a continuation of what we have seen the last few days, with daily freshening up of the northwest winds to fresh breezes, especially near and downwind of prominent capes of the Alexander Archipelago.

Moving on to sea state, a variety of wave systems are impacting the gulf. The dominate groups are wind waves at 7 to 8 seconds, with southerly wind waves of 2 to 4 ft impacting Cape St. Elias, becoming west-northwest as you move toward the Fairweather Grounds and south toward Dixon. These wind waves are burying southerly swell at 15 seconds of 1 to 2 ft. Moving through the next few days anticipate similar wave regimes, with the freshening of the afternoon winds building seas 4 to 6 ft; highest seas near Prince of Wales/Dixon, burying underlying southerly swell.

Fog continues to come into play along the coast near Cape Spencer south to Edgecumbe. Expect areas of dense fog with visibility dropping below 1nm at times, favoring the late overnight/early morning hours.

Inside: Another great day for chasing fish. Primary threat for mariners moving around the region is daily afternoon sea breezes, freshening up the winds to moderate to strong breezes (15 to 25 knots) for some select areas. Focus for the highest winds continues to be western Icy Strait (Dundas Bay west to Cross Sound) and northern Lynn Canal into Taiya; furthermore, southwest winds near 10 to 15 knots moving up southern Glacier Bay could be slightly problematic for Bartlett Cove and Sitakaday Narrows. For the remainder of the Panhandle, winds of gentle to moderate breezes (10 to 15 knots) are forecasted. Wind waves remain 2 to 4 ft, highest seas near Cross Sound and northern Lynn Canal. A note on this..

For the northern region, ebbing tides after 1800 AKDT will coincide with the strongest west to south winds, which could bring locally higher seas. Mariners navigating the Inian Passes and major ocean entrances in the evenings should keep this in mind; our wave forecast does not take into consideration the combined effects of wind and tide. Northwest winds in Clarence Strait early this afternoon and a flooding tide could also generate locally higher seas for a few hours. While not overly concerning for larger open ocean vessels, this could bring unwelcome surprises for folks in small skiffs/sea kayaks.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...None.