textproduct: Juneau

UPDATE.../to add the 06z aviation discussion/

SYNOPSIS

Key Messages:

-Brief break for Monday before another stronger storm force system moves in for Tuesday.

-Moderate to heavy rainfall, along with strong winds, are expected over most of SEAK on Tuesday and Tuesday night.

-Significant increase in seas for the eastern Gulf of Alaska and coastal panhandle with the fast moving system Tuesday.

LONG TERM

For the start of the long term period, the low affecting the panhandle will continue to work inland into the Yukon and Interior Alaska. With this low working inland, there is an expected jump in the winds through the Inner channels. With this, some areas could see some strong winds behind the low before onshore flow returns to the area. With the onshore flow, precipitation is expected to continue for most of the panhandle keeping the wet weather going. Most of the precipitation with this onshore flow is expected to remain on the lighter side compared to what we have been seeing previously. Heading into the latter half of the week, high pressure is expected to become the more dominant pattern for the SE area. With this high pressure, temperatures should become fairly stable but we could also see the development of fog across the panhandle. The likelihood of this is greater for the southern panhandle but could be possible farther north too. The one exception to this will be for the Yakutat area and farther to the west of Yakutat Bay where an atmospheric river is expected to impact the area over towards Prince William Sound and portions of the Anchorage Forecast Office CWA. For the Yakutat area, 24 hour precipitation could jump up to 2- 2.5" of precipitation by Friday. As we head into the weekend, conditions look to be fairly quiet for the area, even more so when compared to the weather that SE has experienced over the past month. CPC guidance for the 6 to 10 day and 8 to 14 day outlook show SE AK moving towards a near normal for temperatures and below normal for precipitation.

AVIATION.../Until 06Z Wednesday/

A very potent frontal system begins its push northward through the panhandle Tuesday morning & continues to do so through the end of the 24-hour TAF period & beyond. Southeasterly winds increase & become gusty through the period as the front progresses northward. The highest winds will be for the southern panhandle & outer coast regions for the TAF period. Beyond the TAF timeframe, the highest winds will make their way through the northern third of the panhandle. Centered between 1.5 & 2 kft, southeasterly to southerly LLWS up to around 55-60 kt with the highest values toward the southern panhandle & outer coast are anticipates, increasing as we progress through the TAF period. FLight conditions will generally remain in the MVFR/IFR category range everywhere through the period.

MARINE

Inside Channels: There will be a surge of 20 to 25 kt southerlies Monday night that will move from S to N up the panhandle as a pre- frontal wave moves through the area. Seas mainly driven by wind wave though seas near ocean entrances with southerly exposure are noticeably higher due to high S swell in the gulf.

As the next system moves in from the south into Tuesday morning, gale force winds will push into Clarence and southern Chatham becoming storm force by Tuesday night. The front will push northward following behind the first wave, bringing gale force winds to strong gales northward across the rest of the inner channels into Wednesday morning. Storm force winds will impact parts of Cross Sound, Stephens Passage, and Lynn Canal as the front pushes through to the north with a strong surge of southerly winds, with the highest winds in channels exposed to southerly flow and parts of the channels that may see some convergence, such as around Point Arden as well as into northern Lynn Canal near Eldred Rock as the wind funnels into the northern channels. Gusts as the main front moves through are likely to reach above 60 kt. Seas will begin to build Tuesday into Tuesday night from S to N to between 6 and 10 ft at the highest.

Outside waters: Winds start ramping up again into Tuesday as a storm force low moves in from the north pacific. Storm force winds expected to move rather quickly up the coastline from S to N as the low travels northward, reaching the northern coast by Tuesday night before wind speeds begin to diminish slightly into Wednesday. The highest speeds are expected right along the outer coastline to the east of the low, with near gales up to strong gales further west offshore. As the front passes, the winds will shift from a southerly to SE-ly direction to a SW-ly direction as onshore flow follows the system as it moves inland by Wednesday. Seas tonight remain between 10 and 12 ft, before building from S to N beginning with the waters off of PoW and near Haida Gwaii. Seas will build to 25 to 32 ft along the coast as the low moves northward Tuesday into late Tuesday night, before beginning to subside into Wednesday. This is mostly being driven by a 25 to 30 ft S swell with a period of around 15 sec.

HYDROLOGY

Another fast moving and wet system is expected for Tuesday into Tuesday night, bringing more moderate to heavy rain and strong winds. Total rainfall amounts will be around 1 to 3 inches over the central and southern panhandle, with gusty winds up to 65 mph possible during the event. The heaviest rainfall rates will occur during the morning and afternoon hours, tapering off during the evening hours. Strongest wind gusts will follow the heaviest rain, occurring during the late afternoon into the evening hours, then tapering off overnight. Additionally, freezing levels will be rising to 4000 to 6000 ft on Tuesday, leading to additional snowmelt. Expect rapid rises on smaller area rivers and streams Tuesday into Tuesday night, but we are not expecting flooding at this time. Winds and rain will continue to diminish through the day Wednesday.

Additionally, moderate to heavy rains will reach the northern panhandle by late Tueday morning and continuing through Tuesday night. Total rainfall amounts will be around 1.5 to 3.5 inches with gusty winds up to 65 mph possible during the event. The heaviest rainfall rates will occur during the afternoon and evening hours, tapering off during the overnight hours. Strongest wind gusts will follow the heaviest rain, occurring during the evening and overnight hours, then tapering off Wednesday morning. Freezing levels will be rising to 2000 to 5000 ft. Any areas that are continuing to see drainage issues or ponding will likely see additional pooling of water. Winds and rain will continue to diminish through the day Wednesday.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...High Wind Warning from 9 PM Tuesday to 9 PM AKST Wednesday for AKZ317>319. Winter Storm Warning from noon Tuesday to 9 AM AKST Wednesday for AKZ318. High Wind Warning from 6 PM Tuesday to 9 AM AKST Wednesday for AKZ320>322-324-325. High Wind Warning from noon Tuesday to 6 AM AKST Wednesday for AKZ323-326>330-332. MARINE...Storm Warning for PKZ012-013-022-031-033-036-641>644-651-661>664- 671. Gale Warning for PKZ011-021-032-034-035-053-652-672.