Sitka Nature

The the last couple of weeks have seen quite a bit of stormy weather around Sitka. Saturday had the highest winds of the fall storm season so far with sustained winds over 30mph and gusts up to near 60mph.

Winds were out of the West-Southwest, pushing the waves through Middle Channel to crash against the south end of the runway. While on a brief walk Saturday morning, I could see the waves splashing up above the level of the runway, and I heard later that at least one flight was canceled due to boulders which had been thrown up on the runway.

This past week 2 or 3 low pressure centers merged in the eastern Gulf of Alaska to create an exceptionally strong low pressure system. Strong low pressure systems are typically associated with strong winds, big waves, and storm surge that leads to higher tides. Accordingly, Sitka was under a Wind Advisory from the National Weather Service that lasted from early Wednesday morning through Friday morning. Marine forecasts called for seas to 34 feet (which probably contributed to the surf in coastal Washington).

Coincidentally, the high tide predicted for Thursday afternoon was one of the higher ones of the year at 11.6 feet (for context, the very highest predicted tide of the year tends to be between 12.7 and 13 feet, depending on the year, and much of the year tides don’t get above 11 feet). Based on my subjective impression of the water height at Crescent Harbor (see photo above), I thought it was easily above 12 feet, and maybe pushing closer to 13 feet. Later, I was able to find the coastal water level monitoring data from NOAA and saw that the observed water level was nearly 13.4 ft, almost 1.4 feet above the predicted level.

The highest water level I remember seeing was during the 1984 Thanksgiving Day storm. I remember driving out the road with my parents and brother to look at the ocean near the time of the predicted high tide. Waves were pushing rocks up on the parking lot at Sandy Beach, Nelson Logging Road was well under water, and the waves were splashing up underneath the furthest-out trailer at Arrowhead Trailer Court (subsequently fill and a rip-rap wall was added to protect the trailers). On a subsequent hunting trip, I saw debris that had obviously been deposited by a high tide up in the woods several feet off the beach.

I was able to find historical information on the Sitka Station page of the NOAA Tides & Currents site. The predicted tide for that day was about 12.3 feet, but the maximum reported observation was nearly 14.6 feet. A higher predicted tide and greater storm associated increase made that tide much more significant than the one this past week which was unusually high, but not hugely so.

Sunlight on St. Lazaria Island on an early June evening.

I was reminded of a trip out to St. Lazaria earlier this month when I ran into someone I know who is spending the summer out there working for the Fish and Wildlife Service monitoring seabird populations. St. Lazaria is part of the Alaska Maritime National Wildlife Refuge and is home to hundreds of thousands of breeding birds, mostly storm-petrels and alcids.

I was interested to find out that most of the alcids have only just begun nesting, though the Fork-tailed Storm-petrels are much further along, with some chicks already present in the burrow nests. The Glaucous-winged Gulls also had chicks, but it sounds like many of them may have perished in an unusually strong storm for this time of year. The waves were crashing up on the outer cliffs, and even wrapping around the west end of the island and battering the usually well protected cove, totalling the skiff used by the FWS scientists and moving the anchor around to the east side of the island in the process. Carrie said she thought the waves were probably 18 feet high, splashing well up the cliff. The sound of the waves was impressive, creating a feeling like the cabin was shaking, despite not being directly exposed to the waves. Hearing about this storm reminded me of my desire to get out to a remote stretch of the outer coast before a large storm rolls in and watch the waves pound the shoreline (from a safe distance, of course).

Waves would have been crashing well up the cliffs shown here during the storm.