textproduct: Juneau

LONGER TERM...NEXT WEEK

With the first fall storm system now having moved through SEAK, our eyes start turning to the next significant weather system. Ensembles and deterministic model guidance over the past few runs have been in fair agreement with deepening a rather impactful/strong area of low pressure (potentially as low as 960 mb) over the northwestern GulfAK Tuesday, with a rather large/extensive area of storm force winds (48-55 kts) and seas in excess of 20 ft extending well east of that low center into the eastern GulfAK and along the outer coast from Cape Spencer northward. This is something maritime interests will have to closely monitor as we go into early next week, and especially for those transiting the GulfAK. See marine discussion below. As for impacts to SEAK specifically, the front extending east of that low will push across SEAK Tuesday through midweek, bringing another round of potentially heavy rainfall and strong gusty winds to the outer coastal areas. Stay tuned as we go through the weekend on further developments with this Gulf storm system. 05/Garmon

AVIATION

The last location to report Gale Force gusts was Tree Point to the southeast of Ketchikan and south of Misty Fjords at 1 PM. For the remainder of the TAF sites, winds have diminished significantly the past few hours and ceilings are mostly in the VFR to MVFR ranges. We continue with a large area of rain across the central/southern portions of the Panhandle, with a few thunderstorms that developed in the afternoon hours just east of Yakutat (about 20 miles east) and to the east of Ketchikan into Misty Fjords. Chances for impacts to airports from thunderstorms are small, although there are a few isolated cells out there across the southern Panhandle, about 100 miles east of Sitka over the GulfAK. We expect the isolated thunderstorm activity to diminish toward evening, and we expect mostly MVFR to VFR overnight in areas of mostly light rain/ceilings. Question is, how much fog can happen overnight, especially if we clear out behind the front? Right now guidance is not pinging on fog production given light mixing and cloudcover, however some localized fog is not out of the question. 05/Garmon

MARINE

Outer waters:

The low pressure system sitting in the northern gulf is swinging across yet another frontal system, generating 25-30 knot southerlies in the gulf waters through tonight. A shift to the southwest with similar wind speeds is expected during the early morning hours for the coastal zones before diminishing through Saturday night. Wave heights associated with the southwesterlies are expected to build to around 15 ft offshore between Cape Spencer and Cape Edgecombe. May also see some convective cells with some lightning strikes and stronger wind gusts. The low pressure, then vertically stacked, should slowly fill and move southeast, keeping up to 20 knot westerlies for Sunday morning before diminishing. Going into next week (Tuesday/Wednesday), a potent low moves into the central gulf, as noted in the long term section. Current guidance indicated a barrier jet looks to form along the NE gulf coast, generating storm force winds east of Cape St. Elias. Currently, there is good confidence on the strength of the system; however, confidence on timing and placement is moderate to low. There is evidence in ensembles that new low centers will generate along the negatively tilted shortwave aloft, which would move around the low. These types of scenarios would shift highest wind speeds much further down the coast, to around Cape Spencer at the furthest with current guidance. For waveheights, very strong southwesterly swell upwards of 22 ft will contribute to wave heights exceeding 25 ft in the gulf waters. Stay tuned for more information regarding this system.

Inside Waters:

Leading into the front, building high pressure in the southern panhandle in wake of the stronger front that moved through the southern portion of Clarence Strait may decouple winds. This combined with clearing skies and abundant moisture from recent showers may generate some fog overnight tonight ahead of the incoming front. The front from the aforementioned low pressure in the central gulf is expected to bring up southeast winds early Saturday morning to around 20-25 knots. Highest wind speeds, and associated small craft advisories, look to be for Lynn Canal and Stephens Passage. Definitely possibly to see an upgrade to 25 knot winds for northern Chatham Strait, but did not have the confidence for this forecast package.

HYDROLOGY

With the end of the larger atmospheric river system this morning, flooding concerns are no longer expected, even as some showers continue into the weekend. Rivers and creeks may still be at their crest into this evening, but overall most streams have crested by the morning / afternoon and all are expected to continue to fall into tonight and the weekend. Any showers that continue this weekend will be largely light, and even if some more productive cells bring periods of higher rainfall amounts, they will be quick moving and not persistent, with longer breaks between even the more organized bands of showers.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-022-031-053-641>644-651-652- 661>664-671-672.