Storm Thunder and Lightning

Storm, thunder, and lightning By Chris L 10-18-05 First of all…what is a storm?... • A storm is a violent disturbance in the atmosphere. • Storms involve sudden changes in the air pressure, which in turn cause rapid air movements. Conditions that bring one kind of storm often cause other kinds of storms in the same area. For example, the conditions that cause thunderstorms can cause tornadoes. How do thunderstorms form? • Thunderstorms are heavy rainstorms accompanied by thunder and lightning. Thunderstorms form within large cumulonimbus clouds, or thunderheads. Most cumulonimbus clouds and thunderstorms form when warm air is forced upward at a cold front. Cumulonimbus clouds also form on hot, humid afternoons in the spring and summer. In both cases, the warm, humid air rises rapidly. As the air rises, it cools, forming dense thunderheads. Heavy rain falls, sometimes along with hail. What are the danger levels? • Single Cells Typically last 20-30 minutes. Pulse storms can produce severe weather elements such as downbursts, hail, some heavy rainfall and occasionally weak tornadoes. • Multicells (multicell cluster & line) Cluster: A group of cells moving as a single unit, with each cell in a different stage of the thunderstorm life cycle. Multicell storms can produce moderate size hail, flash floods and weak tornadoes. Line: Multicell line storms consist of a line of storms with a continuous, well developed gust front at the leading edge of the line. Also known as squall lines, these storms can produce small to moderate size hail, occasional flash floods and weak tornadoes. • Supercells Defined as a thunderstorm with a rotating updraft, these storms can produce strong downbursts, large hail, occasional flash floods and weak to violent tornadoes. How dangerous is a typical thunderstorm? • A typical thunderstorm is about 15 miles in diameter and lasts an average of 30 minutes. Nearly 1,800 thunderstorms are occurring at any moment around the world. Don't kid yourself, ALL thunderstorms are dangerous. Every thunderstorm produces lightning, which kills more people each year than tornadoes. Heavy rain from thunderstorms can lead to flash flooding. This is especially true in the western region of Colorado and in Utah, where heavy rains fall in the higher elevations producing flash flooding in the lower elevations. Strong winds, hail, down bursts, and tornadoes are also dangers associated with some thunderstorms. Predicting Thunderstorms • Meteorologists are responsible for forecasting where thunderstorms will form and how severe they may become pay close attention to two main factors: stability of the atmosphere, and wind shear. In order for thunderstorms to form, air parcels must rise up and become unstable. The larger the vertical extent of the unstable layer and the warmer rising parcels are relative to the temperature of the surrounding atmosphere, the stronger the storms can become. Vertical wind shear, changes in wind direction and wind speed with increasing altitude, can allow convection to become organized, longer-lived, and more violent In organized convection, the updraft region of a storm is able to remain isolated from the precipitation and subsequent downdrafts. In single-cell thunderstorms, rain and downdrafts falling into the updraft cut off the storm's fuel supply of warm, humid air. #1 thing is safety • Lightning can be deadly! Remember all lightning safety rules! While nothing offers absolute safety from lightning, some actions can greatly reduce your risks. • Generally speaking: If a storm approaches, avoid being in, or near, high places, open fields, isolated trees, unprotected gazebos, rain or picnic shelters, baseball dugouts, communications towers, flagpoles, light poles, bleachers (metal or wood), metal fences, convertibles, golf carts and water. • Stay indoors and don't venture out unless absolutely necessary • Also, do not use any electrical appliances but a radio is necessary in order to hear weather updates. A Thunderstorm… • Here is a picture of a thunderstorm (right) • The flashes, though, appear first because lightning travels faster than sound. Observe Lightning… • Some thunderstorms can be seen approaching, while others hit without warning. It is important to learn and recognize the danger signs and to plan ahead. • Because light travels much faster than sound. Lightning flashes can be seen long before the resulting thunder is heard. Estimate the number of miles you are from a thunderstorm by counting the number of seconds between a flash of lightning and the next clap of thunder. Divide this by the number five, this gives you an estimate of how much miles you are away from a thunderstorm. • Remember, just because you are far away from a storm thunderstorm does not mean you a totally protected from it. By Chris L Storm, Thunder, and Lightning