Weather Watch

By DAVE NICOSIA

Tornadoes:
it can happen here

When one thinks of tornadoes, the first thing that often comes to mind is a large black funnel ripping through a field in the middle of Oklahoma or Kansas, far away from the hills of northeast Pennsylvania or central New York. Yes, the Great Plains are in the middle of tornado alley and, on average, do see more violent tornadoes than our area. But, history tells us that tornadoes can and will hit our region again. On average, central New York and northeast Pennsylvania sees about one tornado per year. The tornado and severe weather season usually begins in May, peaks in June and July, and ends in the fall.

Typically, many years pass without any significant occurrence of tornadoes. Every once and awhile, we can see several twisters touchdown in our region in one season. During rare instances, we can experience several violent and deadly tornadoes in one season. This was the case in 1998. May 31 and June 2, 1998 will go down as the two worst tornado outbreaks to hit our region in many years. Eighteen tornadoes touched down on those days in central New York and northeast Pennsylvania. Half of those tornadoes had winds well over 100 mph, with four of them having winds approaching 200 mph. Two people died from these outbreaks, with millions of dollars of damage. Lake Carey, PA, Promised Land State Park in Pike County, Broome County, NY and Otsego County, NY all had the strongest tornadoes on these days.

Another major tornado outbreak struck the region on May 2, 1983 when tornadoes with winds to 200 mph hit a few areas in central New York. On May 31, 1985, a major tornado outbreak struck PA, Ohio, Ontario and western New York. Forty-one Tornadoes touched down during this outbreak, which killed 75 people in the U.S. alone and caused 450 million dollars worth of damage. One of these tornadoes cut a mile-wide swath through state forest land in central PA. This tornado was observed climbing up and down 2,000-foot mountains, dispelling the common myth that hills and mountains somehow protect us from tornadoes in New York and PA. As this tornado demonstrated, tornadoes can easily track up and down our mountainsides. Simply stated, mountains offer little, if any, protection at all. Another example of this was the Broome County tornado in 1998 that struck the hill south of Binghamton. Many other tornadoes that have hit our region have shown no preference for valleys or mountains. They just occur wherever Mother Nature decides.

What causes tornadoes?

Tornadoes form when high heat and humidity combine with strong winds, which rapidly change direction with height in the lowest few thousand feet above the earth’s surface. Typically, strong southeast winds at the earth’s surface lie below even stronger southwest or west winds a few thousand feet up. These changing wind directions near the Earth’s surface induce a swirling motion to the wind, which is forced to rise when a thunderstorm develops. Thunderstorms in this environment tap into this swirling motion and begin to rotate. In many instances, strong rotation in a thunderstorm is a precursor to tornadic development. Often times, a tornado will touchdown soon after thunderstorms exhibit such strong rotation. National Weather Service (NWS) Doppler Radar is designed to detect rotation in thunderstorms before the tornado touches down. This has allowed the NWS to increase advance warning for tornadoes to about 10 minutes before the tornado touches down.

Here are some tornado safety rules:

In homes, the basement offers the greatest safety. Seek shelter under sturdy furniture, if possible.

In homes without basements, take cover in the center part of the house, on the lowest floor, in a small room such as a closet or bathroom, or under sturdy furniture. Keep away from windows.

In shopping centers, go to a designated shelter area (not to your parked car).

In office buildings, go to an interior hallway on the lowest floor, or to the designated shelter area.

In schools, follow advance plans to a designated shelter area, usually an interior hallway on the lowest floor. If the building is not of reinforced construction, go to a nearby one that is, or take cover outside on low, protected ground. Stay out of auditoriums, gymnasiums and other structures with wide, free-span roofs.

In automobiles, leave your car and seek shelter in a substantial nearby building, or lie flat in a nearby ditch or ravine.

In open country, lie flat in the nearest ditch or ravine.

Mobile homes are particularly vulnerable and should be evacuated.

Trailer parks should have a community storm shelter and a warden to monitor broadcasts throughout the severe storm emergency. If there is no shelter nearby, leave the trailer and take cover on low, protected ground.

It is also important to remember the difference between a tornado watch and warning. A tornado watch means conditions are favorable for thunderstorms to produce tornadoes in and close to the watch area. A tornado warning means that a tornado has been detected by radar or sighted by severe weather observers.

The best way to receive a tornado watch or warning or other severe weather information is through NOAA weather radio, the voice of the NWS.

For more information on tornadoes and tornado safety or NOAA weather radio, check out the NWS Binghamton web site at www.nws.noaa.gov/er/bgm or e-mail david.nicosia@noaa.gov.

[Dave Nicosia is Warning Coordination Meteorologist for the National Weather Service, Binghamton.]