After a series of vicious tornado outbreaks hit the state of Texas in 1947 the state placed special emphasis on volunteer spotting and the local weather offices began to offer basic training classes to the general public. Spotting required the delivery of timely information so that warnings could be issued as quickly as possible, thus civilian land line phone calls and amateur radio operators provided the most efficient and fastest means of communication. While phone lines were reliable to a degree a common problem was the loss of service when an approaching storm damaged phone lines in its path, this eventually lead to amateur radio becoming the predominant means of communication and resulted in the installation of special amateur radio work zones within local weather offices. Volunteer spotters would come into the local office and run a radio net from within directly relaying information to meteorologists.
The 1950s saw the deployment of the first dedicated weather radars in the United States and by this time civilian spotter networks were commonplace. The new reflectivity only radars provided meteorologists with basic information and helped identify potentially severe storms but due to the nature of weather radar, most precipitation is detected at a height of 1 kilometre or more above the ground. Ultimately the radar cannot see what exactly occurs at the surface of the earth and storm spotters now correlated ground truthing with radar signatures.
The 1960s through to the present has seen the development of new spotter technologies and training techniques. Prior to 1960 the vast majority of amateur radio communication relied on AM modulated signals and the use of simplex. It was not uncommon for spotters to only hear the distant net control station and not hear other mobile or base stations which were much closer. After 1960 amateurs adopted the use of FM repeaters which operated in the VHF spectrum. The use of FM repeaters was a huge advancement for storm spotters, spotters could now hear each other regularly. The low noise floor and greatly improved audio quality meant much better signal reception for all stations. By the 1970s nearly all spotter radio activity consisted of half-duplex FM repeater use. The next major technology to aid spotters was the development of the cell phone in the late 1970s and early 1980s. It was now possible for non-amateur radio operators to directly report severe weather.
The late 1980s and early 1990s would popularize spotting and its public perception. During this period a number of NSSL (National Severe Storms Laboratory) projects were carried out, some of which were documented and broadcast on television in a number of specials. Spotters and their actions were attributed to saving lives as well as aiding university research groups who would drop sensors such as TOTO in the path of tornadoes and at times fire rocketsondes directly at or very close to tornadoes. At about the same time early storm chasers were popularized and associated with spotters. It is believed this association is what has led many in the present era to associate storm chasers and storm spotters as carrying out the same actions or having the same goals.
The primary group responsible for storm spotting in the USA is known as Skywarn. A Skywarn group is either directly or indirectly affiliated or associated with the local weather office and in many cases other agencies responsible for the well-being of individuals. Today, amateur radio still plays a key role as most spotters opt to attain their radio licenses, however cell phones are an ever increasingly popular means to directly relay information as well.
Other spotters groups have formed in various countries. Canwarn is the Canadian spotter program run by Environment Canada and similarly the Australian Bureau of Meteorology runs the ASP (Australian Storm Spotters) program in Australia. In the United Kingdom, the TORRO operates a network of observers. Several European nations are also organizing spotter networks under the auspices of Skywarn Europe
There have also been recent complaints that mobile spotters are a danger to others on the road. Mobile spotters commonly park their vehicles on the shoulder for a short time while they observe. In some areas parking on the shoulder is only allowed in emergency situations and it is also believed that spotters pose a distraction to others driving. Most spotter groups do support parking on the shoulder as long as it can be safely done and there is no other alternative. The use of amber lights to alert drivers that a spotter vehicle is parked is also highly recommend. One controversy which has emerged is the use of such lights. Light bars and strobe lights have been becoming increasingly popular with the storm spotting and storm chasing community since both groups often travel in less than ideal weather conditions where visibility may be limited. However in recent years some spotters have been seen using red, blue, white and/or green lighting devices apparently imitating emergency vehicles. Such actions are illegal in most areas and are highly condemned by both the spotter and storm chaser community, "flashing light bars added to your chase vehicle (similar to those used by law enforcement) may be illegal in some places and their use to imply some sort of official status to your chasing is probably going to get you in trouble".
Storm spotters generally operate in a local area with their primary purpose being the observation and reporting of severe weather. Storm chasers generally travel, with the primary goal being the observation and documentation of severe weather through pictures and video. Confusion of the two occupations is possible as there is overlap between both groups' activities. Many spotters do carry photo and video equipment to document severe weather and damage, which may be used as training material for future spotters and historical evidence. Additionally, chasers report storms to aid spotters, and take part in spotter training sessions.
After 1996 with the explosion of storm chaser interest there was a move by many spotter groups to distance themselves from storm chasers for fear of being perceived in a negative light. However it should be noted that in many cases this was a temporary short-term move to protect against any backlash from emergency management officials. Today spotters and storm chasers work together in the field when conveying data and generally benefit from one another.