textproduct: Juneau

SYNOPSIS

Key Messages:

- Benign pattern continues with nocturnal marine layer developing overnight and diurnal afternoon sea breezes through early next week.

- Occasional rain showers possible for parts of SE AK Sunday into Monday. Light rain amounts expected Wednesday and Thursday over much of the area.

LONG TERM.../Wednesday through Saturday/

A new low moving into the Bering Sea to start the week will eventually be the impetus for deteriorating conditions for most of the panhandle into midweek. A front extending from the Bering low will serve to initially weaken the ridge over the Gulf Tuesday, with the upper level ridge also shifting eastward over British Columbia. On Wednesday, the NE coast and panhandle north of Sitka could still be dealing with some light lingering showers or drizzle, but the main story is an elongated low moving up from the central Pacific. This feature is set to spin up in the space between two surface highs over the central and eastern Pacific, and quickly race northward Wednesday. In the process, the moisture tap from the central pacific will quickly be shut off as it passes beyond 40 degrees N.

While no longer having a long fetch of moisture to draw from, this system is expected to produce rain rates above normal for this time of year. The highest storm totals are expected along the outer coast from the northern half of Prince of Wales Island northward to Baranof Island, though this could shift based upon the track of this feature wobbling east or west, as some disagreement in guidance remains. As of this discussion, areas from Icy Strait southward have a greater than 45% chance of seeing 24 hour rain totals greater than 0.25 inches from Wednesday through Thursday from this system. A smaller area, from southern Baranof northeastward towards Kake and Petersburg, have approx a 50% chance to see 24 hour rain totals of 0.75 inches or more. Temperatures are expected to remain warm enough such that precipitation will fall as all rain at sea level.

Winds will generally remain on the lighter side through the period with the strongest associated with any afternoon sea breezes that develop. The primary influence from these afternoon sea breezes will be changes in direction from overnight winds, though areas such as Taiya Inlet could see more gusty winds. With the elongated nature of this system, a relatively sharp wind shift from north to south is likely over the eastern gulf Wednesday into Thursday. However sustained winds are expected only up to fresh breeze (17 to 21 kt) with lighter winds over the inner channels. A ridge is then expected to build in behind this feature to end the week before another short wave tries to once again push through from the west late Friday into Saturday. Model disagreement continues to increase heading into next weekend as to whether the ridge will hold strong or break down relatively quickly.

AVIATION.../Until 12Z Tuesday/

The marine layer will persist for the northern Outer Coast & into the Icy Strait Corridor through the period, keeping CIGs down to within the MVFR flight category. Elsewhere, expect primarily VFR conditions through the period. As far as LLWS values are concerned, those remain benign through the period. SFC winds will also get a bit breezy/gusty from the south for the northern Lynn Canal area, including PAGY, for this afternoon through the evening hours. For Clarence Strait, including PAKT, SFC wind magnitudes will be a bit enhanced out of the northwest for late this morning through the afternoon hours.

MARINE

Outside Coastal Waters: Through the first half of Monday, little change to the forecast as ridging continues over the eastern gulf, keeping coastal winds relatively calm with the exception of the southeastern gulf coast from Cape Decision through Dixon Entrance and the far northern coast to the west of Icy Bay. The southeastern gulf coast is seeing northwesterly fresh breezes with wave heights of 7 to 10 ft flow through Dixon Entrance and down Hecate Strait, which will persist through Monday. Stronger northwesterly winds in the southeastern gulf will last through Monday night. Wave heights remain 7 to 9 ft in the eastern gulf, while initially subsiding through the day on Monday for the northern gulf before rapidly increasing Monday night as a front moves across, also bringing with it SE winds of strong breeze to near gale for these locations. By Tuesday morning prevailing flow across the gulf will be out of the SE, though winds and waves subside Tuesday afternoon and evening. Southwesterly swell of 2 to 4 ft at a period of 10 to 12 seconds will increase to 5 to 7 ft late Monday into Tuesday.

Inside (Inner Channels): Inner channel winds remain under 15 kt through Monday, with the exception of a few places. The southern inner channels will see northwesterly fresh breezes persist with the strongest areas being along the coast of Prince of Wales Island, the Southern Chatham and Sumner Straits channel entrances, and flowing out of southern Clarence Strait. Winds veer out of the south on Tuesday as a weak front moves in, bringing S flow up to 20 kt (fresh to strong breeze) for many of the North/South channels.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ641-642-644-652-661>664-671-672.