Derecho or Wind Storm
A Derecho (deh REY cho), or sometimes called a “Bow Echo” due to the bent curve of the radar signature, is a wide spread, long-lived, line or cluster of strong thunderstorms, that rapidly moves east or southeast, and produces a large damaging wind field over the length of the storm.
The June 29, 2012 Radar Imagery Composite Summary below nicely shows an actual derecho that started near Chicago and eventually pushed into Washington DC over 12 hours time. Looking at this radar summary you will notice the largest width of the storm is over 240 miles, duration length of storm in the image nearly 450 miles (full path extended 700 miles into DC), and of course the signature “bow echo” or reverse “C” signature of a Derecho.
Specific Criteria for a Derecho:
- Fast moving, long-lived wind storm
- Violent thunderstorms coupled together
- Wind gust > 58 mph
- Wind damage extends > 240 miles
Information provided by iAlert.com
Before a Derecho
Some steps you can take to reduce property loss in a storm or high wind conditions:
- Trim or remove trees close to structures and secure outdoor items.
- Fasten straps or clips to building roofs to reduce damage.
- Use storm shutters or plywood for window protection.
- Make sure to secure or store any loose items on your property.
Stay inside during high winds if possible to prevent injuries, and have sufficient emergency supplies on hand for at least 72 hours. Remember to plan for those with special needs as well as for pets
If evacuation is suggested or required, it is advisable to secure outdoor items and shut off utilities. It is also a good idea to have a contact list, a building evacuation map and a predetermined meeting place. Be sure to discuss and practice evacuation plans with your family. Evacuation routes are usually marked, but it is beneficial to be aware of these routes ahead of emergencies. While traveling, avoid canyons or steep, sloped terrain and other potentially flooded areas. As little as six inches of water may stall a car, and a foot of water will float many vehicles. Local communities may offer additional resources and information for storms and wind events and other emergencies.
Additional resources are also available from:
