It's Calm Now, but Don't Forget Deadly Irene and Lee

Hurricane Irene nearing the East Coast of the U.S. (Source: NOAA)

Despite the quiet nature of the 2013-2014 Atlantic hurricane seasons, it was just three years ago the Mid-Atlantic Region saw significant impacts from two tropical systems. The first was a weakening hurricane while the second was the remnants of a strong tropical storm.  On August 27 and 28, 2011, the remnants of Hurricane Irene brought the Nation’s Capital appreciable rainfall.  Two-day totals at National Airport were 3.83”, while Dulles Airport in nearby Virginia saw a storm total of 1.41”.

These rains helped replenish the local reservoirs and waterways after an extremely hot summer.  According to the National Weather Service, July 2011 was the warmest on record in the Nation’s Capital.  At peak intensity, Irene was a major Category 3 hurricane, but weakened to a Category 1 before making landfall in North Carolina.  Due to the extensive damage Irene caused, the name “Irene” was retired by the World Meteorological Organization.  Less than two weeks later, the remnants of Tropical Storm Lee came along.

During a four-day period ending September 9, 2011, the slow-moving remnants of Lee brought a total of 6.93” of rain at National Airport and 6.7” fell at Dulles Airport.  These storm totals helped make September 2011 the fifth wettest September on record in the Nation’s Capital.  To add to that, the 8.54” that fell in Baltimore during the same four-day period helped make September 2011 their wettest September on record according to NOAA.  That helps underscore how much rain tropical systems and their remnants can produce.

Segue from Summer to Fall

Meteorological fall officially began September 1 and symbolizes the point of the year when temperatures begin to cool relatively quickly.  The average high in the Nation’s Capital goes from 84 degrees on September 1 down to 74 degrees on September 30 at National Airport – the official weather reporting site for Washington, D.C.   Although not normally the case, the start of this September has coincided with the longest sustained stretch of hot weather of 2014. 

September features a wide variety of weather from one year to the next.  It can be cooler than average as September 2009 was when the month finished without any 90 degree temperatures.  That was a far cry from September 2010 which had 10 days with temperatures in the 90s.  Meanwhile, September 2011 was significantly wetter than average, with the remnants of Tropical Storm Lee bringing the Mid-Atlantic Region record rainfall.  In fact, September 2011 was the wettest on record in Baltimore.

This September has gotten off to a hot start with two days in the mid-90s in the Nation’s Capital and warmer than average weather poised to continue for the rest of the week.  That doesn’t mean, though, that the rest of the month will experience similarly hot weather, but does highlight the fact that September often features highly variable weather.  Also, September is the most active month of the hurricane season and the Mid-Atlantic Region could be impacted by a tropical system at some point this month. 

In fact, Tropical Storm Dolly was named last night and will avoid our region as it makes landfall in Mexico.  Today is also the 79^th anniversary of the first of only three Category 5 hurricanes in recorded history to make landfall in the United States.  The Florida Keys were decimated by the historical hurricane on this date in 1935.  However, there are no hurricanes anywhere in the Atlantic Ocean today.