textproduct: Juneau

SYNOPSIS

Key Messages:

- Cold temperatures continue, with many areas seeing single digits to teens for overnight lows. Northern Lynn Canal is still expected to dip below zero. Dangerously cold wind chills continue along White Pass.

- Continued strong outflow winds will keep the cold air in place through the weekend for the northern panhandle. Marginally warmer air moves into the southern panhandle this weekend with snow becoming likely.

- A point of uncertainty in the weekend snow forecast is how far north the moisture will be able to push. The farther the moisture travels, the more colder and drier air it has to contend with. But if the moisture is able to push through, significant snowfall is possible as far north as the Icy Strait corridor.

- Farther south, there is a possibility that enough warmer air could push far enough north that the snow could switch to rain for areas south of Sumner Strait.

LONG TERM.../Friday through Monday/

Only minor changes were made to the long term forecast, mainly adjusting outflow wind timing and beginning to narrow down timing on the potential snow for next weekend into early next week.

The main impacts for the long term remains the temperatures and winds. The arctic boundary sits just south of the panhandle through the rest of the week, keeping below freezing temperatures through much of the extended forecast. Daytime highs will struggle to reach into the 20s for many locations in the northern and central panhandle, and into the 30s for the southern panhandle. Overnight lows during the week will mostly stay in the single digits up north and in the 10s down south, slightly increasing through the weekend as the next system moves in. Strong outflow also persists through the week, with 20 to 35 kt winds and pockets of gales blowing through the inner channels and funneling out into the coastal waters of the gulf. The strongest winds will remain in the northern panhandle, particularly down Lynn Canal and Stephens Passage as well as out of Cross Sound, with gaps along the gulf coast serving as outlets for strong winds to funnel through. There will be a brief decrease in wind speeds on Friday, though Lynn Canal will still stay above 20 kts before outflow ramps up even stronger than before going into the weekend. Strong gales are expected to spread through a majority of the inner channels, with strongest winds remaining in those hot spots in the northern panhandle. Freezing spray will remain an issue in the inner channels and along the NE gulf coast with these elevated winds, which could become heavy at times.

Precipitation is expected to return to the forecast Saturday morning as a low jumps into the southern gulf and sends a front northward into the panhandle. The precipitation will mainly impact the southern panhandle starting Saturday, extending north to the central and potentially the Icy Strait Corridor including Juneau through Sunday into next week. Uncertainty still remains in how far this front will make it up the panhandle, as persisting outflow winds will attempt to force the front to stay more south. The other area of uncertainty is the southern panhandle temperatures through the weekend, as models are starting to depict the arctic boundary shifting just north of this area allowing the front to bring temperatures in the mid to upper 30s to some of these southern locations. This makes snow potential even more uncertain, as there may be times where these temperatures reach above freezing enough to turn to a rain/snow mix or even just rain for periods. This boundary looks to shift back down south into early next week, keeping the cold temperature trend in the extended forecast.

With colder temperatures remaining through the long term forecast, precipitation will most likely fall as snow for the northern panhandle. Active weather looks to remain into early next week.

AVIATION

Offshore flow continues across the panhandle, keeping VFR conditions and clear skies across the majority of the panhandle, the only areas with cloud cover being parts of the central and southern panhandle extending from the low to the south. These areas remain VFR however, with the exception of Petersburg having some drops to MVFR after still seeing some snow showers and CIGs down to 2500 ft this morning, however this will diminish into the morning with the central panhandle improving to VFR conditions. These VFR conditions will remain across the panhandle throughout today and into tonight as offshore flow remains keeping most lower clouds offshore to the south around the low.

The biggest concern for aviation this morning continues to be the outflow in the northern panhandle, with Haines and Skagway continuing to see increased winds and gusty conditions, before the outflow begins to weaken into midday. The winds in Skagway will stay around 20 kts with gusts to 35 kt, steadily decreasing by around 20Z as the high in Canada to the north/northeast slowly moves more to the east while the low to the south of the panhandle stays to the south into this evening. At this time winds will diminish to 10 to 15 kt with less strong outflow by Skagway near the surface, before increasing again by 06z tonight to 20 - 25 kt as the N-S gradient begins to tighten again over the northern panhandle. This is as another wave approaches the panhandle into Saturday, bringing back stronger outflow conditions once again into the end of the TAF period. Juneau continues to see some wind shear and NE 25 to 35 kt cross barrier flow, however this will diminish into midday.

MARINE

Outside: Northeasterly outflow wind speeds decrease tonight. Then, outflow gap winds increase again, up to around 35-45 kt, for the same areas for the weekend. Some freezing spray is possible for the northeastern gulf.

Inside: The outflow pattern continues through Friday with an overall weakening trend. The tighter pressure gradient in the north will keep wind speeds up to 30 to 35 kt for most of Lynn Canal. Near the Icy Strait area and south, wind speeds will decrease tonight and Friday as the gradient weakens. Friday night into Saturday, wind speeds pick back up to 25 to 35 kts, with near 35 to 40 kts back in Lynn Canal as a low pressure system tracks northward, tightening the pressure gradient over SE AK. Wind directions will, more-or-less, go unchanged through this time frame. These winds will also be accompanied by fully-developed seas up to 14 ft subsiding as the winds weaken.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Extreme Cold Warning until 9 AM AKST this morning for AKZ318. Strong Wind until 6 AM AKST early this morning for AKZ318. Cold Weather Advisory until 9 AM AKST this morning for AKZ319. Winter Storm Watch from Saturday morning through Sunday morning for AKZ326>330-332. Winter Storm Watch from Saturday morning through Monday morning for AKZ331. MARINE...Heavy Freezing Spray Warning for PKZ012. Heavy Freezing Spray Warning for PKZ031. Gale Warning for PKZ012. Small Craft Advisory for PKZ011-013-021-031>033-053-641>644-651- 661>664-671.