textproduct: Juneau

SYNOPSIS

Key Messages: -Another band of stronger snow showers moves through the central panhandle and Icy Strait Corridor through the day on Friday, but snow totals will be limited in some locations by daytime heating.

-A Stronger system arrives early Saturday morning, bringing more snow, wind, and rain.

-Additional fronts move up through the remainder of the weekend.

LONG TERM

A deep upper level trough oriented over interior Alaska down into the Gulf, sitting just to the west of the panhandle, continues to enable the onshore flow into SE AK. The cold air coming down into the westward side of the trough into the low center over the northern Gulf, alongside multiple shortwaves with bands of vorticity, allow for the more showery activity to continue moving into the panhandle this weekend. There will be a more organized wave moving through Saturday into Sunday from S to N as a surface gale force low in the central Gulf and approaches the panhandle from the west. This low will bring a front into the coastline Saturday, pushing north through the day and into the night. This will follow shortly behind a decent wave of showers on Friday, and will be followed by showers soon after the front passes, with the heaviest precipitation for these showers Sunday into early next week being across the southern panhandle and outer coastline up to Sitka.

The front will bring some more uniform snowfall amounts compared to the more showery pattern that has been ongoing, with moderate to heavy precipitation expected across much of the panhandle. With the warmer temperatures and longer daylight hours, much of the southern panhandle will see more potential for rain. The amount of accumulating snowfall from this front and the following showers into Monday remain more uncertain across the coast and southern half of the panhandle for this reason. Wile the majority of the onshore moisture flow and the vorticity maximum aloft are expected to move over the southern panhandle this weekend, keeping the potential for significant snow accumulations in the forecast, the warmer temperatures at the surface may not allow for as much accumulation overall even while temperatures aloft stay cooler.

While the warmer temperatures will remain into early next week across the southern panhandle, colder temperatures aloft remain as well, allowing for some higher potential for some mixing during the day and accumulating snow Monday and Tuesday as showers continue to move into the area. The northern panhandle is looking to see more of a clearing trend Monday into Tuesday as outflow begins to set up, however the timing and potential for showers still remain uncertain. About half of the ensemble clusters support a drier solution in the north, with elevated outflow winds as a stronger low moves in more to the south of the panhandle and as the upper level trough begins to break down and move eastward. The other solution is for the low to remain further west and not break down or weaken yet, allowing for the surface low to linger more along the outer coastline than staying to the south, keeping some potential for showers across more of the panhandle than just the southern half. Overall just something to watch for if this pattern change will happen and when it will happen next week, if it will be as soon as Monday/Tuesday or if the current pattern will hold out longer.

AVIATION

/through 12z Saturday/ Variable flight conditions this morning as scattered snow showers continuing to stream SW to NE across the panhandle. VFR flight conditions have generally prevailed overnight, however we've been continuing the trend of quick drops down to IFR/LIFR visbys and MVFR level CIGS within the passing snow showers. Moving into this afternoon, anticipating the same trends, predominate VFR conditions will prevail with scattered to numerous snow showers continuing to track inland with CIGS AoA 4000ft. Brief periods of LIFR/IFR visbys as low as 1/2SM are expected through the period within any heavier snow showers. Tried to time the incoming shortwaves through the afternoon with TEMPO groups, one currently along the W coast of Baranof will slide E through the late morning, pushing into Hoonah, Gustavus, and Juneau between 18z to 00z this afternoon. Looking into Friday night, a stronger more organized frontal system will push into the southern panhandle by 06 to 09z this evening, bringing another round of moderate to heavy precipitation to the area with reduced visbys down to IFR once more.

Winds through the period will remain light, around 10kts or less, but can't rule out an isolated gust up to 20kts through the afternoon. No significant LLWS expected through the period, but will see low level SE-ly winds begin to increase after 09z across the S Panhandle up to around 30 to 35kts.

MARINE

Inner Channels...Southerly winds will trend back upwards as another area of stronger winds is expected for the central inner channels midday Friday (up to 20 kt this time) from a second short wave that will be moving through at that time. Finally winds will be starting to increase yet again late Friday night (this time up to 25 to 35 kt for most areas (except the far north) as we start to see effects from the next frontal band moving in. Needless to say that seas will be up and down as wind increase and then decrease through the next 36 hours. Not expecting anything higher then around 7 ft for most areas though, with the exception of ocean entrances.

Gulf Waters...Mostly 25 kt winds or less early Friday around the gulf from a S to SW direction give way to S to SE winds reaching gale force 35 to 40 kt by late Friday night as a front moves onshore. Another low moving north late Saturday will see another round of gales, especially along the low's southern The shower activity is making things more complex as the heavier showers are causing brief periods of increased gusts as they move through. Seas are around 8 to 12 ft (swell is around 9 ft out of the SW with a period of 10 sec), and will trend upward through Friday night towards 10 to 14 feet.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Winter Storm Watch from late tonight through Saturday evening for AKZ317>327. Winter Weather Advisory until 7 PM AKDT this evening for AKZ320>323. Wind Advisory from 7 AM to 7 PM AKDT Saturday for AKZ328>330-332. MARINE...Gale Warning for PKZ641-644-661-664-671. Small Craft Advisory for PKZ021-022-031>036-053-642-643-651-652- 662-663-672.