textproduct: Juneau

UPDATE

after the 06z TAF issuance. Not any big changes to the forecast. Easterly flow with the main band over the central panhandle. Observations, put ceilings between 1000 and 6000 feet, with isolated ceilings a touch lower. In showers, visibilities occasionally lowering in the showers.

PREV DISCUSSION......ISSUED AT 428 pm AKDT Jun 4

SYNOPSIS...

Key Messages:

- Rain continues into Friday as a low passes south of the panhandle

- Chances of showers linger into the weekend with seasonably cool temperatures

- Leaning towards drier and slightly warmer conditions for early next week

SHORT TERM...An organized band of light to moderate rain continues to move northward across SE AK with showers following behind. So far rain rates have remained lower, around 0.02 to 0.05 inches per hour, with the heaviest rates around 0.1 inches per hour. These higher rates, along with the highest rain totals, have been located over the Sitka area. Areas to the north can anticipate similar conditions as the front moves northward. An exception to this is near Yakutat where drier conditions will continue with increasing cloud cover. Then later this evening the front will start to move southward once again as it weakens. This is due to the parent low pressure system moving eastward and also weakening. At this time an area of higher pressure moves eastward into the central gulf with another low following close behind, in the northwest gulf. Because of continued onshore flow, light showers will continue through the start of the weekend.

Looking into winds, the strongest winds will be located near Skagway as low pressure to the north, and higher pressure to the south create a strong pressure gradient. This will create stronger southerly winds with gusts up to 30 to 35 mph tonight. Winds will slightly weaken tomorrow morning before once again increasing during the afternoon. Another area of stronger winds are anticipated over the southern panhandle, especially near Clarence Strait tomorrow through tonight as the low pressure moves eastward. In other areas breezy conditions are anticipated across the area with rain showers.

LONG TERM.../Sunday through Wednesday/...Deterministic and ensemble guidance are still not in complete agreement on the details for the end of the upcoming weekend. However, the overall pattern tends to keep the jetstream in more zonal flow and south of the Gulf of Alaska. Moving down to 500 mb, models are also in relative agreement on an upper level low moving eastward from the Aleutians will phase with a shortwave trough sliding southward from over the Bering Sea. At the surface, a cold front extending from a low south of the Aleutians will progress eastward and attempt to form a closed surface circulation south of Kodiak Island by late Saturday.

With the expected lack of upper air support, any low that forms is expected to be vertically stacked almost upon inception, and struggle to produce significant hazardous weather over the region. Continuing from inherited forecast, rain seems most likely to be limited the panhandle south of the Icy Strait Corridor and once again be predominantly light in terms of total accumulations. With the expected closed circulation aloft, this system is expected to linger over the Gulf into early next week before gradually dissipating as ridging tries to build in from the south. This will however mean light onshore flow and continued shower potential, mainly for the outer coast. This will be looked at further in the coming days to see if the drying trend in model guidance continues.

With the continued onshore flow, temperatures will remain seasonably cool over the weekend with daytime highs ranging from the mid 50s in the north to mid 60s in the south. By early next week there will be some slight warming as the ridge takes over and should help clear out some of the residual cloud cover heading into midweek. Snow levels also look to remain above 4000 ft, which means many mountain tops and ridge lines should continue to see gradually retreating snow lines through the period.

AVIATION.../Until 00Z Saturday/...A band of rain & lower CIGs originating from an area of low pressure centered to the southwest of the panhandle are continuing to move from over the Southeast Alaska region. This will continue on & off through the TAF period. The band will periodically lower CIGs &/or VISs down to the MVFR/IFR flight category range through the period. SFC winds will be on the rather breezy/gusty side through this evening for the northern Lynn Canal(PAGY & PAHN) area, especially for PAGY, due to a tightened north to south pressure gradient in place over that area. SFC winds look to become a little bit elevated for the PAKT area through this afternoon, as well. LLWS values remain relatively benign through the TAF period.

MARINE...A low south of the Panhandle will continue to slowly move eastward into British Columbia through the remainder of the work-week. A band of rain rotating around said low will linger over the panhandle before dissipating & falling apart through Friday. A ridge of high pressure builds-in over the eastern Gulf for late work-week & into the weekend. Then, another low & associated front approach the Panhandle for the latter half of the weekend.

Outside Waters(Eastern Gulf of Alaska): Small craft advisory level significant wave heights continue over the southeastern Gulf through late Thursday night as a low to the south of the Panhandle moves eastward. By Friday, seas in the outer coastal waters of 5 to 7 feet are expected. Seas will remain between 5 & 7 ft until Sunday when significant wave heights build back to between 8 & 10 feet when another low & associated front approach Southeast Alaska. Southwesterly swell of 2 to 4 ft is expected through Thursday night, with the largest swell in the southern Outer Coastal waters. The swell will diminish to 1 to 2 feet on Friday.

Inside Waters(Southeast Alaskan Inner Channels): Winds over most of the Inner Channels will stay around 15 kt or less through the Weekend, with wind speeds spiking upwards as a rain band passes over areas through through Friday. Lynn Canal and Clarence Strait will likely remain on the breezier side, with these areas likely to see sustained winds of up to around 20 kt & spiking up to around 25 kt in the case of Northern Lynn Canal & the ocean entrance area of Clarence Strait. On Sunday winds will increase to around 20 to 25 kt & seas will build, once again, as another low & its associated front approach Southeast Alaska.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-641-644-651-652-661-672.