This is because of an increased frequency of certain tornado-producing weather patterns (say, hurricanes in south Texas, or northwest-flow weather systems in the upper Midwest).ĭoes hail always come before the tornado? Rain? Lightning? Utter silence? Some areas of the US tend to have more paths from a specific direction, such as northwest in Minnesota or southeast in coastal south Texas. Some tornadoes have changed direction amid path, or even backtracked. Most move from southwest to northeast, or west to east. What direction do tornadoes come from? Does the region of the US play a role in path direction? Tornadoes can appear from any direction. The details behind these theories are given in several of the Scientific References Mathematical modeling studies of tornado formation also indicate that it can happen without such temperature patterns and in fact, very little temperature variation was observed near some of the most destructive tornadoes in history on. Recent theories and results from the VORTEX programs suggest that once a mesocyclone is underway, tornadoĭevelopment is related to temperature changes across the edge of downdraft air wrapping around the mesocyclone (the Tornado formation is believed to be dictated mainly by things which happen on the storm scale, in and around the mesocyclone. Occur from supercells-which are rotating thunderstorms with a well-defined radar circulation called a mesocyclone. The most destructive and deadly tornadoes The truth is that we don't fully understand. Even when the large-scale environment is extremely favorable for tornadic thunderstorms, as in an SPC "High Risk" outlook, That form under those conditions (near warm fronts, cold fronts and drylines respectively) never make tornadoes. How do tornadoes form? The classic answer-"warm moist GulfĪir meets cold Canadian air and dry air from the Rockies"-is a gross oversimplification. How close must two or more different tornadic circulations become to qualifyĪs a one multiple-vortex tornado, instead of separate tornadoes? There are no firm answers. At what wind speed of the cloud-to-ground vortex does a tornado begin? Mobile radars also have showed that tornadoes often extend outside an existing, visible funnel. It is well-known that a tornado may not have a visible funnel. Meteorologists also can disagree on precisely defining large, intense, messy multivortex circulations, such as the El Reno tornado of 2013, compared to the parent mesocyclone and surrounding winds of damaging intensity. There is also disagreement as to whether separate ground contacts of the same funnel constitute separate tornadoes. For example, the difference is unclear between an strong mesocyclone (parent thunderstorm circulation) on the ground, and a large, weak tornado. However, to classify and define tornadoes (per this essay by Doswell). Weather scientists haven't found it so simple in practice, What is a tornado? According to the Glossary of Meteorology (AMS 2000), a tornado is "a violently rotating column of air, pendantįrom a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud." The wording of other definitions may vary, but one constant is this: a tornado must must be in contact with the ground and a convective cloud at the same time. However, credit should be given to NOAA for use of images, unless labeled otherwise. NOTE: All images found in FAQ pages on this site must be public domain and Those with some meteorological education and training. There is also a partial list of technical scientific references related to tornadoes for The intent here is to direct you to the best tornado info available, regardless of domain.
None of the links to outside websites implies any kind of commercial Some of the trustworthy sites are linked from the answers below. Web addresses also may change often.Īs with any other subject, please proceed with great caution online when investigating tornadoes. There are many good websites with tornado information (especially in NOAA, the National Weather Service and FEMA), but also, many inaccurate and unreliable ones. Severe storms so if you are doing your own research or school reports, Recent books from your local library or a major university libraryĪre still the deepest resource for learning about tornadoes and other Which will link you to more detailed information if you desire. Instead, it is a quick-reference summary of tornado knowledge, Tornado FAQ is not intended to be a comprehensive guide to tornadoes. If you find a link not working or an error of any sort, please e-mail the FAQ author directly. Questions asked of the SPC as well as basic tornado research informationĪnd countless scientific resources. This list of Frequently Asked Questions (FAQ) has been compiled from The Online Tornado FAQ (by Roger Edwards, SPC)
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