textproduct: Juneau

UPDATE

Updated the Aviation section for 18z 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.

-A weak trough aloft my trigger some Light rain and drizzle Thursday afternoon and evening while a stronger trough advances into the southern panhandle Friday, and to the northern half of the panhandle Friday night.

-The filling basin for the Mendenhall GLOF, continues to be monitored as the basin is continuing to slowly fill.

LONG TERM

/ issued Wednesday / A fairly benign weather pattern is expected to continue throughout the next week, with temperatures remaining relatively steady across the region. High temperatures will generally range from the low to mid-60s, with lower 70s possible for inland areas late this week and early weekend, and no significant warming or cooling trends are anticipated. The ridge in the Gulf will continue to maintain a stout marine layer along the Gulf Coast, causing widespread overcast skies due to a saturated and stable surface layer. However, only occasional drizzle is expected, as there is a lack of upper-level support for more efficient precipitation formation.

The panhandle should remain mostly dry until the weekend and into early next week, as a weakening upper ridge and surface high pressure allow more energy to pass into the region. While there is a shift in coastal flow from northwesterly to southeasterly winds beginning Sunday, we are lacking the strong easterly flow necessary to push thunderstorms into our region. That said, light to moderate rain showers may impact the southern panhandle and inland border regions, from Hyder to Skagway, driven by terrain influences and possible convection from western Canada. Looking ahead to the start of next week, there is currently low confidence in the placement and total amount of seasonably heavier precipitation, as model guidance remains in disagreement over the track of a weak low in the western Gulf. We will continue to watch this development in the coming days.

AVIATION

Only minor changes to the ongoing forecast, both adjusting for current conditions and penciling in worse conditions for tonight for the Icy Strait corridor. Still seeing mostly VFR conditions with CIGs around 3500 to 4500 ft in the inner waters for most of the panhandle, with LIFR to IFR CIGs for the outer coast and parts of Icy Strait, AoB 1000 ft. Expecting to see conditions improve this morning for most areas, but CIGs may not exceed 2500 ft. Currently expecting conditions for the NE gulf coast and Icy Strait over to Gustavus to return to at least IFR conditions, with CIGs AoB 900 ft after midnight tonight. Could see some nearby fog as well, but confidence is low that this will advect over TAF sites at this time. It is possible to see some lower CIGs to MVFR for the Ketchikan area very late in the TAF period from the incoming system from the south, but did not include in this TAF issuance.

Skagway continues to follow the diurnal gustiness trend for another day, with wind gusts not expected to exceed 30 knots from the south. No LLWS concerns for the incoming system tomorrow moving up from the south.

MARINE

Outside: High pressure remains consistent in the gulf, so there is not much that has changed with the forecast. Winds in the outer waters were adjusted down slightly, not expected to reach over 15 kts through Thursday with a west to northwesterly direction as you move south along the coast. Higher winds are likely to be located around prominent capes along the coast as winds are funneled around them from the NW. This pattern is likely to continue through the weekend, with winds becoming even lighter and more variable on Saturday.

Inside: Not much has changed with the forecast for the inner channels, with sea breezes being the prominent forcing for the wind through the weekend. Lynn Canal is likely to see the highest wind, with a 10% chance that they will exceed 20kts on Thursday. The most likely scenario is that the wind will be around 10-15kts and reach up to 17kts in Taiya Inlet, both with a strong southerly component. A similar set up is expected through the weekend for Lynn Canal and Taiya Inlet. Otherwise, winds across the panhandle are expected to follow a sea breeze trend, but remain below 10kts due to cloud cover and the lack of daytime heating through the weekend.

AJK WATCHES/WARNINGS/ADVISORIES

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