textproduct: Juneau

UPDATE...Update for the 06Z TAF issuance

Only minor edits to the forecast this evening as it remains on track. The front is lifting north across the panhandle this evening, with snow on the leading edge eventually transitioning to rain. The rain/snow line has already lifted north of Klawock, Ketchikan and Metlakatla, slightly faster than expected. The rain/snow line will continue to lift north through the night and into the morning hours, likely pushing north of the Icy Strait corridor by early Friday afternoon.

HYDROLOGY

An atmospheric river with IVT values exceeding 500 kg/ms is inbound for the panhandle and is moving into the Southern Panhandle at time of writing. For the northern panhandle, current forecast rainfall amounts are around 1 to 1.5 inches, with locally higher amounts approaching 3 inches at higher terrain. This rainfall in combination with rapidly rising freezing levels around 2000 to 3000ft by Friday afternoon into the weekend. This rainfall in combination with rapidly rising freezing levels around 2000 to 3000ft through Friday afternoon will lead to localized flooding concerns like ponding on road ways and poor drainage due to snow blocking drains along and north of the Icy Strait Corridor, including but not limited to Juneau, Gustavus, Hoonah, Yakutat, Haines, and Skagway.

For the central and southern panhandle, current forecast rainfall amounts are around 2 to 4.5 inches, with locally higher amounts approaching 6 inches at higher terrain. A large portion of this rainfall looks to occur during the secondary shortwave moving into the southern panhandle Friday evening. This rainfall in combination with rapidly rising freezing levels around 3000 to 5000ft will lead to localized flooding concerns like rapid river rises on small streams, ponding on road ways and poor drainage due to snow blocking drains along and south of a line from Sitka to Angoon to Petersburg. ARIs for 24 hour are currently around the 4-8 year return intervals near Ketchikan, Metlakatla and south, with strongest rates coinciding with the strongest winds. While this may not immediately be an issue, as more heavy rain moves into the area, the risk for isolated landslides in steep terrain going into the evening timeframe. The decreased threat for this is diminished in the overnight hours and winds relax and rain rates slow down.

For all of the panhandle, any existing snowpack will become more dense and hard to move by Friday. Additionally, hard pack snow on driveways, parking lots, and sidewalks will become very icy. Preparations should begin for an expected rain on snow event going into the weekend. Stay tuned for further forecast updates on this system moving through the week.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Winter Storm Warning from 6 AM Friday to 9 AM AKST Saturday for AKZ318-319. Flood Watch from late Friday night through Saturday evening for AKZ318-319. Winter Weather Advisory until 9 AM AKST Friday for AKZ320. Flood Watch from Friday morning through Saturday evening for AKZ320>332. Winter Weather Advisory until 9 AM AKST Friday for AKZ321-322- 325. Strong Wind from Friday morning through Friday afternoon for AKZ328-330-332. Strong Wind late Friday night for AKZ328-330-332. High Wind Warning from 3 PM to 9 PM AKST Friday for AKZ328. High Wind Warning from 3 PM Friday to 3 AM AKST Saturday for AKZ330-332. MARINE...Storm Warning for PKZ036. Gale Warning for PKZ031-034-641>644-651-652-661>664-671-672. Small Craft Advisory for PKZ013-021-022-032-033-035-053.