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Too-many times, those who conduct damage assessments for the National Weather Service, have to defer between tornadic and straight line wind damage.  The majority of the time, thunderstorm damage turns out to be nothing more than high wind related.

You may recall my previous blog entry, in which I outlined how thunderstorm activity increased towards the the peak of the spring season.  As the atmosphere becomes more uniform in temperature throughout, storms take on different characteristics.  It's when you have colder air aloft that feeds more-intense severe weather.

As storms grow to immense proportions, colder and drier air aloft is entrained into the downdraft, promoting evaporative cooling. The contrast between the surrounding warm air creates what is known as a gradient, which accelerates wind speeds dramatically towards the surface, or just below the base of the thunderstorm.

As temperatures drop several degrees, wind speeds preceding the thunderstorm "core" can reach speeds in excess of 58-mph, which are deemed severe by National Weather Service standards.  Winds of this nature are capable of snapping tree limbs and even toppling weakened and poorly built structures.

What crews look for when assessing storm damage, is the layout of debris on the surface.  In other words, if wooden shed is leaning to the east and a wind speed of 60-mph was recorded from the west, then damage is uniform and most-likely the result of straight line winds.  However, if debris from the same structure is scattered in multiple directions, then damage maybe labeled as tornadic.

Join me next time, as I investigate some of the myths and facts about tornadoes.

JB