Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
842 FXAK67 PAJK 220002 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 402 PM AKDT Sat Sep 21 2024 .SHORT TERM...A low pressure system continues to weaken as it moves over the panhandle. With this, expect winds and rain to continue to lighten tonight before another strong low enters the gulf Sunday. For the rest of today, winds will diminish to fresh breezes along the inner channels, if not already lightened. Stevens Passage and Clarance Strait will be the last channels to see decreasing winds. A short break in rain will begin late tonight into tomorrow morning as a short lived ridge moves through. The next impact will be Sunday night into Monday as a low sets up in the 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 rain across the panhandle. For more information on precipitation see the hydrology section. The tightening pressure gradient with this low create gale strength winds along the gulf coast Sunday evening. These tighter gradients allow for strong breezes to occur in the inside waters. The low pressure system then continues to sit in the gulf keeping winds elevated. These winds do not start to diminish until Monday night when the gradient finally 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...Conditions this afternoon ranging from below minimums to better than 3000/5 around the Panhandle. Meanwhile the northeast gulf coast is clear & 7. Those excellent flying conditions are forecast to spread south and slightly east such that Panhandle locations from Chatham Strait/Lynn Canal westward should see 3000/5 or better tomorrow. Instrument conditions still expected along the Coast Mountains. Marginal conditions from the ice field west to Chatham Strait. The break in the weather will come to a close by Sunday evening as the next front arrives with lower conditions, heavy rain and more LLWS/turbulence. && .MARINE...There will a short break for the gulf and inner channels as non-impactful winds occur Saturday afternoon and night before the next low pressure system enter the gulf Sunday. A tightening pressure gradient with this 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...Small Craft Advisory for PKZ031-036-641>643-652-661>664-671-672. && $$ SHORT TERM...EAB LONG TERM....AP AVIATION...Fritsch Visit us at http://www.weather.gov/Juneau