textproduct: Juneau

SYNOPSIS

Key Messages:

- Weather pattern change continues through Friday night , with showers diminishing in coverage through the day.

- Another low pressure system brings increased winds and precipitation to SE AK Saturday.

- Outflow pattern allows for drier and colder weather Sunday into next week. This will also bring strong winds over northern SE AK.

LONG TERM

One main area of interest going into this weekend and next week. That being the arctic cold front moving from north to south on Monday, bringing the panhandle finally back into cold temperatures.

Beyond this, by Monday, a stout inversion in Canada, enhanced from the sharp ridge and NW flow aloft, look to bring forth strong katabatic flow to the northern half of the panhandle. Little change in overall message going forward for the Monday time range. Pressure gradients between Juneau and Skagway look to be around 8-9 mb, with large density differences look to bring forth up to gales. At this time, there is around a 25% chance of storm force winds based on similar historical pressure gradients in this channel. Expecting to see similar conditions in the upper arms of Glacier Bay. Similarly, gradients between Juneau and Ketchikan look to support up to gale force winds down Stephens Passage. Couple of caveats to this forecast: how fast and strong are the cold temperatures going to filter southward, and how long will the stronger winds stick around out of the north. At this time, not looking to see cold temperatures supportive of any moderate or greater freezing spray late Sunday night for the far northern inner channels. Then, expecting moderate freezing spray chances to move south over the day, making the most progress overnight. Looking to see freezing spray chances extend as far south as southern Stephens Passage and just south of Point Couverden.

Beyond Monday, things get a tad more complicated. At this point, there is around a 60% chance for pressure gradients to moderate, in part due to a flatter ridge aloft. While this would keep temperatures much colder, it would relax winds significantly even by up to 10 knots. Unfortunately, since temperatures are anticipated to be so cold at this point, moderate freezing spray is still a possibility, even with wind speeds less than 30 knots. That being said, there is a 40% chance, mainly represented in the GEFS, for a dominant high amplitude ridge, which would keep the stronger winds in place, and bringing down the moderate or greater freezing spray chances much further down than currently anticipated.

AVIATION

MVFR to VFR conditions are predominant across most of SE AK as shower coverage diminishes in the wake of a recent low. While showers will largely disappear entirely overnight, expect stratus and low fog to develop in some locations and the central inner channels, including the Icy Strait Corridor, resulting in hit or miss IFR conditions. Fog that does form should linger through much the first half of Friday morning, before dissipating, though the outlier chance that fog may last longer around the Icy Strait Corridor does exist. Anticipate MVFR and VFR conditions for the southern panhandle and northern panhandle generally for Saturday, with lower CIGS areas around the Icy Strait Corridor.

MARINE

Inside (Inner Channels): As these winds decrease Friday afternoon, fog is becoming more likely for Friday night into Saturday morning. If fog does develop, it will most likely be over the central to northern inner channels. Looking further into the end of the weekend, and to the start of next week, an extended period of outflow conditions begins. This will bring gale force conditions throughout many of the inner channels, with the strongest winds most likely over Lynn Canal. Along with these strong winds, decreasing temperatures will allow for freezing spray to develop, mainly over the northern inside waters.

Outside (Gulf and Coastal Waters): Broad W-ly on-shore flow will turn NW-ly as ridging moves into the Gulf from a strengthening surface high over the NW Pacific. Conditions will deteriorate starting Saturday night as the next system will take a southeast transit along our northern Gulf coast, bringing gale force northwest winds to the central gulf and fresh seas increasing and lasting through Sunday. Anticipating this to be a quick moving system, departing SE out of the panhandle towards the Pacific Northwest by Monday morning with strong off- shore/outflow conditions quickly developing into Monday afternoon. Mariners transiting along the N Gulf early next week should remain aware of areas of strong winds out of outflow prone areas like Cross Sound, Yakutat Bay, Disenchantment Bay, Alsek River Valley, and the Dangerous River Valley.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...High Wind Watch from late Sunday night through Monday morning for AKZ325. MARINE...Small Craft Advisory for PKZ022-053-641>644-651-652-661>664-671- 672.