The most recent storm seemed like a strong one, with sustained wind speeds of over 50mph on St. Lawrence Island; and the balloon sounding from Nome on Tuesday morning reported a wind speed of 49mph at ground level. However, the minimum central pressure of the storm was only about 980mb when it reached Alaska, which isn't particularly low by Bering Sea standards.
The chart below shows the typical monthly extremes in MSLP for a latitude/longitude box centered on the west coast of Alaska (depicted on the map underneath). The months of October through February all typically bring at least one storm with minimum MSLP of 975mb or lower somewhere in this region; so the latest instance was a fairly run-of-the-mill storm. What is not normal, however, is the lack of sea ice; only last year had significantly less ice on this date in the modern satellite record (but mid-February 1985 had about the same amount).
Kudos to the weather service guys/gals for getting a balloon off under such conditions. And over and over again with the series of storms they've had.ReplyDelete
Yes. Nome is supposed to be switching over to the automated launch system (autolauncher) this year, and the wind cutoff is 25 m/s (55 mph), so this limit will come into play occasionally. A bigger problem for the autolauncher program in Alaska is the temperature cutoff of -40... no more soundings when it's cold.Delete
Surely they are not going to accept that -40 cutoff for interior stations (they really should not for Nome, Kotzebue and Barrow either!)ReplyDelete
Unfortunately, from what I've heard, the temperature cutoff is a restriction that has been deemed acceptable.Delete