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F0 Tornado in Southern Cayuga County
April 18th, 2004

At 143 pm EDT Sunday April 18th, a small tornado touched down briefly in the southeast part of the town of Scipio in southern Cayuga County. The tornado was rated an F0 on the Fujita Scale of tornado intensity which has winds between 40 and 72 mph. A National Weather Service survey team determined that the maximum winds with this small tornado were about 70 mph. The tornado first touched down on Mather Roads(county route 428) close to Kennedy Road and tracked east southeast to Fire Lane 10 on Route 38 before lifting by the time it reached Owasco Lake. Most of the damage from the tornado was to trees which were either snapped off or uprooted. There was some minor structural damage to several structures in the path of the tornado including a roof that was partly torn off a home, and a small boat that was overturned. A row boat was found up in a tree!

Map of Southern Cayuga County Where the Tornado and Downburst winds occurred Purple areas - show images of damage caused by straight line winds. Red areas - show images of tornado damage.
Tornado Path (red) in southern Cayuga County. Purple outlines are areas where there were strong damaging straight-line winds between 60 and 70 mph. These straight line winds were associated with the thunderstorm that produced the small tornado. Click on the purple or red areas on the map or links above where the damage paths are, to see the damage photographs.

In addition to the damage directly attributed to the tornado, there were scattered locations around the southern part of the county that had significant straight-line wind damage from the thunderstorm that spawned the tornado. This is common as thunderstorms capable of producing tornados often have areas of intense winds and large hail. The strong straight-line winds with this storm were associated with what meteorologists call the Rear Flank Downdraft (RFD) of the thunderstorm. This downdraft often is a precursor to tornadic development and can have damaging winds. In this event, the RFD caused more damage than the tornado itself, blowing a roof off of a house, damaging numerous barns, silos and knocking down many trees. In some instances the damaging straight-line winds were as strong as the tornado. The map below highlights the areas that were most impacted by the straight-line RFD winds (purple) and the tornado (red).

Schematic of a supercell thunderstorm and rear and forward flank downdrafts To the right is a schematic of a tornadic thunderstorm (click on the schematic for a larger image). A key chacteristic of tornadic thunderstorms is that they rotate or spin rapidly. It is this spin that can produce a tornado and often damaging straight-line winds and hail. Damage from straight-line winds can come from the Rear Flank Downdraft as in the case above and also from the Forward Flank Downdraft of which we did not see much if any damage.

The main point to remember is that there could be significant damage from other parts of a thunderstorm that produces a tornado. So, even if you don't get directly hit by the tornado, you could still have damaging winds and large hail. So when the National Weather Service issues a tornado warning, even if the tornado does not hit your location, you could still see damaging winds and large hail. It is important to heed all warnings for your safety.

Doppler radar velocity image of the mesocyclone induced by the rear flank downdraft The image to the right shows a Doppler Radar wind signature that prompted National Weather Service Meteorologists in Binghamton to issue this tornado warning for southern Cayuga County (click on the image for a larger view). It was the development of the strong winds from the rear flank downdraft of the thunderstorm that likely led to the development of the tornado in this case.
For a more in-depth look at the April 18th, 2004 severe weather event, read the case study on our Research page.

Posted May 18, 2004

National Weather Service
Binghamton Weather Forecast Office
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Johnson City, NY 13790
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Page last modified: May 29, 2009
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