textproduct: Juneau

SYNOPSIS

Key Messages:

- Heavy rain continuing through Tuesday for northern panhandle. Flood watches remain in effect.

- Wind gusts ranging from 40-60 mph reported overnight with highest gusts near Yakutat, Skagway, and Juneau. Strong wind gusts continue through Thursday afternoon with widespread Wind Advisories and High Wind Warning in effect for Skagway.

- Mariners, a sharp Westerly wind shift expected from west to east Tuesday into Tuesday night with isolated Thunderstorms continuing through Tuesday and overnight into Wednesday across the Northern Gulf.

LONG TERM.../Thursday through Sunday/

Onshore flow with at times moderate showers continue for Thursday with the stacked but weakening low lingering over the northern Gulf. The low will shift southeast and weaken further Thursday night into Friday, with showers diminishing from north to south across the panhandle. Any lingering showers across the southern panhandle should by Friday afternoon. A few lingering snow showers possible for Thursday along the Klondike Highway and the upper reaches of the Haines Highway but any accumulations would be minimal. As the low departs to the southeast, ensemble and deterministic guidance generally show upper-level ridge over mainland Alaska shifting east and settling over SEAK Friday into the weekend, with clearing skies and drier offshore flow developing. Gusty northerly winds could develop along the northern highway into Lynn Canal. Daytime highs will remain in the 40s throughout the period, with overnight lows in the 30s.

AVIATION../through Wednesday morning/

A low pressure system in the Gulf continues to rapidly intensify. Early this morning, an initial front progressing across the panhandle has brought strong, gusty winds along the outer coast, as well as moderate to heavy rain to sites along the NE Gulf coast and within the Icy Strait Corridor. Around 10Z, frequent lightning strikes detected off the coast near the Fairweather Range gradually moved inland, with both PAGS and PAJN reporting TS. Lightning will persist across the Fairweather Range and between PAYA and PAJN for the next few hours, with a slight chance continuing off the NE Gulf Coast throughout the day.

Moderate to severe turbulence is widespread across the northern and central panhandle. Additionally, several sites in this area will likely experience LLWS as a N-S oriented low-level jet surges eastward today. The bulk of this shear will occur from this morning into early afternoon following the initial front and a secondary front, which is expected to reach the outer coast by 21Z. This passage will prompt a swift shift in wind direction and speed, transitioning from stronger (20-30 kt) southerlies to weaker (5-15 kt) westerlies. Due to the unstable nature of this system, surface winds will respond quickly to mixing from the 925mb level, shortening the duration of LLWS. Nevertheless, this frontal passage remains a heightened threat to all aviators traversing the region.

After the second front passes through later this evening, wind speeds and rain rates will rapidly diminish. Behind the front, ongoing onshore flow will keep most of the region under MVFR conditions (CIGs between 1500 and 2500 ft), though brief breaks in cloud cover will emerge as precipitation becomes more showery.

MARINE

/through Wednesday night/

Outer waters: Strong system continues to progress into the NE Gulf coast this morning. Satellite derived winds show wind swath of sustained Gales 35 to 45 kts SW-ly across much of the central Gulf and SE-ly along the coast from Port Alexander northward to Cape Suckling. In tandem, satellite derived wave heights indicating wave forecast remains large area of 15 to 18 ft seas over the central Gulf progressing NE towards the Gulf, expecting this to continue building reaching 20 to 25 ft from Yakutat Bay down to Point Edgecumbe through early Tuesday afternoon. Anticipate a sharp wind shift to predominate W-SW through early Tuesday afternoon as front progresses eastward. Lastly, thunderstorms remain possible across the N Gulf coast from Yakutat southward to Cape Edgecumbe through Tuesday afternoon. With any thunderstorm, anticipate erratic winds and periods of limited visibilities from heavy rainfall. By Wednesday morning, winds and seas diminish as a broad area moves E from Prince William Sound over the N Gulf, with broad SW- ly winds 15 to 25kts expected and seas subsiding 8 to 11 ft by late Wednesday night.

Inside Waters: Widespread strong winds across the inner channels the morning, with ongoing observations of gales of 35 kts in Lynn Canal, Stephens Passage, and Point Gardner. Inner channel marine conditions will remain hazardous through Tuesday afternoon as a strong front pushes inland, with continuation of sustained small craft to gale force winds expected with periods of storm force gusts possible. Forecast wave heights within the inner channels remain elevated through Tuesday afternoon, between 4 to 8 feet with highest within Lynn Canal and Stephens Passage. A gradual diminishing trend by Tuesday evening and persisting into Wednesday morning. Likeliest hold out on elevated winds will be Stephens Passage and Lynn Canal until WEdnesday afternoon, as winds lax from parallel pressure gradient to the N/S channels.

HYDROLOGY.../through Tuesday night/

Heavy rain continues for the panhandle this morning with rain rates continuing to remain around 0.2-0.3 inches per hour. Some stations have reported up to half an inch of rain this morning as well. With the continued rain, rivers have started to respond but so far none are too concerning. Farther south, the rain has been on the lighter side so accumulations have not been as significant. The heaviest rain is expected to persist for the northern panhandle this morning before starting to shift south. As the rain shifts to the south, it will start to exit the area faster and help to limit rain totals for the southern panhandle. For the northern panhandle, another 1-3 inches of rain looks to be possible through late tonight. Farther south, amounts will be limited to closer to 1 inch, especially for places south of Sumner Strait.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Flood Watch through late tonight for AKZ317-320-322-325. Wind Advisory until 7 PM AKDT this evening for AKZ317. High Wind Warning until 10 PM AKDT this evening for AKZ318. Wind Advisory from 10 PM this evening to 10 AM AKDT Wednesday for AKZ318. Wind Advisory until 4 AM AKDT Wednesday for AKZ319. Wind Advisory until 10 PM AKDT this evening for AKZ320>325-327. Wind Advisory until 1 AM AKDT Wednesday for AKZ328. Wind Advisory from 10 AM this morning to 4 AM AKDT Wednesday for AKZ330-332. MARINE...Gale Warning for PKZ011>013-021-022-031>036-053-641>644-651-652- 661>664-671-672.