Severe Thunderstorms
Severe Thunderstorms| Severe thunderstorms can strike any time of the year. Severe thunderstorms and tornadoes, are more frequent in the spring months of March, April and May. Tennessee also has a "secondary" severe weather season in November and December. Severe thunderstorms can, and do, occur anytime of the day and night and during any month of the year. Damaging thunderstorm winds are much more common in Tennessee than tornadoes. The National Weather Service defines a thunderstorm as severe when wind speeds reach 58 mph (50 kts) or stronger and/or 3/4 in hail (or larger) falls from the storm. Winds from severe thunderstorms can well exceed 100 mph, overturning trailers, unroofing homes, and toppling trees and power lines. Most of the storm damage in the Mid-South is caused by straight line winds from thunderstorm downbursts. Severe Thunderstorm wind speeds may equal the wind speeds of weak to strong tornadoes. All thunderstorms are capable of producing deadly lightning. PLEASE NOTE: Severe thunderstorms can produce tornadoes with little or no warning!! Severe Thunderstorm Safety Rules FIND SHELTER IMMEDIATELY. Go to a sturdy building that will withstand high winds. Avoid electrical appliances, metal pipes and corded telephones. When a Severe Thunderstorm Warning is issued for your location, treat it the same as you would a Tornado Warning. Remember that severe thunderstorms can produce damaging winds, large hail and deadly lightning. Hail Size Estimates (Diameter in inches) Pea............ 1/4 inch Golfball....... 1 3/4 inch Penny......... 3/4 inch Tennis Ball... 2 1/2 inch Quarter....... 1 inch Baseball...... 2 3/4 inch Half Dollar.... 1 1/4 inch Grapefruit..... 4 inch Wind Speed Estimates Speed (MPH) Effects 25-31 ............... Large branches in motion; whistling in telephone wires 32-38 ............... Whole trees in motion 39-54 ............... Twigs break off of trees; wind impedes walking 55-72 ............... Damage to chimneys and TV antennas; pushes over shallow rooted trees 73-112 ............. Peels surface off roofs; windows broken; trailer homes overturned 113+ ................ Roofs torn off houses; weak buildings and trailer homes destroyed; large trees uprooted. |