PUBLIC INFORMATION STATEMENT
Wednesday, March 20, 2013
...2013 National Flood Safety Awareness Week...
The National Weather Service continues its annual Flood Safety Awareness Week today through Friday,
March 22nd. This year the National Weather Service is also commemorating the centennial anniversary
of the Great Ohio Valley Flood of 1913 which occurred between March 23 and 27th and was
the largest weather disaster in Ohio’s history.
The theme for today is tropical cyclones and inland flooding. June 1 through November 30 is the
official hurricane season. During each season, an average of 10 storms will develop in the Atlantic
Basin, 6 of which will likely become hurricanes. In addition to wind, tornadoes, and storm surge
flooding, many tropical systems produce inland freshwater flooding. Tropical cyclones can have life
threatening effects hundreds of miles inland.
Northern Ohio and northwestern Pennsylvania are not the first places you think of as being in
danger of hurricanes, however in the past century dozens of hurricane remnants have moved over the
region. Remnants of Hurricanes Frances and Ivan in September of 2004 brought torrential rain twice
within a weeks’ time resulting in widespread flooding in the Ohio Valley. These remnant storms
can pose just as dangerous a flood threat as a hurricane making landfall. When a hurricane
dissipates as it moves inland, it often takes several days to rain out all the tropical moisture it
had carried. The remnants will also often merge with other weather systems and frontal boundaries
which can increase the rainfall.
Factors affecting inland flooding.
Storm Speed- The slower the system moves, the more time for the rains to fall
over a location.
Orography-Lifting of the warm, moist tropical air over geographical barriers,
such as hills and mountains. Also the gradual increase in elevation as the system moves inland
amplifies and intensifies the rain.
Interaction with other weather features- Agnes (1972) fused with another storm
system, producing floods in the northeast U.S., which caused 122 deaths and $3.2 billion dollars in
Antecedent conditions-The wetness or dryness of the soil, the existing capacity
of the streams and rivers, ponds and lakes and reservoirs.
Additional information about Flood Safety Awareness Week can be found at WWW.FLOODSAFETY.NOAA.GOV or http://tadd.weather.gov. For more information
about the Great Ohio Valley Flood of 1913 please visit http://mrcc.isws.illinois.edu/1913Flood/.