textproduct: Juneau

UPDATE

Update to the Aviation Section to include the 06z set of TAFs.

PREV DISCUSSION......ISSUED AT 735 PM AKDT Mon May 18

SYNOPSIS...

Key Messages:

- A weak system brings some rain to the northern coast tonight into Tuesday, with winds and seas decreasing into Tuesday morning.

- Wednesday morning a gale force front impacts the region.

SHORT TERM...Tonight through Wednesday/ A front passed this morning with westerly winds behind it an some breaks in the clouds showing up through the afternoon. There are some showers still around and expect most along west facing slopes while the lee side will see the best breaks this evening. A band of vorticity looks to track over the region tonight, so have kept scattered shower potential in the forecast for that, namely across the north. There is also CAA behind this front, so expecting a chilly night, some places that clear out more across the north could see temps into the mid 30s, getting close to frost potential, but kept it just above that due to the amount of clouds around.

Upper level ridging sharpens some for Tuesday with NWLY flow, so more breaks are in the works, especially for the southern inner channels (Ketchikan). Isolated showers will remain around the northern mountains with best breaks over the inner channels. Some sunshine will make it feel markedly warmer than the last couple days and made a point to have Tuesday be warmer than Monday or Wednesday.

The next front will be on our doorstep Tuesday night. Yakutat can expect rain before dawn and winds will back around to the S-SE ahead of the front. Rain will spread across the panhandle through day, becoming heavy at times along the northern/central outer coast in the morning and afternoon. Rain will take until late afternoon to reach as far east as Hyder. Looking at frontal passage with a wind shift to the west again late Wednesday night.

LONG TERM.../ Thursday to Monday / Thursday will likely be showers or fading shower activity in a post weather front (Wednesday's) situation. The associated low feature near Prince William Sound weakens and will be getting absorbed during Thursday/Thursday night into the front from a low over Bristol Bay. The new front sweeps the western gulf Thursday and to the eastern Gulf of Alaska Thursday night. Yakutat should Good rain rates Thursday night. The front is forecast to be weakening, as the feature moves way from the parent low which stayed over Bristol Bay so the feature that rolls across the panhandle Friday is a frontal band followed by a ridge over the gulf to the panhandle for the start of the weekend.

For the Memorial Day Weekend / Saturday to Monday / The models here are still trying to settle into a pattern. Indications are that a system will spin into the Gulf of Alaska, mainly for Sunday, however its intensity and track are uncertain at this point. Ensemble means and a variety of operational models are trending toward a 995 to 1000 mb low heading in the general direction of Dixon Entrance by Sunday night, but there are indications the low could be as strong as 985 mb, and some outliers are pointing toward a much further south track and weaker low. Overall the weekend may be cool and damp or could be wet and windy, especially over the southern panhandle on Sunday depending on how this system evolves.

AVIATION...Mostly VFR conditions continue this evening with some isolated pockets of ceilings dropping down to MVFR. Some areas could see ceilings decrease from VFR down to MVFR this evening while other locations such as Skagway could see more clearing during the overnight hours. One concern with the potential for clearing would be fog development across the panhandle. Some of the TAFs reflect this potential with some reduced visibilities or fog in the vicinity. But places with less confidence were not included but will still need to be watched for any development during the overnight hours. Heading into the middle of the day tomorrow, conditions should generally remain the same throughout the day with the exception of the NE Gulf coast which will likely rain return before other locations which will keep conditions lower.

MARINE... Winds continue to diminish in the wake of a front which moved through on Sunday, although respectable southerly flow will persist in Northern Lynn Canal through the foreseeable future. A system moving across the Gulf on Tuesday arrives in SE AK on Wednesday, bringing gale force winds to the N and NE Gulf Coast, and small craft conditions to the inner channels.

Outside coastal waters: Winds have diminished substantially in the wake of the last system, and seas will be following suit Monday evening, with seas trending down to 6 to 7 ft for most areas with the exception of the N Gulf East of Yakutat Bay. WInds trend upwards on Tuesday across the Gulf, and by Tuesday night for the outer coast, as another system approaches SE AK. Expect gale force winds to be largely focused around the northern gulf and gulf coast, down as far as Cape Fairweather. Waveheights ramp back up as this system moves in, reaching 12-15 ft on Wednesday. Winds and waveheights then diminish late Wednesday into Thursday as the system departs.

Inside Channels: Winds diminish across the inner channels through Monday evening, with the exception of Lynn Canal, where elevated flow of ~20 kt persists. Winds will ramp back up to 10-15 kt on Tuesday, as southerly flow is sustained by a weak wave moving onshore. Wednesday will see widespread sustained southerly winds of 25 to 30 kt as a strong warm front moves onshore, alongside elevated seas, with ocean entrances reaching 10+ feet, and areas where swell reaches seeing additional inclement conditions.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...None. MARINE...Small Craft Advisory for PKZ641-651-652-661>663-672.