Marine Weather and Tide Forecast for Kasaan, AK

PREV DISCUSSION
ISSUED AT 415 PM AKST Mon Dec 8...

SHORT TERM...Currently looking at the strong system that moved into the southern panhandle making its exit into British Columbia, leaving residual onshore flow and soon to be lighter snow for the Petersburg and Wrangell areas. With its exit, the southern panhandle is looking at a resurgence of northerly winds and colder temperatures. These northerly winds will be key in bringing stable air into Prince of Wales, Ketchikan, and Annette Island. At this time, currently expecting the arctic winds to reach south of Annette Island, but the big question on this forecasters mind is how strong and stable the dry air will be. Current thoughts is fairly strong, as ridging aloft in British Columbia look to build in high pressure, which looks to help bring down the cold air via katabatic winds.

Tuesday sees the new shortwave moves along the southwesterly flow, generating a new surface low. A similar setup to today, a band of heavy precipitation is expected to setup over Ketchikan, Annette Island, and Prince of Wales Island. Currently, only expecting eastern PoW to stay snow, as the northerly flow through tomorrow night is expected to keep cool temperatures in place. Ketchikan and Metlakatla is the most uncertain, particularly in areas exposed to southeasterly winds. If the cold, stable air from the northeast indeed is strong enough, then the warm southeasterlies are expected to decouple and lift, driving much of the stronger rates. Downtown Ketchikan is mostly sheltered from northeasterly winds, and is therefore the most likely to transition over to a rain/snow mix or primary rain. South Tongass and North Tongass, however, are more exposed to northeasterly winds, and therefore are expected to stay snow longer. Similar story to the Ferry terminal on the northern side of Metlakatla, which is exposed to the northeast narrow channel.

LONG TERM
/Wednesday through Sunday/
Very little changes made in the long term forecast as the arctic boundary that pushed down into the panhandle over the weekend continues to march southward through midweek. Wednesday a quick moving low will finish dropping snow in the southern panhandle before moving inland over British Columbia and ushering in a cold dry second half of the week. Building high pressure in NW Canada and interior Alaska supported by a deep arctic trough in the upper levels is creating offshore flow and ushering colder continental air through the northern panhandle. This air is very cold with 850 mb temps plummeting into the -15 to -25 C range by mid week across the northern panhandle and near -10 C over the south. At sea level this will translate to overnight lows ranging from single digits above or below zero for the north to teens and 20s for the south.

Daytime highs will struggle to reach the 20s for the north and into the 30s for the south as we progress through the week. Coldest temperatures look to occur Monday night through Wednesday night, but sub freezing temperatures are likely to stick around into next weekend. The panhandle from Icy Strait northward will be watched as many locations will approach their criteria for cold weather advisories or extreme cold warnings (especially the Haines and Klondike Highways) through at least mid week. As of this forecast discussion, an extreme cold warning for Skagway, primarily along the Klondike Highway, was extended through noon Wednesday for extremely cold temperatures as low as 45 degrees below.

Strong outflow winds of at least gale force will be blowing along many northern panhandle channels through most of the week. A strong 1035 mb high in the Yukon is the main driver of this outflow and it will persist and strengthen to 1050 mb by late week. Expect gusty winds out of many of the outflow areas in the northern panhandle to start with, but expect outflow out of areas farther south through the week as the Yukon high spreads into northern British Columbia by late week. Gaps along the NE gulf coast will serve as outlets for strong winds as well through the period. Aside from the above mentioned hazardously cold temperatures, freezing spray will become a more widespread problem for many marine areas in the inner channels and along the NE gulf coast. The freezing spray could become heavy at times in Lynn Canal, near Taku Inlet, and northern parts of Glacier Bay throughout the week.

The continuing outflow will also keep most of the panhandle dry through the mid and long range except for possibly the far south.
There is the possibility of a another snow event for the south next weekend that is highly dependent upon an upper level ridge moving over the panhandle at the start of the weekend followed by another arctic trough replacing the one that dominates the state for most of the week. One thing is for certain, winter has come to southeast Alaska.

AVIATION
/through Tuesday evening/
Flying conditions continue to improve this evening as the heavy band of snow that was set up earlier across the central panhandle has diminished. VIS across the Petersburg and Kake areas have been improving while the snow has stopped in most other locations. Along with improving VIS, CIGs have improved to VFR for some locations across the southern panhandle while MVFR does remain very prevalent. Across the northern half of the panhandle, VFR conditions remain but some areas continue to experience strong outflow winds as well as some LLWS from these winds, particularly Juneau and Yakutat. Conditions for the southern panhandle are expected to deteriorate later this evening as the next wave of snow will move in during the early morning hours reinforcing MVFR conditions or potentially dropping conditions to IFR with some LIFR conditions possible. Turbulence and icing continue to be a concern from the AAWU especially for icing across the southern panhandle while turbulence is possible for the entire panhandle

MARINE...
Outside: Strong outflow winds continue to dominate the eastern gulf coastal waters through Tuesday. Gale to storm force winds with strong storm force gusts are blowing out of interior passes, as well as any available drainage channel. Only a minor reduction in strength is expected through Thursday, but winds are overall expected to stay elevated through the week. Wave heights are around 7 to 10 ft through the majority of the gulf, with areas affected by the outflow winds seeing up to 15 ft waves persist through the week. Freezing spray is possible with strong wind gusts, mostly along the coastal waters. The central gulf is more calm, only experiencing disorganized moderate breezes as the low in the western gulf dissipates.

Inside: Strong gale to storm force outflow winds have persisted through Monday and are expected to continue through the week. A very strong pressure gradient in the northern panhandle is forcing northerly storm force winds with gusts in the 60 kt range down through Lynn Canal and Stephens Passage, as well as strong gale force winds with storm force gusts out of Taku Inlet and through the rest of the inner channels. Wave heights between 8 to 10 ft are expected in areas of the strongest winds, with the rest of the channels seeing around 6 ft or less and diminishing overnight.
Channel entrances may see up to 15 ft waves at their peak. The pressure gradient is expected to only slightly relax overnight, continuing gale force outflow winds in Lynn Canal and Stephens passage and strong breezes to near gale force winds for the rest of the channels through the week.

AJK WATCHES/WARNINGS/ADVISORIES
PUBLIC...Strong Wind until 9 PM AKST this evening for AKZ318.
Extreme Cold Warning until noon AKST Wednesday for AKZ318.
Cold Weather Advisory until 3 PM AKST Wednesday for AKZ319.
Cold Weather Advisory from midnight tonight to noon AKST Tuesday for AKZ320-325.
Strong Wind until 6 AM AKST Tuesday for AKZ325.
Winter Storm Warning until 9 PM AKST this evening for AKZ326-329- 331.
Winter Storm Warning from 9 AM Tuesday to midnight AKST Tuesday night for AKZ328-330-332.
Winter Weather Advisory from 9 AM Tuesday to 3 AM AKST Wednesday for AKZ331.
MARINE...Heavy Freezing Spray Warning for PKZ011>013-031.
Heavy Freezing Spray Warning for PKZ021.
Heavy Freezing Spray Warning for PKZ021.
Heavy Freezing Spray Warning for PKZ032.
Storm Warning for PKZ012-013-651.
Gale Warning for PKZ011-022-031>034-053-643-644-663-664-671.
Small Craft Advisory for PKZ021-035-036-641-642-652-661-662-672.