textproduct: Juneau

SYNOPSIS

Key Messages:

- Rain showers likely through the rest of the day Tuesday. Drier at times along the northern gulf coast through Tuesday evening. Another round of showers expected for Wednesday.

- Winds fairly benign across inner channels before increasing with next front approaching Wednesday.

- Temperatures mainly seasonable with highs averaging in the 50s and lows in the mid to low 40s.

LONG TERM.../Thursday through Sunday/

A series of small disturbances and onshore flow will bring steady rain to the region through the end of the week. A weak surface high building over the southeastern Gulf will reinforce onshore flow and could potentially tighten pressure gradients across the panhandle as the next system approaches. A low pressure system originating near Russia will move east, tracking south of the Aleutian Islands and into the Gulf of Alaska by early weekend. There is a growing likelihood of tropical moisture entraining into the system, supported by an 850mb southerly jet, increased precipitable water, and seasonably warmer temperatures aloft. Though this will likely not affect the surface much due to consistent widespread cloud cover and small diurnal trends.

Model spread is still significant, but guidance favors landfall along the north-central coast late weekend. The system could bring rounds of moderate to heavy rain across most of the panhandle, with the highest totals currently expected along the northeast Gulf coast, though this is dependent on the system's exact track and strength. There is also increasing potential for stronger winds and building seas along the outer coast and northern inner channels ahead of this low. While some guidance suggests a more aggressive evolution, the system generally lacks upper level support beyond a weak, negatively tilted trough and jet setup. We will continue to monitor developments through the week.

AVIATION.../through 0Z Thursday/

The weather tracking across Southeast has brought widespread rain, lower ceilings, and localized heavy downpours with degraded visibility to the southern and outer coastal sites, while central and northern inner channels have remained milder with dry to light-rain conditions and prevailing VFR ceilings. This wet, cool system will likely maintain VFR to high end MVFR conditions with occasional rain showers through the period. Mixing in the lower boundary layer has allowed for more persistent southeasterly winds, which is keeping cloud bases elevated around 3,000-5,00ft AGL across the northern and central panhandle. Lower MVFR decks, about 1,500-2,500ft AGL, are likely to remain mostly restricted to the southern panhandle and during periods of heavier shower activity. A brief period of offshore flow Tuesday night could support breaks along the immediate northern gulf coast (PAYA) and could reach as south as PASI. Cloud bases are expected to gradually lower from south to north on Wednesday as southerly winds strengthen ahead of the next system, but overall CIGs are anticipated to hold higher than lower-end model forecasts suggest.

MARINE

Outside (Gulf and Coastal Waters): The system in the eastern gulf continues to weaken Tuesday, with the low center rotating offshore of the northeastern gulf coast. Westerly fresh to strong breezes (17 to 27 kts) and 8 to 9 ft seas persist through the southeastern gulf Tuesday, with fresh breezes (17 to 21 kts) and 6 to 7 ft seas along the gulf coast of Baranof Island and easterly out of Cross Sound. Winds will weaken overnight as the low diminishes, being replaced by a developing low near Prince William Sound Wednesday morning. This will bring southwesterly moderate to fresh breezes (11 to 21 kts) with 6 to 7 ft seas through the gulf Wednesday. Southwesterly 3 to 4 ft swell at a period of 8 to 10 seconds will decrease to 2 ft at 5 to 7 seconds by Thursday, with gulf winds and seas also decreasing by Thursday.

Inside (Inner Channels): South to southeasterly moderate breezes (11 to 16 kts) and 3 ft seas continue for parts of the southern and central inner channels Tuesday, mainly up through Clarence and Sumner Strait and out of Frederick Sound and Stephens Passage. Other than Young Bay holding on to sustained 20 kt easterly winds, the rest of the northern inner channels are relatively light and variable Tuesday. Winds and seas are expected to decrease Tuesday night before jumping back up through midday Wednesday with another system in the western gulf. This frontal passage will bring 15 to 20 kt southerly winds into the northern and central inner channels, with Lynn Canal expected to be closer to 25 kts through Wednesday evening. Seas will also increase to 4 to 5 ft in areas of the strongest winds. Winds and seas will generally diminish Thursday, though Lynn Canal will stay elevated up to 15 to 20 kts into Friday. The southern panhandle will avoid most of these winds through midweek. Ocean entrances exposed to the SW or W will see higher seas up to 7 ft due to W swell invading from the gulf, but those seas will be gradually diminishing Wednesday as swell subsides.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-641-642-661-662.