textproduct: Juneau

UPDATE

Quick forecast update and 18Z Aviation update

Primary focus Saturday morning remains in elevated northerly winds in Lynn Canal along with potential for thunderstorms this evening. Expect strong breezes (22 to 27 knots) to persist in Lynn before diminishing later this late afternoon. Thunderstorm forecast remains a tricky endeavor, with more favorable conditions focused in the central Panhandle; at the time of this AFD we have placed 15 percent chance across the higher terrain in the central region. Threats associated with these cells will be gusty winds, periods of heavier rain, and the chance for a lightning strike or two.

AVIATION.../through Sunday afternoon/...Currently, an MVFR cloud deck is positioned over the southern half of the region and is forecast to expand northward into the central panhandle this afternoon. CIGs in the south will fluctuate near 3000 ft as showers advance from the south, dropping lower during heavier downpours alongside potential VSBY reductions. The progression of the frontal band into the central panhandle will combine with higher terrain to trigger gusty winds and more convective showers. Behind this front, conditions in the southern panhandle are expected to improve, likely reaching VFR by late today with only isolated, light rain remaining. A southerly wind shift is anticipated this afternoon as cooler air moves in behind the initial frontal band. Meanwhile, northern TAF sites will experience predominantly VFR conditions. Northerly prevailing winds driven by pressure gradient forcing will increase from this morning into midday before shifting back to a sea breeze direction this afternoon with increased daytime heating. Winds in the south begin to increase tomorrow (15-20 kts in Clarence Strait) as an easterly wave approaches.

PREV DISCUSSION......ISSUED AT 455 AM AKDT JUL 25 2026

SYNOPSIS...

Key Messages:

- Warmer and drier with decreasing clouds across the northern panhandle Saturday.

- Rain returning from the south and progressing northward late Saturday afternoon and into Sunday.

- Multiple systems move through the area next week, bringing rain to the area.

SHORT TERM.../through Sunday night/...The surface low continues to slide south away from the panhandle this morning and will stall this afternoon. While clearing is occurring across the north, abundant marine layer clouds persists across the southern panhandle. North of the low, downslope winds and offshore flow winds will bring drier air and clearing across the north today, with partial clearing across the south through early afternoon. The low will then meander off the coast in the eastern Gulf through the weekend with multiple shortwaves rotating around the low and into the panhandle. An easterly wave approaches the southern portions of the area late Saturday afternoon, and will progress northward during the overnight hours and into Sunday morning before stalling out. Rain will generally be light, however, there will be potential for some heavier showers with gusty winds along the leading edge of the lifting wave with colder temps aloft and a pocket of weak instability, along with some modest forcing along the boundary, especially during the peak daytime heating hours this afternoon. Kept thunderstorms out of the forecast for now as the convective nature of the rain will be limited.

In addition to the rain, some gusty northerly winds for the northern communities is likely due to a tightening of the pressure gradient as the wave moves through.

Warmer temperatures today due to the offshore flow and clearing skies, especially across the north, with afternoon temps in the 60s and possibly reaching 70. Slightly cooler for Sunday due to the increase in clouds and lingering rain.

While conditions will improve by Sunday night as the wave drifts north and weakens, southerly flow and weak waves along the eastern flank of the low out in the Gulf will keep the threat of showers into early next week.

LONG TERM.../Monday through Friday/...The low pressure system near Haida Gwaii is expected to meander westward before another low forms near Prince William Sound. The secondary low near Anchorage is expected to move southward, and push the initial low closer to the Alaska Panhandle next week. This means that a fairly wet weather pattern is expected through next week.

However, the exact placement of these low pressure systems will dictate who has the highest chances for rain and strongest winds across Southeast Alaska. As of now, the Southern Panhandle looks to have the highest rain chances, and perhaps some stronger winds (up to 20 kts) in Clarence Strait. Overall, the rainfall totals don't look particularly impactful, but it will be monitored for future forecast updates.

MARINE... Outer Coastal Waters: A broad surface low has settled east of Dixon Entrance this morning and has turned the prevailing wind direction to be N-NE. The pressure gradient across the region was very weak overnight allowing seas and wind speeds to decrease or remain steady. As the low lingers to the south and higher pressure builds over the Yukon, some northerly outflow winds are possible for Yakutat Bay and along the northern gulf coast, but have limited the sustained winds in these areas to 15 kt due to the time of year and lack of cold air to accelerate the winds through the passes. Looking ahead to Monday, a trough digging into the gulf from the west will cause the surface low to the south to redevelop and strengthen. Winds in vicinity of Dixon Entrance and Clarence Strait were increased to 25kt for Monday and may need to be extended further into Tuesday.

Inner Channels: Largely light and variable winds across the inner channels overnight, however northerlies are starting to tick up this morning across the northern inner channels. As high pressure continues to rise in the Yukon and pressure is falling across the south, expect the northerly winds to be the prevailing direction. Some models were favoring much stronger winds (25-30kt) for places like Eldred Rock and out of the northern arms of Glacier Bay, but based on the time of year and no cold air driving the winds, have opted to reduce the peak winds in these areas by about 5kt. As a result, the small craft advisory was cancelled for N. Lynn. Another factor to lowering the wind speeds is the sea breeze influence that should be a factor this afternoon to counter the north wind for Lynn Canal. Conversely, the sea breeze (glacier breeze) will likely be enhanced for Glacier Bay and Yakutat Bay this afternoon. For the southern inner channels, the N-NE outflow winds this morning will veer to the SE through the afternoon as a colder airmass develops under the low pressure and rain showers help to drive it down, causing winds to shift out of the SE. As frontal bands progressively track northward over the weekend, the wind direction will shift out of the SE for the rest of the area and may see some gusty winds as that occurs in the showers.

AJK WATCHES/WARNINGS/ADVISORIES

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