Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
592 FXAK67 PAJK 221255 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 455 AM AKDT Sun Sep 22 2024 .SHORT TERM.../through Sunday night/... Quick Notes: -A short-lived break in the rainy weather today. -Light winds will be found are the area as well. -Front later today brings back the heavy rain and stronger winds tonight. Details: A short break in rain is in the forecast for SE AK today. Current satellite loop shows clouds trying to thin out so if that trend is able to continue, parts of the area may end up with a sunny Sunday. The next round of heavy rain moves in tonight as a low sets up in the western gulf, allowing for rain and wind to move back into the panhandle. Rain will begin Sunday evening along the coast before it quickly becomes widespread across the panhandle. For more information on precipitation see the hydrology section. The tightening pressure gradient with this low will create gale force winds along the gulf coast Sunday evening. These tighter gradients will also allow for strong breezes to occur in the inside waters. The low pressure system will stay in the gulf, keeping winds elevated. These winds do not start to really diminish until Monday night, when the gradient starts to weaken. .LONG TERM... Monday a deep low in the western Gulf will bring a wide swath of southwest winds across the majority of the central and southern Gulf along with a moderate to strong atmospheric river. Through Tuesday into Wednesday expect the surface pressure gradient to weaken, allowing winds to diminish and swell to decrease. Rain continues. See Marine section for higher detail info. Early Thursday, attention turns to a possible gale force low moving north from the coast of Haida Gwaii, with ensembles highlighting a low transiting along our coast before making landfall in the Central Panhandle. If ensemble solutions hold the course this has the potential to be for our first High Wind Watch of the season for the far southern Panhandle. Mariners planning on transiting from and to southeast Alaska along the Inside Passage should take notice, as Dixon Entrance into Clarence Strait are under the gun to see near 35 knots of southerly wind, with more extreme outliers suggesting 50 knots. With the position of the low expect northerly flow in the northern inner channels and easterly near-gale force coming out of Cross Sound. Dont anchor on previous wind forecasts, changes will be made as guidance gets a better handle on the low depth and location. Snow levels continue to follow their seasonal normal, dropping below 5,000ft as we move through the week. No snowfall impacts are currently anticipated at sea level. && .AVIATION... Departing system has left IFR to VFR flight conditions across the panhandle this morning. Anticipating gradual improvement through early afternoon to predominate VFR conditions with CIGS AoB 5000 to 7000ft for much of the area. VFR conditions on Sunday will be short- lived as another system moves into the Gulf of Alaska with rain chances and LLWS increasing from west to east after 00-06z as front pushes inland. Sustained winds should remain less than 15kts through mid afternoon, increasing through tonight up to 20kts with isolated gusts up to 30kts with strongest winds along coastal and southern panhandle TAF sites. Likeliest locations for mechanical turbulence and LLWS across Gulf coast and interior southern panhandle by Sunday evening into Monday morning. && .MARINE... A tightening pressure gradient with the next low will create gale force winds, organizing out of the southeast, along the gulf coast and into a few of the inner channels. Highest winds along the inner channels are expected in Icy Strait, Cross sound, and Clarence Strait. Winds will stay elevated from Sunday night through Monday evening before the pressure gradient weakens. The weakening pressure gradient will allow winds to decrease to fresh breezes Tuesday. && .HYDROLOGY... Monday into Wednesday will feature a very wet fall storm along with elevated winds. 24-hour rain totals Monday and also Tuesday near 2 to 3 inches are expected. Expect the worst conditions to come in early Monday, featuring 6-hour totals near 1 inch early Monday morning. Heavy rainfall diminishing as we move into Tuesday. Rain continues but at more reasonable rates through Wednesday. Coordination with Environment Canada highlight the uptick in IVT and duration of the AR near Haida Gwaii, with both ensemble mean runs highlighting the potential for an extreme (AR-4) event. While the highest values are likely to miss us, its close enough to warrant some concern in the far south including Hyder. For now the forecasted rain totals represent the most likely outcome. Coordination with the River Forecast center showcases a rise in small streams and creeks but at this time, all major rivers look to remain below flood stage. && .AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Gale Warning for PKZ036-644-651-652-661>664-671-672. Small Craft Advisory for PKZ011-013-021-022-031>035-053-641>643. && $$ SHORT TERM...GJS/EAB LONG TERM....AP AVIATION...NM Visit us at http://www.weather.gov/Juneau