HIGH SEA WINDS MAPPED FROM SPACE

The Gulf Stream is linked to causing high winds so why are our local winds often so weak?
Well we often have high winds during the winter season here in Jacksonville especially when strong high pressure ridges move off the mid Atlantic and generate local Nor’easters. The First Coast and the southeast United States in general, are located in an area of relatively lighter wind patterns. Due to the proximity of the Bermuda Ridge.

A recent climatology mapping sea winds using QuickSCAT has been completed by Takeaki Sampe and Shang-Ping Xie, highlights areas of strong winds over the globe. High winds are most likely in the North Atlantic in midwinter. The colors in this image show the percent of high winds over 45 mph. Stronger winds are red and yellow. Notice how the high winds are located off the northeast US and Canadian Maritimes. This is the location of the average mid-latitude jet stream that drives strong storms over the area. But the Gulf Stream plays a major role in increasing the high winds. It causes a gradient of warm and cold water called static instability. This contrast results in vertical turbulent mixing of the air. Gusty winds aloft dives down to the surface to replace warmer lighter air. This acceleration of the surface wind is maximized along the northern wall of the Gulf Stream where it branches east into the Atlantic current.

Local effects of the shape of land contribute to additional wind maximums south of Greenland, along the south coast of France, and west of Norway. In France it’s the gap in the Alps that funnels cold dry “mistral" winds down into the Mediterranean Sea.

Sometimes the contrast in sea surface temperatures (high static instability) results in a front on the water visibly marking the calm and white-cap conditions on the cold and warm sides. The warm side is always more rough for boaters.

Off the coast of Jacksonville the Gulf Stream is about 60 miles from the beach. It is not common to see these wind effects because we are so far off the main jet stream storm track. And tropical storms are so infrequent compared to winter storms that their contribution to the wind climatology doesn’t have a big impact.