Thunderstorms develop in warm, moist air in advance of eastward-moving cold fronts. These thunderstorms often produce large hail, strong winds, and tornadoes. Tornadoes in the winter and early spring are often associated with strong, frontal systems that form in the Central States and move east. Occasionally, large outbreaks of tornadoes occur with this type of weather pattern. Several states may be affected by numerous severe thunderstorms and tornadoes.
During the spring in the Central Plains, thunderstorms frequently develop along a "dry line," which separates very warm, moist air to the east from hot, dry air to the west. Tornado-producing thunderstorms may form as the dry line moves east during the afternoon hours.
Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere (pic 1).
Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical (pic 2).
An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation (pic 3).
Tornadoes are most likely to occur between 3 pm and 9 pm, but can occur at any time.
They may strike quickly, with little or no warning.
They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.
The average forward speed of a tornado is 30 mph, but may vary from stationary to 70 mph.
Tornadoes can accompany tropical storms and hurricanes as they move onto land.
Waterspouts are tornadoes that form over water.
Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.
Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.
Along the front range of the Rocky Mountains, in the Texas panhandle, and in the southern High Plains, thunderstorms frequently form as air near the ground flows "upslope" toward higher terrain. If other favorable conditions exist, these thunderstorms can produce tornadoes.
Lightning......When Thunder Roars, Go Indoors!
NO PLACE outside is safe when thunderstorms are in the area!!
If you hear thunder, lightning is close enough to strike you.
When you hear thunder, immediately move to safe shelter.
Safe shelter is a substantial building or inside an enclosed, metal-topped vehicle.
Stay in safe shelter at least 30 minutes after you hear the last clap of thunder.
Indoor Lightning Safety Tips
Stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity.
Avoid plumbing, including sinks, baths, and faucets.
Stay away from windows and doors, and stay off porches.
Do not lie on concrete floors, and do not lean against concrete walls.
Last Resort Outdoor Risk Reduction Tips
NO PLACE outside is safe when lightning is in the area.
If you are ever caught outside with no safe shelter, the following actions may reduce your risk:
Immediately get off elevated areas such as hills, mountain ridges or peaks
NEVER lie flat on the ground
NEVER use a tree for shelter
NEVER use a cliff or rocky overhang for shelter
Immediately get out and away from ponds, lakes and other bodies of water
Stay away from objects that conduct electricity (barbed wire fences, power lines, windmills, etc.)
UNDER NO CIRCUMSTANCES should ANY of the above actions be taken if a building or an all-metal vehicle is nearby
If Someone Is Struck
Victims do not carry an electrical charge and may need immediate medical attention.
Monitor the victim and begin CPR or AED, if necessary.