While we were celebrating our Independence Day on July 4th, Summit Station in Greenland may have experienced the coldest July temperature ever recorded in the Northern Hemisphere at -33°C (-27.4°F).   Much of Greenland has been colder-than-normal for the year so far and has had record or near record levels of accumulated snow and ice since the fall of last year.

Top: The total daily contribution to the surface mass balance from the entire ice sheet (blue line, Gt/day). Bottom: The accumulated surface mass balance from September 1st to now (blue line, Gt) and the season 2011-12 (red) which had very high summer melt in Greenland. For comparison, the mean curve from the period 1981-2010 is shown (dark grey). The same calendar day in each of the 30 years (in the period 1981-2010) will have its own value. These differences from year to year are illustrated by the light grey band. For each calendar day, however, the lowest and highest values of the 30 years have been left out. Courtesy Danish Meteorological Institute

The first week of this month was especially brutal in Greenland resulting in the record low July temperature and it also contributed to an uptick in snow and ice extent – despite the fact that it is now well into their summer season.

Discussion
Summit Station (also known as Summit Camp) is a high-altitude (10,551 feet) year-round research station in central Greenland and its exact coordinates actually can change since the ice sheet underneath is often on the move. Typical daily maximum temperatures at Summit Station are around -35°C (-31°F) in winter (January) and -10°C (14°F) in summer (July).  The record low temperature of -33°C (-27.4°F) on July 4th was more typical of the daily maximum temperature expected during the winter month of January.  [Source of information on July low temperature record at Summit Station, Greenland].

The accumulated snow and ice on Greenland has actually run at record or near record levels throughout this year and this well above normal trend began during the fall season of 2016.  In recent days, there was a sharp uptick in snow and ice associated with the brutal cold air mass (indicated by arrow on top portion of plot).  It was just five years ago in 2012 (red line on bottom portion of plot) when Greenland experienced unprecedented melting of snow and ice as revealed by satellite imagery.  Should this trend with near record or record accumulated snow and ice in Greenland continue into the upcoming winter season, it could play an important role in our weather here in the Mid-Atlantic region and potentially improve prospects for snow as Greenland can be an important source of cold air.

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