Stormy weather. It’s been a familiar tune the last couple of months at McMurdo Station, where more than 62 inches of snow fell in August.
The storms in August produced 22 days when the station was under condition 1 or 2.
There are three classes of weather under which McMurdo Station operates. Condition 3 represents mild weather in Antarctic terms. Condition 2 is activated when the weather really starts to deteriorate. In that case, winds speeds are clocked at 48 to 55 knots (55 to 63 miles per hour), wind-chill temperatures have dropped to minus 75 to minus 100 degrees Fahrenheit, and/or visibility is less than one-quarter mile.
Condition 1 represents the worst weather conditions, and can involve wind speeds greater than about 55 knots (63 mph), wind chills colder than minus 100F or visibility of less than 100 feet. During the August storms, condition 1 mainly existed on the nearby ice shelf, where the station has its aircraft operations facilities.
In fact, one storm, packing condition 1 winds, slammed into McMurdo around late August, delaying the first flights to the U.S. Antarctic Program’s largest research base by four days.[See previous article — Safe landings: Five flights arrive at McMurdo Station in August to prepare USAP for 2014-15 season.]
On Aug. 18, the station broke a daily record for maximum snowfall when eight inches fell on that day. Another record amount may have fallen on Aug. 20. However, sustained winds clocked at 58 knots (67 mph) – with gusts of up to 69 knots (79 mph) – prevented weather observers from accessing a snow catcher on the roof of a building for more than 42 hours.
Total snowfall during the 42-hour period was 18.5 inches.
No wind records were broken on Aug. 20, but there were plenty of windy days during the month. There were a couple of days when the maximum sustained winds were over 40 knots (46 mph) with max gusts in the 50s for three days. There were eleven days in August when maximum winds hit 30 knots (35 mph) with gusts of 40 knots (46 mph).
There was a total of 21 days of blowing snow and 28 days with some form of precipitation, either ice crystals or snow, during the month of August.
Source:: Antarctic Sun Featured Articles