Weather Watch

By DAVE NICOSIA

Fall severe weather

Many people consider the spring and summer months to be the most active for severe thunderstorms and tornadoes in our area but it is often overlooked that the fall season can have just as much severe weather. In fact, some of the most significant severe weather events of the recent past have occurred in the fall season.

For example, on September 7, 1998 (Labor Day), a line of severe thunderstorms called a "derecho" raced across the Syracuse area with wind gusts reaching up to 115 miles per hour. The damage path from the Labor Day Derecho was 30 miles long and was six to seven miles wide at certain locations. Unfortunately, three deaths were attributed to this storm with seven injuries.

An even more deadly fall season severe weather outbreak occurred on November 16, 1989. A line of severe thunderstorms moved northeast across central and eastern New York and eastern Pennsylvania during the midday hours. Very strong winds caused extensive damage to a cafeteria at the Coldenham Elementary School in Newburgh, N.Y. tragically killing nine children and injuring 21 others.

On October 18, 1990, a rash of thunderstorms with strong winds and small tornadoes affected the Mid-Atlantic States and Northeast United States. Some other notable fall season severe weather events occurred on November 11, 1995, November 8, 1996 and September 29, 1997.

With the arrival of the fall season, the winds in the upper atmosphere increase as the jet stream begins its seasonal march to the south over the northern United States. Colder air gathers to our north in Canada and leads to stronger cold fronts which drop south into our area. These cold fronts often clash with warm and humid air masses leftover from the waning summer. This combination leads to another annual maximum in severe weather in the northeast United States during the fall.

As this summer draws to a close and the incidence of severe weather increases again in our area, it is important to consider the following severe weather safety tips. If you plan to be outdoors, check the latest weather forecast and keep a weather eye on the sky. Watch for signs of an impending storm-towering thunderheads, darkening skies, lightning and increasing winds. When a thunderstorm threatens, the best place to be is inside a home, a large building or an all-metal (not convertible) automobile. Do not use the telephone except for emergencies. If you are caught outside, do not stand under a tall isolated tree or a telephone pole. Avoid projecting above the surrounding landscape. For example, don't stand on a hilltop. In a forest, seek shelter in a low area under a thick growth of small trees. In open areas, go to a low place, such as a ravine or valley.

The National Weather Service defines a severe thunderstorm as a thunderstorm that has winds greater than 57 mph or hail greater than three-quarters of an inch. Remember, all thunderstorms are hazardous since they contain deadly lightning. A severe thunderstorm watch is issued when conditions are favorable for severe thunderstorms in-and close to-the watch area, typically over the next three to six hours. During a watch, one should be ready to take quick action if a thunderstorm approaches. A severe thunderstorm warning means that severe thunderstorms are imminent or occurring. When a warning is issued for your area, take action immediately to protect you and your family.

One of the best ways to receive information about severe weather is through NOAA weather radio. NOAA weather radio is the voice of the National Weather Service (NWS) and each NWS office maintains several weather radio transmitters providing broadcasts of warnings, watches, forecasts and other hazard information 24 hours a day. Some weather radios are equipped with a special alarm tone feature that can sound an alert and give you immediate information about a life-threatening situation any time of day. Weather radios can be purchased at most stores that sell electronics for about the cost of a pair of shoes. Regular radios normally do not pick up the weather radio frequencies.

If you have any further questions about severe weather safety, visit the Binghamton National Weather Service web site at www.nws.noaa.vov/er/bym/prepare.html. You can also e-mail your question to me at david.nicosia@noaa.gov.

[Dave Nicosia is a Warning Coordination Meteorologist at the National Weather Service Binghamton. His column will run the first week of the month.]