MAYVILLE – Between 4:00 and 6:00 PM on Saturday July 24, 2010, a line of supercell thunderstorms crossed into the Southern Tier of Western New York, producing four confirmed tornadoes.
On a synoptics scale, the event was well forecasted days in advance. The NOAA Storm Prediction Center had our region under a standard “Slight” Risk for severe thunderstorms that afternoon. On the day of the event, Western New York was wedged in a “warm sector”, which is the area between a warm and cold front, and limited sunshine broke out for the early afternoon, helping to further destabilize the atmosphere.
An area of broad rotation developed along a squall line out to our west. That squall line continued to intensify as it moved across Lake Erie, with popup rotating supercell storms blossoming out ahead of the main storm line. As the main line inched closer to these individual storms, their rotation further increased.
It is important to remember that forecasters cannot see tornadoes on Doppler radar; we’re only seeing the thunderstorm that is producing the potential tornado. However, forecasters are trained in radar display visuals to know how to spot potential trouble areas within a thunderstorm.
The National Weather Service in Buffalo issued a Severe Thunderstorm Warning for Chautauqua County at 3:41 PM in advance of these cells. The office quickly upgraded to a Tornado Warning at 4:08 PM, with multiple Tornado Warnings issued downstream as the storms moved eastward through Chautauqua and Cattaraugus Counties.
The first tornado of the afternoon touched down west of Mayville at 4:40PM, crossed Chautauqua Lake (becoming a waterspout for a brief time), came ashore near Lakeside Park, before lifting near Dewittville. The National Weather Service determined on storm surveys that the tornado had winds of 125 MPH, classing the tornado as an EF2 on the Enhanced Fujita scale.
A second EF2 occurred near Randolph around 5:25 PM, crossing Interstate 86, before lifting near Steamburg. These twin EF2’s caused significant damage to homes and businesses in Chautauqua and Cattaraugus Counties.
The third tornado touched down in the town of Great Valley at 5:25 PM and was rated an EF1.
The fourth and final tornado in this event occurred at 5:50 PM near Carrollton, crossed Interstate 86 into the village of Allegany, before lifting near St. Bonaventure University. While this tornado was only rated an EF1, the official damage path of the tornado was 7 miles, which is a bit unusual. Most EF0 and EF1 tornadoes tend to be shorter-tracked, with a textbook definition of under 3 miles, but there’s always going to be that one outlier.
As we all know, tornadoes can happen in Western New York. It is important to be prepared; have a NOAA Weather Radio in your home and download a good smartphone app that is designed to push watches and warnings. Make sure you have a plan for tornado warnings; find a place in your home to designate as your “safe spot” for tornado warnings.
A basement works best, but a general rule of thumb is a small room (hall closet, bathroom, etc), lowest floor of your house, near the center (put as many walls between you and the outside as you can), and away from windows. If you are in a car or a mobile home, you must exit and find more substantial shelter.
WNYNewsNow Multimedia Journalist Justin Gould contributed to this report.