textproduct: Juneau

SYNOPSIS

Key Messages:

- Shower potential shifts southeastward and diminishes through Wednesday afternoon, with skies clearing behind. Northerly winds build across the inner channels Thursday. - High pressure returns through the end of the week with drier conditions, more sunshine, and high temperatures in the mid 60s to low 70s.

LONG TERM.../Friday through Monday/

No major changes to be seen in the extended forecast with a ridge of high pressure building in over the gulf come Friday. This will finally dislodge the weak troughing over the panhandle and usher in more consistent dry conditions this weekend and overall benign weather. As mentioned in previous discussions, a tightening gradient early Friday favoring north south oriented channels is expected to bring about some stout northerly winds. However these should quickly diminish through the afternoon hours Friday with winds across the inner channels and coastal waters largely falling to 10 kt or less. With the drier conditions, localized sea breezes are expected through the weekend but should not be particularly impactful.

The main question in the long term remains whether a low develops in the northern gulf to take a swipe at the northern panhandle early next week. Models are still not sold on the idea, though there is a slight trend for a majority of the associated precipitation to remain over the interior. Overall though the main takeaway is still for another round of more summer-like weather this weekend with fairly dry conditions and daytime highs to rebound to the mid 60s to around 70 for most of the panhandle.

AVIATION.../Through 00Z Friday/

A low pressure system moving SE along the Gulf Coast has brought some showers across the Alaska Panhandle. Heavier showers have brought brief periods of MVFR ceilings, and IFR visibilities. This activity has mostly impacted the Northern Panhandle, and may impact Petersburg and Wrangell through 05Z Thursday. As a ridge builds in behind the trough, fog is possible across the Alaska Panhandle tonight. Fog potential appears highest for Petersburg and Wrangell.

With the ridge developing tonight, and the low continuing southeastward, this will lead to an increasing pressure gradient for the Northern Panhandle. The strongest winds are expected for Lynn Canal, where northerly gusts up to 30 kts are possible. After 20Z Thursday, conditions are expected to be generally VFR. For Juneau and Gustavus, sea breezes are expected to develop Thursday after 18Z.

MARINE

Outer waters: Generally downward trend through the tonight period, as the front exists into southern British Columbia. Wave heights, driven by prolonged strong winds and a modest westerly swell look to diminish from 8-12 ft at 9 seconds to 4-5 ft by Friday night at around 15 seconds with very little swell influence. Expecting to see highest wave heights and wind speeds out of Chatham Strait and into Dixon Entrance from unseasonably strong northerlies, before falling off Friday morning.

Inside Waters: Main story through Friday is a transition from southerly winds to northerly tonight, strengthening through the day Thursday, and peaking overnight Thursday night into Friday. High pressure from a cold front in Canada, in combination with a shortwave trough moving down from the Yukon, look to increase northerlies in north south facing channels like Lynn Canal, Chatham Strait, and Stephens Passage. Expanded out the areas of strong breezes to exit Chatham Strait into the gulf, but notably did not increase Lynn Canal up to gale force. Pressure gradients for this area look to approach around a 7 mb difference between Whitehorse and Juneau, which has historically only caused gale force winds 20% of the time. Therefore, kept gales out of the forecast, as the more likely scenario will be Lynn Canal maximizing around 30 knots

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-013-022-032-033-641>644-651- 661>664-671-672.