textproduct: Juneau

SYNOPSIS

Key Messages:

- Gusty winds continue this evening with gales for northern Lynn Canal and a Wind Advisory for Skagway. Winds are likely to diminish late tonight into Thursday.

- Multiple systems to impact the region late week into the weekend, with the potential for heavy rain, gusty winds and increasing seas.

- Cooler but seasonable temperatures for the period, with daytime highs generally in the 50s.

LONG TERM.../Friday through Wednesday/

Upper level features continue to show a rather active pattern through the long range period. We start out with the formation of a broad upper trough stretching from the Russian Far East to NW Canada on Friday. The trough is anchored by an upper low moving out of Russia late week that eventually positions itself over SW mainland Alaska. The broad trough stays in place into early next week, but several short waves are evident rotating around the southern edge of it. There are indications that the trough may break down by mid next week, but there is not much agreement on that scenario yet.

The active weather pattern is still apparent at the surface with a series of fronts expected to move through the region late week, through the weekend, and into early next week. First the low and front that is approaching on Friday is still there, but details are still being worked out. The trend so far with it is still setting Friday up to be wet (up to 1 to 3 inches of rain Fri morning to Sat morning) and breezy (winds of 15 to 25 kt for the SE gulf and inside waters) regardless.

The weekend into early next week is looking interesting as well with a strong broad area of low pressure moving into the gulf from the SW and heading toward the northern gulf coast. In addition to the stronger onshore SW flow it will bring, it its wake is a shot of cooler air that will be coming in from the west. Forecast convective indices are already indicating that Sunday into Monday may be rather convective/showery in nature as the cooler air moves in and the potential is there for some thunderstorms across a large area of the gulf and outer coast at that time. Retained the area of slight chance thunder that was put in yesterday, but also added some areas of chance of thunderstorms along the higher terrain along the outer coast. This system is also looking rather wet and breezy with strong SW to W flow across the gulf into the panhandle and an organized front enhancing the rainfall Saturday night into Sunday morning.

Damp weather continues into the first half of next week with onshore flow continuing, but showers and W to SW winds will not be as strong. There are indications of more systems moving into the gulf next week, but there is no consensus on when or where yet.

AVIATION

With the main front having pushed further down the panhandle, conditions have improved to VFR across the northeast gulf coast as of Wednesday afternoon. Strong winds continue for Lynn Canal through the afternoon and evening, with some rain also making its way up into the area though primary impact remains lowered CIGs. The heaviest rains are behind us, and further lowered VIS is primarily due to low CIGs combined with relatively light precipitation. The central outer coast will see this into the evening before some improvement is expected later tonight. For the southern inside TAF sites as well as Juneau, a brief period of fog or low stratus development is expected early tomorrow morning due to saturation from the recent rains as well as diminishing surface winds. For Juneau, this will also depend on any potential thinning of the cloud deck overnight to allow for more cooling. Overall improved conditions by mid to late morning Thursday with slight chance for showers as flow shifts onshore from the SSE from the next system approaching the gulf. No further LLWS expected through the TAF period, just residual strong southerly winds through the afternoon and early evening.

MARINE

Outside Waters: As the front tracks east across the panhandle this afternoon, winds shifting from SW to W have maintained fresh to strong breezes, though begin to quickly drop off tonight through Thursday as the front exits the region. Winds begin to increase again to moderate to fresh S to SE-ly Thursday night as a strengthening low lifts north into the Gulf. Wave heights between 8 to 11 ft in the central and northern Gulf today begin diminishing overnight to 4 to 6 ft by Thursday. Seas build again late Thursday night across the eastern Gulf as the next low pressure system tracks north Friday. Seas near ocean entrances building to 5 to 6 feet, and up to 12 ft near the northern outer coastal waters.

Inside Channels: With the passage of the front, the strongest winds have been observed near the intersection of Southern Lynn Canal, Icy Strait and Northern Chatham Strait this afternoon, with near gale sustained winds and gusts to 50 kts. Afternoon gales in North Lynn Canal decreasing to 25 to 30 kt this evening, and to 15 to 20 kt by tomorrow morning. Elsewhere, winds are expected to decrease and become light to gentle across the panhandle as the front shifts south and weakens. Predominately S to SE-ly winds will begin to increase across the region late Thursday night as the next low pressure system pushes north into the Gulf. Winds increasing to fresh to strong by Friday afternoon with wave heights building to 3 to 4 feet within the larger N-S oriented channels.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory until 7 PM AKDT this evening for AKZ318. MARINE...Gale Warning for PKZ012. Small Craft Advisory for PKZ013-021-022-032-643-644-651-652- 662>664-671-672.