Modern Hurricanes to Impact the DC Metro Region

Flash Flood Watches are In Effect Today  (Source: NOAA)

As the remnants of Hurricane Florence shift northward, residents of the DC Metro Region will see moderate to heavy rainfall.  While 1” to 2” of rain are possible in spots, especially west of town toward the I-81 corridor, it pales in comparison to the record-setting rainfall that occurred in the Carolinas (where rain was measured in feet).

September is the busiest month of the Atlantic hurricane season.  Over the last 20 years, the DC Metro Region has endured significant impacts from hurricanes.

2012: In late October, Sandy became the most intense hurricane of the season as a Category 3 storm with sustained winds of 115 mph and an unusually low air pressure of 940 millibars (mb), compared to the average sea level air pressure of 1013.25 millibars.  By comparison, while at peak intensity over the open Atlantic Ocean, Hurricane Florence was a Category 4 hurricane with sustained winds of 140 mph and a minimum air pressure of 939 mb. 

Fortunately, Sandy weakened and was classified as a non-tropical system shortly before coming ashore in New Jersey.  However, “Sandy” still brought record-setting rainfall to the Nation’s Capital with tropical storm force wind gusts.  National Airport saw its second wettest October day on record with 3.85” on October 29, 2012, coupled with a peak wind gust of 61 mph.  Another 0.84” of rain fell in the Nation’s Capital on October 30, 2012.

2011: Hurricane Irene made landfall in North Carolina as a Category 1 on August 27.  National Airport saw a storm total of 3.83” of rain and a peak wind gust of 60 mph.  However, areas south and east of DC saw a lot more rain such as Waldorf, MD (6.70”) and Prince Frederick, MD (8.33”).  Irene’s rainfall in the Nation’s Capital was especially significant since it accounted for nearly half of the 8.92” of rain that month.  It was the wettest August in Washington, D.C. since 1967 (9.17”).  

2003: At peak intensity over the open Atlantic, Isabel was a rare Category 5 hurricane with sustained winds of 165 mph and a minimum central air pressure of 915 millibars.  It weakened considerably to Category 2 status before making landfall in North Carolina on September 18.  The center of Isabel tracked west of the DC Metro Region and caused significant tidal flooding along the Chesapeake Bay and Tidal Potomac River.  

Although the highest wind gust from Isabel at National Airport was 58 mph, a 71 mph wind gust was observed at the National Academy of Sciences downtown.  A daily rainfall record of 2.28” also occurred at National Airport on September 18.

1999: Hurricane Floyd made landfall in North Carolina as a Category 2 hurricane on September 16.  Although gusty winds occurred in the DC Metro Area, Floyd’s primary legacy was significant flooding.  That’s because grounds were already saturated following several days of heavy, thunderstorm-related rainfall in late-August 1999, combined with the remnants of Hurricane Dennis earlier that September.  According to the National Weather Service, a total of 3.67” of rain occurred at National Airport on September 16 along with a peak wind gust of 55 mph.

Daily Rainfall Records (Source: National Weather Service)

September 17:

Washington, D.C. – Reagan National Airport (DCA): 3.26” (1876)
Dulles International Airport, (IAD), Sterling, Virginia: 1.71” (2004)
Baltimore, MD (BWI Marshall Airport): 3.94” (1876)

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September 18:

DCA: 2.28” (2003)
IAD: 1.76” (2003)
BWI: 2.13” (2003)