textproduct: Juneau

AVIATION...06z TAFs

Winds are beginning to wind down, with widespread rain showers and CIGs roughly AoA 1500 ft. As winds continue to wind down, turbulent mixing will wind down as well, resulting in lower CIGs and VIS as rain continues. Overnight, could see IFR conditions for the outer coast and the southern half of the panhandle. Overnight, there is evidence of a dry slot in between the first and second front, which may cause some low clouds and LIFR from radiant cooling. Confidence is low on these clouds developing, but the chance is present.

Still seeing the possibility of thunderstorms come early Tuesday, the secondary frontal wrap of this system for the southern panhandle looks significantly more convective. With at least some daytime heating from a dry slot before the convective showers, could see some erratic wind gusts and towers over PoW Island and over to Rev and Annette Island.

PREV DISCUSSION......ISSUED AT

SYNOPSIS...

Key Messages:

- Wind Advisories are posted for the southern Alaska Panhandle to the early evening.

- Periods of heavy rainfall expected across the southernmost zones of Southeast Alaska late this afternoon into the evening hours...but rain rates appear to remain below Flash Flood and Flood criteria levels. We will actively need to monitor rain rates in the south through the evening hours.

- A second wrap of the frontal band around the low approaches Prince of Wales Island, with a semi organized band of stronger showers with potentially gusty outflows from the stronger cells.

SHORT TERM...Slight chances to the ongoing forecast, mainly revolving around the potential for thunderstorms. For today, the frontal passage currently responsible for the frontal passage moving over the panhandle continues to bring moderate to occasionally heavy rain to parts of the southern and central panhandle. Once again, no flooding is currently expected; however, small creeks and streams may rise rapidly. As this frontal passage moves into Canada, a secondary wrap will develop, currently somewhat visible on satellite at time of writing. With a fresh injection of cold air, lapse rates may exceed 8 degrees/km with CAPE values possibly exceeding 500 J/kg. While this may not seem like much by either central Alaska or CONUS standards, this is not climatologically normal for SE AK. Modest effective bulk shear of around 20-30 knots shows that these storms may have some structure to them, lasting longer than what we would have normally seen. Additionally, with some drying above around 600 mb, could see some substantial DCAPE associated with these storms, resulting in gusty winds possibly exceeding 40 mph.

LONG TERM.../Thursday through Saturday/...Another area of low pressure moves from near Kodiak Island into the central gulf. This low will bring more steady rain back to the panhandle, mainly focused on southern areas. Currently no significant rain totals are anticipated with largest 24 hour amounts around 1 to 1.5 inches. There is a low chance, 10 to 15%, that up to 2 inches could fall around the Annette Island area in 24 hours. Areas north of Frederick Sound will see a lot lower of rain totals with near or below 0.4 inches. Around this time, late Thursday into Friday, there is a chance that Skagway and Haines also sees a period of moderate rain showers from a low over the BC area. The low in the gulf will then continue to move SE and weaken eventually moving south of the panhandle Friday. Periods of light showers will then continue late Friday into Saturday. There is a chance for a few drier breaks on Saturday, but confidence still remains low as there is little agreement on the location of the ridge. On another note, temperatures start to fall more in line with what we would typically see for this time of year with high temperatures in the low to mid 60s across the area.

AVIATION...00z TAFs...Breezy conditions have kept CIGs mostly AoA 1500 ft for most of the panhandle, with many locations reporting VFR conditions. As the front winds down and winds begin to decrease, expecting to see these CIGs begin to drop down to low MVFR to IFR conditions, particularly on south to southwest slopes. Primarily Icy Strait and southward are expected to be affected by these conditions, with Yakutat, Skagway, and Haines mostly VFR to high MVFR. Come early Tuesday, the secondary frontal wrap of this system for the southern panhandle looks significantly more convective, with possible thunderstorms. With at least some daytime heating from a dry slot before the convective showers, could see some erratic wind gusts and tall towers over PoW Island and over to Rev and Annette Island.

MARINE... Outside (Gulf and Coastal Waters): A low pressure system is currently situated in the eastern gulf, headed towards the western coast of Prince of Wales Island before it is expected to stall out. A secondary frontal system will wrap around this low pressure system going into Tuesday, once again increasing southeasterlies to 20-25 knots with waveheights as 8 ft. This front looks significantly more convective in nature, which may result in gusty winds and thunderstorms, primarily impacting areas to the south of Cape Edgecombe.

Inside (Inner Channels): The height of the stronger winds have passed, with a general downward trend in the inner channels through the evening. The secondary wrap of the low pressure system moving near the western coast of PoW Island is then expected to increase winds up to 20 knots in Clarence Strait. Furthermore, thunderstorms are a possibility in Clarence Strait, Sumner Strait, and the southern portion of Chatham Strait, at around 20% chance of occurrence. There is some evidence that storms may move northward along Chatham Strait and Stephens Passage towards the Icy Strait area, but confidence is diminishing for this outcome. Will definitely depend on how the low near PoW Island will behave and how much sun will break through the clouds. Any thunderstorms that will develop may have gusty winds up to 35 knots.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-644-661>664-671-672.