textproduct: Juneau

AVIATION

VFR conditions ongoing across the panhandle this morning with ceilings AoA 3500ft and visbys generally greater than 6SM, however a strong low continues to spin off shore in the Gulf with its attendant front and moderate to heavy rainfall pushing inland. Conditions will continue to deteriorate through the afternoon to general MVFR to low-end VFR as this low tracks NW towards Anchorage. Main impact for our area will be the strong surface wind gusts 30 to 40kts and LLWS up to 50kts across the coastal terminals from Yakutat southward to Klawock, and over to Ketchikan through the evening. For the Icy Strait terminals, Gustavus and Juneau, thinking periods of stronger gusts up to 30 kts will continue through the evening. Winds will gradually diminish through 03z to 06z this evening for terminals other than Yakutat as the low pushes NW, holding on at Yakutat through 12z.

By 09z tomorrow morning, another low, although small, pushes into the southern panhandle, so expecting a brief lull followed by yet another round of strong wind gusts for Klawock and Ketchikan with gusts up to 30 to 35s from 09z through 18z Tuesday morning.

SYNOPSIS

Key Messages:

- A Strong storm force low pressure system enters the Gulf Monday bringing rain and high winds.

- High Wind Warning for Prince of Wales Island remains in effect through Monday evening with wind gusts up to 60 mph expected. Wind Advisories along the coast and southern panhandle continue through the day with expected wind gusts of 40 to 55 mph.

- Winter Storm Warning continues through Monday evening for the Haines Highway near Haines Customs, with snowfall totals of 8 to 12 inches.

- Another low moves out of the Pacific and into the southern panhandle by Tuesday morning into the afternoon, bringing another potential round of strong wind gusts to Prince of Wales, Ketchikan, and Annette Island.

LONG TERM

Thursday morning sees the beginning of a stronger atmospheric river move into the area. Some rather impressive dynamics look to be associated with this storm, with strong initial warm air advection, and relatively cold air advecting eastward. These ingredients coupled with sea surface temperatures still around the mid 50s means that the environment leans more towards the convective. Furthermore, a strong jet aloft with plenty of divergence behind the warm front sets the stage for meso vertices forming along the front. These cause a number of issues: timing, location, and intensity of rainfall and highest winds can shift drastically. Individual model runs tend to struggle with these environments, with run to run consistency of both the GFS and EC inconclusive on individual features. Ensemble guidance provides a clue on the location of highest wind speeds and rainfall however. At this point, the southern half of the panhandle has the highest likelihood of longer duration, heavier rainfall. The specifics regarding the hydrology portion of this storm are noted in the hydrology section.

Looking towards the weekend, there is roughly a 60-40 split of active weather continuing and a stronger low passing south respectively. If active weather continues, then generally southerly winds will accompany mostly rain for the panhandle. For the low passing south, this would invite stronger, downsloping northerlies, which would dry out the panhandle and bring cooler temperatures overnight.

MARINE

Outer waters:

The low pressure system sitting in the northern gulf is swinging across yet another frontal system, generating 25-30 knot southerlies in the gulf waters through tonight. A shift to the southwest with similar wind speeds is expected during the early morning hours for the coastal zones before diminishing through Saturday night. Wave heights associated with the southwesterlies are expected to build to around 15 ft offshore between Cape Spencer and Cape Edgecombe. May also see some convective cells with some lightning strikes and stronger wind gusts. The low pressure, then vertically stacked, should slowly fill and move southeast, keeping up to 20 knot westerlies for Sunday morning before diminishing.

Inside Waters:

Leading into the front, building high pressure in the southern panhandle in wake of the stronger front that moved through the southern portion of Clarence Strait may decouple winds. This combined with clearing skies and abundant moisture from recent showers may generate some fog overnight tonight ahead of the incoming front. The front from the aforementioned low pressure in the central gulf is expected to bring up southeast winds early Saturday morning to around 20-25 knots. Highest wind speeds, and associated small craft advisories, look to be for Lynn Canal and Stephens Passage. Definitely possibly to see an upgrade to 25 knot winds for northern Chatham Strait, but did not have the confidence for this forecast package.

AJK WATCHES/WARNINGS/ADVISORIES

PUBLIC...Wind Advisory from 3 PM this afternoon to 5 AM AKST Tuesday for AKZ317. Winter Storm Warning until 6 PM AKST this evening for AKZ319. Wind Advisory until 9 PM AKST this evening for AKZ323. Wind Advisory until 6 PM AKST this evening for AKZ327-330-332. High Wind Warning until 3 PM AKST this afternoon for AKZ328. MARINE...Storm Warning for PKZ641>644-651-652-661>664-671-672. Gale Warning for PKZ021-022-032-033-035-036-053. Small Craft Advisory for PKZ011-013-031-034.