textproduct: Juneau

SYNOPSIS

Key Messages:

- A low pressure system remains over the southern gulf bringing showers into the southern and central panhandle.

- Expect increased marine winds, mainly over the southern gulf and Clarence Strait, Thursday into Friday.

- A ridge builds over the gulf Friday into Saturday allowing for winds to weaken and precipitation chances to decrease.

LONG TERM.../Saturday through Wednesday/

At the start of the long term period a low will be situated over the southeastern Gulf of Alaska. The associated frontal system will extend over the southern portions of the panhandle and will bring light rain showers along the Coastal Range as well as for communities Petersburg south. While the low will is expected to remain mostly stationary the strength of which will weaken through the weekend which will result decreasing rain chances through the weekend. For the northern panhandle easterly flow will dominate, and while chances of precipitation is lower compared to areas to the south, it is non zero. That said, precipitation for the northern areas is expected to be more showery in nature. Due to the low weakening the chance of thunderstorms that were mentioned in the previous forecast discussion seem to becoming less likely. That said, the thunderstorm chances will have to be monitored closely as it will be very dependent on the exact track and strength of the low.

Looking towards the start of the next week, models are in agreement that a ridge will move into the Eastern Gulf. The exact amplitude and placement of the ridge axis is still a little bit uncertain, however it will dictate where the generalized onshore flow and wetter conditions will be placed. The current line of thinking is that these conditions will be Icy Bay westward on Monday and will move east through through mid week.

AVIATION

A couple of changes to the ongoing forecast, mainly in regards to cloud cover and fog in the northern half of the panhandle. Most notably, northeast drying flow over the Coast Mountains are slow to clear clouds in the Icy Strait corridor and northern inner channels, although they are still expected to clear in the next few hours. Certainly there is evidence of this over water of clearing, but just enough moisture is lifting orographically that continued cloud cover persists. The second being fog chances overnight, as dewpoints are not expected to substantially fall between now and overnight. With clearing skies, expecting at least some fog to develop, with at least IFR conditions for the aforementioned areas. While it is possible, did not have the confidence to introduce LIFR VIS for the northern half TAF sites.

MARINE

Outer Waters: The outside waters forecast is dominated by the seasonably strong low pressure on the southwest portion of Haida Gwaii, and the associated front moving up from the north. This front is largely expected to stall over Prince of Wales Island, generating strong breezes to near gale southeasterlies for the gulf waters, and up to 20 knots for Clarence Strait through Thursday, and decaying Thursday night. Due to the longer fetch and duration, wave heights exceeding 8 ft are likely in the aforementioned areas. Expecting to see strong wind waves from this system, not much in terms of swell from far off systems. Going into the weekend, we look to return to a weaker high pressure pattern, with broad northwesterlies in the gulf waters.

Inside waters: Mostly benign conditions with winds generally 10 knots or less. Expecting to see a broad switch from southeasterlies to northerlies tonight as the front approaches the southern panhandle. Could see some overnight fog development in areas sheltered from northerly winds, such as parts of Icy Strait and Stephens Passage. Clarence Strait is expected to stay elevated for longer, with the possibility of a southerly surge Friday morning, up to around Frederick Sound.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ641-642-661>663.