textproduct: Juneau

SYNOPSIS

Key Messages:

- Mostly sunny skies with warm conditions will remain in place through the rest of the weekend. With cooler temperatures along the immediate coast lines due to onshore flow/sea breezes.

- Conditions will be warmer Saturday with highs in the low 80s away from the immediate coast for southern portions of SE AK. Elsewhere highs are expected to be in the upper 60s to mid 70s.

- A slight chance of isolated thunderstorms for areas east of the Ketchikan-Wrangell line remains for Saturday afternoon.

LONG TERM.../Monday through Friday/

The forecast for next week remains consistent, featuring persistent ridging while we monitor a disturbance in the Gulf that could bring precipitation to the region. Guidance indicates a strengthening upper-level low forming over the Gulf and tracking eastward across Southeast Alaska. A weak mid-level low developing between Monday and Tuesday will assist precipitation formation in the northern panhandle, while a ridge maintains its hold over the southern region.

While upper-level forcing appears to be minimal, a shift to onshore flow Monday afternoon, triggered by a weak low traversing the western Gulf, will likely support orographically driven precipitation over the northern/central panhandle on Tuesday and encroachment of the marine layer further inland overnight and into the morning. This activity will be supported by lingering low-level instability carrying over from the weekend's warm temperatures. Current thinking is that models may be slightly overestimating rainfall accumulations, especially following the recent drier stretch, so backing off on raising QPF amounts at this time. While there is uncertainty regarding the exact placement of the Gulf low, precipitation will be typical for the season, with high confidence that daily accumulations will remain at or less than 0.10 inches and mainly impact the northeast Gulf coast, near Yakutat.

The southern panhandle is forecast to retain a warmer and drier trend as it remains more centrally positioned under the surface ridge. By Friday, the ridge will likely break down as a weak surface trough moves through, supported by an upper-level trough and jet streak, bringing more organized rain showers back across the entire panhandle.

AVIATION

VFR conditions across the area this afternoon, although a marine layer is lingering just offshore of Yakutat. Otherwise, sea breeze winds remain predominant through the remainder of the daytime hours on Friday. Expect the marine layer to push back in overnight and bring CIGS to at or near IFR (700-1500 feet) across the outer coast, and potentially even into Gustavus. The marine layer will then once again clear out through the daytime hours on Saturday. A few thunderstorms may be possible in the Misty Fjords and the vicinity of Skagway, but otherwise, expect the usual sea breeze influences (NW flow for Ketchikan, SW flow for Juneau Airport, enhanced S flow for Skagway etc) to be the main weather-related concern.

MARINE

Inside Waters: A ridge building along the outer coast will steer prevailing flow out of the N for most of the inner channels barring Lynn Canal. Prevailing northerly flow for N/S channels will remain between 5 to 15 kt for most locations through the remainder of the week and into the weekend. The exceptions will be Clarence Strait, which will see 10-20 kt NW winds, and northern Lynn Canal, Taiya Inlet, which at times will see S 15-25 kt winds.

E/W channels will see prevailing westerly winds. Sea breeze influences will strengthen winds during the late afternoon and evening hours around Icy Strait and Point Couverden to 15-20 kt through the weekend, with wind speeds then slowly diminishing during the overnight hours.

The chance of a few isolated thunderstorms can't be ruled out on Saturday for locations east of Ketchikan including Behm Canal and Portland Canal.

Outside Coastal Waters: NW winds prevail through the weekend, as a ridge strengthens over the Gulf. The strongest winds (20-25 kt) remain along the SE Gulf Coast, where waveheights of 6 to 8 ft linger through the weekend. Lower waveheights of 3-6 ft are expected for the northern Gulf during this timeframe. S swell of 1-2 ft for the northern Gulf becoming sharply W or NW as one heads into the eastern Gulf.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ641-642-661-662.