textproduct: Juneau

SYNOPSIS

Key Messages:

-No major weather concerns expected into the weekend. Periods of light rain and overcast skies continue through Sunday. Highs reach into the mid to upper 60s Saturday, warmer temperatures expected Sunday.

-Marine layer low clouds will persist over the eastern Gulf and inner channels through the weekend. -Suicide Basin glacier dammed Lake continues to fill, at this time it is expected to be full sometime August 10th or 11th. In the past, it has taken up to 6 days for the main flooding event to start after the basin is full. Visit weather.gov/ajk/suicidebasin for more information.

LONG TERM

/Tuesday through Thursday night/ Ensemble models have reached greater consensus on the track of the main system for next week. A weak upper-level trough is expected to move over the area Monday and Tuesday, bringing light, and generally unimpactful precipitation. A mid-level low will supply vorticity to the region Monday and Tuesday, amplifying anticipated rain showers before tapering off as high pressure builds on Wednesday. A significant upper-level ridge will build on Wednesday, while the low-level ridge strengthens early next week as the low tracks south and east toward the AOR. High pressure remains the dominant feature, keeping the main low to the west as it tracks over the Aleutians, digs south, and moves into the Kenai Peninsula. While the current expectation is for the main frontal precipitation to push through on Tuesday with a mean 24 hour accumulation of 0.25 (supported by the 75th percentile NBM and GEFS/EC ensemble agreement), there remains a risk that if the low shifts further east, Yakutat and surrounding areas could experience heavier bands of rain showers between Thursday and Friday. For now, the expected track will keep the Northeast Gulf Coast under light rain showers, but nothing unseasonable. After the midweek system pushes through, the central and southern panhandle are expected to see clearer skies, and therefore warmer temperatures. Current thinking puts inland and southern areas with highs in the low 70s for Wednesday and Thursday.

AVIATION

/through 12z Sunday/

Upper level system continues to work its way northward out of the Pacific towards the Panhandle this morning keeping a wide variety of flight conditions across the area. A band of showers stretches east/west across the central panhandle from just north of Sitka to the Icy Strait Corridor with light rain and IFR ceilings AoB 1000ft reported at Gustavus, Hoonah, and Juneau. Through Saturday morning, expecting band of light rain to remain near stationary across the panhandle before weakening and gradually dissipating through 21z this afternoon. With surface high parked over the central Gulf in tandem with the upper level low, overcast skies and unsettled weather will continue through the TAF period. Conditions improve during the afternoon to VFR/MVFR with CIGS AoA 4000ft, however diminish routinely overnight AoB 2000ft as marine layer settles in and light rain returns.

Winds across the panhandle remain light this morning, widespread 5kts or less. Similar to previous days, expecting them to increase in the coming hours, reaching sustained 10 to 15kts this afternoon, can't rule out a gust up to 20kts under any seabreeze influences. No LLWS concerns through the TAF period.

MARINE

Outside: A 1023mb high pressure continues to take residence over the Gulf through Sunday, keeping overcast skies with light and variable winds along the coast and outer waters, 10kts or less. Wave heights remain largely benign through the early week, around 4ft or less along the coast. Main marine concern for outer and coastal waters will be nightly return of marine layer, dropping visibilities as low as one quarter mile each morning. If pattern serves like the previous few days, Cape Spencer near entrance to Cross Sound and northward to the Fairweather grounds will likely see some areas of patchy dense fog Saturday morning and once again Sunday morning.

Inside: Conditions across the inner waters remain calm this morning, with overcast skies and light rain with winds largely 10 kts or less. Not seeing a real driving force for winds through Saturday, outside of the usual daily sea breeze. As per usual, will likely see strongest winds in Lynn Canal northward to Taiya Inlet with sustained southerly winds 10 to 15kts, potentially a gust up to 20kts. Wave heights remain 4 feet or less through early week.

HYDROLOGY

Suicide basin glacier dammed lake continues to fill. The pool elevation as of 9 pm Friday was at 1343 ft with a rate of rise of around 2 ft over the last few days. The overflow channel is at an elevation of around 1350 ft so the lake has another 7 ft to rise before it starts to overflow across the side of the glacier. With the rate of rise over the last few days and weather conditions expected to remain mostly consistent with cloud cover and near normal temperatures the lake is expected to likely become full around August 10th or 11th. Once that point is reached, in the past it has taken up to 6 days before the lake starts releasing.

AJK WATCHES/WARNINGS/ADVISORIES

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