textproduct: Juneau

SYNOPSIS

Key Messages:

- Somewhat weaker front moves into the panhandle late tonight into Friday morning, increasing rain chances from southwest to northeast.

- Rain and wind diminishes from north to south Friday evening and overnight into Saturday. Chances for rain showers with some breaks for the Fourth of July.

- A stronger low pressure may move near the panhandle late this weekend into early next week.

LONG TERM.../Sunday through mid week/

Main feature of interest continues to be the possibly stronger system on Sunday night into Monday. An unseasonably strong upper level low looks to move towards the southern panhandle, bringing multiple waves of precipitation from south to north. The amount of moisture available is currently nothing to write home about, near normal amounts of precipitable water, however, given the strength of the winds aloft, IVT values are expected to exceed 250 kg/ms. Furthermore, given lapse rates, particularly with the second wrap during the afternoon timeframe, divergence aloft, and plenty of PVA, could see some thunderstorm development with gusty winds and heavy rain. Ultimately, this storm is still relatively uncertain for exactly how it will develop, how each wave will interact with terrain, how far north will strong energy extend, how much clearing will occur in between waves, and will any clear correspond with peak solar heating for higher CAPE values. We will be monitoring this situation carefully for the next couple days.

AVIATION.../Until 0z Saturday/

An upper level low over British Columbia will provide northerly flow aloft into the inner channels through Thursday evening before continuing to slide eastward into Friday. In contrast, southerly flow will continue during this period along Lynn Canal near the surface. This means outside of Skagway itself, Lynn Canal can expect to see CIGs AoB 2000 ft through Thursday evening, with the lowest CIGs around 1000 ft near the Chilkat peninsula, before gradual improvement overnight into Friday as drier air aloft filters in. The panhandle from Sitka southward can expect VFR conditions to continue through the evening with isolated light rain showers. A system approaching the panhandle Friday will bring deteriorating conditions down to MVFR for the panhandle from around the Icy Strait corridor southward, with Gustavus and Juneau likely being on the northern edge of these lowered conditions. At the same time, primarily VFR conditions can be expected further north. There are no LLWS concerns through the period.

MARINE

Outside (Gulf and Coastal Waters): An incoming front moving towards the panhandle will primarily effect the Cape Spencer area and southward. Winds up to 20 knots are possible from the southeast. Particularly around 20 NM west of Cape Spencer, as a tip jet looks to form from winds exiting the Icy Strait area merging with southeasterly winds along the coast. These may exceed 25 knots, but likelihood is low at this time. No dominant swell is present, and with the relatively short duration of winds, not expecting any wave heights meeting or exceeding 7 ft for this event.

Inside (Inner Channels): Mostly benign conditions are expected for most of the inner channels, with the last small craft advisory being cancelled for the Lynn Canal area due to winds continuing to not exceed 20 knots. Ultimately, the inner channels are in a transitory position between the incoming front bringing southeasterly winds and the westerly winds currently weakening. Friday is the day when winds finally shift to the southeasterly for most of the channels, with wind speeds up to 15 knots. Highest uncertainty with this front is the strength of the high pressure near the Juneau area, which could cause upper Stephens Passage to be calm instead of up to 15 knots.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012.