Open water over the ocean creates conditions that lead to hoar frost and rime ice. These conditions impact travel and are expected to become more common as ice forms later in Norton Sound.
Observation by John Henry:
With mainly open water surrounding the coastal village of Unalakleet, the ambient weather impacts yielded ice fog, frost heaves, and cancelled flights from Ravn coming from Anchorage during 12/2/19 and 12/3/19.
Rick Thoman, Climate Scientist at the Alaska Center for Climate Assessment and Policy, writes:
This is a great series of photos showing extensive hoar frost and rime ice. Hoar frost forms when air with relative humidity very close to 100% comes in contact with objects that are below freezing. Hoar frost forms delicate crystals that can grow to an inch or more in length if not disturbed. Hoar frost growths from water vapor is deposited as ice without first passing through a water phase. Most of the photos also show rime icing, which is formed when small water droplets in fog freeze on contact with surfaces that are below freezing. With ice forming later in the autumn in Norton Sound, this will become increasingly common.
Comments from LEO Editors:
Pictured below are two maps that show sea ice conditions during the month of November. These maps are generated by the National Snow & Ice Data Center (NSIDC).
The first map shows the sea ice extent. The "extent" shows whether there is ice coverage in an area or not. The pink lines on the figure show how far south the ice usually formed between 1981-2010. During November 2019, sea ice is present in Norton Sound and near the coast in part of the Chukchi Sea, but there is much more open water than normal.
The second map shows the sea ice concentration. The "concentration" represents the amount of area that is covered by ice. Areas colored with a shade of blue indicate that the area is not 100% covered in ice and that there are areas of open water. Near Unalakleet, we can see that although there is ice present, there is open water in Norton Sound.
For more information on sea ice terminology, see the NSIDC "All About Ice" terminology glossary. Erica Lujan
Frost