Changeable Fall Weather

As is symbolic of the changing seasons, wide variations in hot and cold weather (as well as wet and dry weather) are quite common in the middle latitudes.  In the Mid-Atlantic Region, such extremes are especially common during the fall months.

2014:  A severe weather outbreak occurred last week across the Midwestern and Eastern United States.  Although not as frequent as in the spring, the fall also has severe weather.  From October 12 through October 15, there were more than three dozen confirmed tornadoes; including the first October tornado fatalities in the United States since 2009.  

Two of the tornadoes touched down locally with one near Alexandria, VA and another in Howard County, MD.  They were both weak with estimated winds of 55 - 65 mph making them each an EF-0 on the Enhanced Fujita Scale.  The presence of any of the following makes a thunderstorm “severe” - wind gusts greater than 58 mph, hail at least 1” in diameter, or a tornado.  Overall, there were more than 500 reports of severe weather during the four day period last week. 

2011:  Another demonstration of the seasonal battle that occurs in the Mid-Atlantic during the fall came in 2011.  On October 13, there was a significant severe weather outbreak that included a total of 14 relatively weak tornadoes in central and northern Virginia.  Fortunately, there was no significant damage and no injuries were reported.

2009:  The second of two consecutive record low-high temperatures occurred at National Airport when the high reached only 47 degrees, after it was 45 on October 16.  This coincided with five consecutive days of rainfall for a storm total of 2.6” at National Airport and 2.26” at Dulles Airport.

2007:  Washington, D.C. experienced a record 34 consecutive days without measureable precipitation.  This dry streak ended October 19 when 0.37” fell at National Airport.  What helped keep the Mid-Atlantic so dry for so long was a strong area of high pressure that remained nearly stationary for an extended period of time which kept weather conditions generally sunny and mild.