Marine Weather and Tide Forecast for Sitka and, AK

SHORT TERM
The upper level low currently west of Prince of Wales Island continues to slowly drift southwestward. The surface low moving south of Haida Gwaii. The bigger story continues to be multiple shortwave moves from southeast to northwest over the northern half of the panhandle and NE gulf coast. The primary wave looks to exit our CWA this afternoon, with the secondary wave expected to primarily impact the NE gulf coast later this afternoon and this evening. Daytime heating from some clearing behind the front exiting this afternoon along with higher than normal dewpoints and plenty of vorticity advection and cold temperatures are expected to spark more isolated thunderstorms. Expecting these storms to be largely over the Coast Mountains to the west of Icy Bay.

For tonight, it is possible to get some clearing from easterly downsloping winds from the upper level low. Confidence is relatively low for this scenario, as existing vorticity advection may help lift clouds or mix them out entirely. Kept the inherited forecast, as there is still plenty of moisture available along with lighter winds.

Going into Friday, the surface ridge in the GoA is expected to strengthen once again, promoting NWerly winds, some clearing, and warmer temperatures across the panhandle. 850 mb temperatures are still somewhat below normal to right around normal, even with plenty of solar heating. This indicates that temperatures are not going to be significantly above normal, nor are temperatures expected to exceed 80 degrees. The one exception would be within around 10 miles of the Canadian border on the Haines and Klondike Highway. Just given the low 850s; however, did not issue any heat advisories this time around. Additionally for Friday, easterly winds look to continue, with a developing low in British Columbia likely to spark up rain showers and thunderstorms. Easterly flow becoming divergent over Misty Fjords with plenty of daytime heating has the potential to have thunderstorms move over into the aforementioned area.
Chances at this point are around 20%, or isolated.

LONG TERM
/Sunday through Wednesday/...The long term forecast continues to be relatively benign through the weekend, with shower chances building back in Sunday into early next week for the northern inner channels. Ridging over the gulf continues to build through the weekend, increasing gulf winds to a northwesterly fresh to strong breeze down the coast through the rest of the extended period and tapering off through Tuesday. The panhandle looks to stay dry Saturday, which will allow for widespread mostly sunny skies, increased daytime high temperatures, and developing sea breezes through midday. Shower potential will still be present through the period as flow turns more westerly and onshore, but Saturday continues to look drier and drier as it gets closer. With these clearing skies this weekend, much of the panhandle may see high temperatures reaching the high 60s and even the low 70s. 10 to 15 kt sea breezes should increase through midday for areas seeing significant clearing and subsequently warm daytime high temperatures. A tightening pressure gradient over Northern Lynn Canal looks to increase winds through Taiya Inlet and into Skagway through the early afternoon of both weekend days, which has the potential to bring winds up to 20 to 25 kts with any sea breeze influence.

The rest of the period is still relatively quiet for Southeast Alaska standards, but shower potential will increase Sunday and last through the early work week due to multiple upper level disturbances advecting across the northern gulf. An upper level shortwave trough in the northern gulf doesn't have much in terms of a surface inflection, but as the disturbance with increased vorticity pushes over the panhandle Saturday night, potential for showers increases for the northern panhandle and along the outer coast Sunday and through the rest of the period. Mid-level moisture looks to be lacking through this period, so any showers that do develop will most likely be weak and may not make it all the way inland over the panhandle. For much of the panhandle, this may just manifest as increased cloud cover or some light drizzle depending upon the formation of a marine layer. Even so, this will still decrease daytime high temperature potential to the low to mid 60s.

AVIATION
A weak low pressure system is continuing to generate MVFR to low VFR ceilings across much of the area. After 09Z tonight, light winds and breaks in sky cover may result in the formation of patchy fog for PAHN, PAJN, and PAGS. Any fog should quickly burn off by 15Z Friday. Farther south, occasional light rain and mist will be possible through much of the night with a general improving trend and prevailing VFR ceilings toward the end of the forecast period.

MARINE
Outside (Gulf and Coastal Waters): With an area of low pressure in the Gulf of Alaska, winds up to 10 kts have been observed. Friday, the low is expected to dissipate and a ridge will build-in behind it. From Friday into Sunday, this will lead to westerly winds 20-25 kts in the Southeast Gulf of Alaska and waves 5- 10 feet.

Inside (Inner Channels): Winds have been fairly light today in the inner channels. As a ridge of high pressure develops behind the trough in the Gulf of Alaska Friday, this will lead to breezy northerly winds up to 15 kts in Clarence Strait, and waves up to 4 feet. The high pressure will also lead to westerly 15-20 kt winds in Cross Sound. Overall, the strongest winds look to remain in the outer waters.



AJK WATCHES/WARNINGS/ADVISORIES
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ641-642-661>664.