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This module compiled with information courtesy of the official NOAA Storm Spotters Guide. This page contains sponsored links.
 
SECTION ONE:
GLOSSARY As in the other sections, you can click on the glossary image wherever you see it, and the glossary will open in another window. Just close that window when you are ready to continue.

THUNDERSTORM DANGERS:
SAFETY TIPS:

When spotting/chasing, travel in pairs whenever possible. When moving, this will allow the driver to remain focused on the chore of driving while the passenger keeps an eye on the sky and handles any communications. When stopped, two sets of eyes are available for observation.

Keep aware of the local environment at all times. When in the vicinity of a thunderstorm, it would be preferable to keep at least a two mile "buffer zone" between you and the storm. Frequently check the sky overhead and behind to ensure no unexpected events (such as a new tornado) are developing. Always, ALWAYS have an escape route available, in case threatening weather approaches or you get within the two mile "buffer zone". A good motto to remember is to "keep your head on a swivel". Also remember, one of the greatest dangers while mobile spotting or storm chasing is DRIVING. Be aware that many people are not used to driving in bad weather conditions. Also be VERY aware of hydroplaning conditions. It doesn't take much water on the road to cause your vehicle to hydroplane. For more information on hydroplaning, please read the SAFETY GUIDE.

 
LIGHTNING:
Let's review the destructive and deadly thunderstorm elements before introducing the thunderstorm spectrum. By definition, all thunderstorms contain lightning. In most years it is the thunderstorm's greatest killer. A possible contributing reason for this is that lightning victims frequently are struck before or after the occurrence of precipitation at their location. Many people apparently feel safe from lightning when not experiencing rain. This image of lightning was taken while storm chasing, coming very close to the chase vehicle.
GLOSSARY
FLASH FLOODING:
Cases involving either slow-moving thunderstorms or series of storms which move repeatedly across the same area (sometimes called train-echo storms) frequently result in flash flooding. The total number of flash flood deaths has exceeded tornado fatalities during the last several decades. Two factors seem to be responsible for this: public apathy regarding the flash flood threat and increased urbanization. When concrete replaces soil, rain water will run off rather than soak in. Flash flood producing rainfall has made this type dramatic rescue attempt all too familiar lately, especially in urban areas and popular mountain camping spots.
HAIL:
This hailfall occurred near Clayton, New Mexico in 2003. At times it reached the size of tennis balls! Hail causes more monetary loss than any other type of thunderstorm-spawned severe weather. Annually, the United States alone suffers about one billion dollars crop damage from hail. Hail rarely kills people, but these were hollow words in China in May, 1986 when 100 people were killed, 9000 injured, and 35000 homes destroyed by an intense hailstorm. Hail also killed a man in Ft. Worth, Texas in 2000, when he was struck in the head trying to get to his car to move it from a tornados path.

GLOSSARY
THUNDERSTORM OUTFLOW:
Thunderstorm winds also cause widespread damage and occasional fatalities. Thunderstorm "straight-line" winds originate from rain-cooled air that descends with the accompanying precipitation. This Kansas Derecho windstorm, approaching from the north, was packing 80+ MPH winds (measured by chase vehicles at a maximum of 106 mph behind the spectacular appearing gust front. These same thunderstorms earlier produced several small tornadoes, grapefruit size hail, and flash flood rainfall before merging.
OUTFLOW DRIVEN DUST:
After the thunderstorm gustfront passes and before precipitation, if any, arrives, blowing dust often is kicked up by thunderstorm induced winds. The amount of dust depends on soil type, soil moisture content, and wind intensity. Winds were estimated to be about 50 MPH at this time along near Seminole, Texas. Severe thunderstorm winds are especially dangerous to aviation interests, particularly aircraft which are on final approach or taking off in the presence of thunderstorm outflow winds.
A gust front marked by blowing dust near Altus, OK October 1, 1998. If you were in this position you could soon expect high winds (and possibly blowing debris).

Gust front during a derecho event that began in Kansas May 27, 2001 and progressed south and east well into central Texas.

GLOSSARY
DOWNBURSTS:
Damaging thunderstorm winds have been termed downbursts by renowned severe storm researcher Dr. Ted Fujita. Dr. Fujita further classifies these events as macrobursts (greater than 2.5 miles in diameter) and microbursts (less than 2.5 miles in diameter). Generally, a macroburst is on the scale of the entire cold air outflow field of a thunderstorm or a group of thunderstorms; whereas the microburst is a sub- thunderstorm scale outflow feature.
MICROBURSTS IMBEDDED IN MACROBURSTS:

above photo by Moller

In the top image we see a classic microburst occurring. This is a southward view from within a mile of a microburst imbedded within a macroburst. The transition line from ragged to smooth cloud texture, to the left and above the microburst, is where the right to left-advancing macroburst meets cloud base. This is the leading edge of the thunderstorm gustfront ahead of a line of thunderstorms. Immediately behind the gustfront and to the right side of the highway, the microburst has reached ground and is in the process of "curling" over the highway. Estimated wind speeds from moving dust parcels were 70 MPH.

In the next picture we can see a broad macroburst area which has kicked up dust out to the right of it for several miles, even thought the "wet" part of it didn't reach out that far.

We will have more on the visual identification of microbursts later.

Beautiful microburst in progress.

 
TORNADOS:
Last but not least is the tornado. Again, a tornado is defined as a violently rotating column of air in contact with the ground and a pendant from a thunderstorm (whether or not a condensation funnel is visible to the ground). Winds during a tornado can range from 40mph to 318mph depending on the scale of the tornado...meaning the winds can go from picking up small objects like newspapers and Medifast coupons, to destroying whole houses. It's important to remember the damage a tornado can cause, & to keep safety in mind always. If a tornado is approaching your location, drive away from the tornado at a 90 degree angle IF you are in open country, IF the location and motion of the tornado are known, and IF you are familiar with the local road network. If you are in an urban area and escape is not possible for some reason, abandon your vehicle and get into a reinforced building. If one is not available, get into a culvert or ditch, or other low lying spot in the ground (that is not flooded).

 

GLOSSARY

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