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ADVANCES IN NOAA TORNADO RESEARCH AND FORECASTING TECHNOLOGIES OVER THE LAST CENTURY

Photograph of tornado with the words "NOAA's Tornado Technologies and Forecasts" superimposed on top of the photograph. July 21, 2003 — Tornadoes are one of nature's most violent storms — capable of producing wind speeds greater than 250 mph and paths of destruction in excess of a mile wide and 50 miles long. In an average year, 1,200 tornadoes are reported across the United States, resulting in 80 deaths and more than 1,500 injuries. Tornadoes come in all shapes and sizes and can occur anywhere in the United States at any time of the year. In the southern states, peak tornado season is March through May, while peak months in the northern states are during the summer.

The NOAA National Weather Service issues more than 15,000 severe storm and tornado watches and warnings each year. Training and technological advances in tornado forecasting have increased average lead time for warnings from six to 11 minutes from 1994 to 2002, allowing individuals and communities more time to prepare for tornadoes by seeking shelter and securing property. But, advanced technologies are not worth much if people don’t use the information. Advanced tornado forecasting technologies must be coupled with effective local emergency preparedness plans and education that improves the public's response during severe weather events. Fortunately, advances in tornado alert systems, along with aggressive communications, awareness and outreach efforts, have also contributed to saving countless lives each year.

NOAA’s Tornado Activities
In general, the NOAA National Weather Service issues tornado watches and warnings, and NOAA Research works to better understand these powerful storms and improve forecasting techniques. Tornado watches are issued for the 48 contiguous states by the NOAA Storm Prediction Center located in Norman, Okla., while tornado warnings are issued by each of the 122 local NOAA National Weather Service forecast offices located throughout the United States. Meteorologists rely on Doppler weather radar to provide information on developing storms. The network of 122 WSR-88D, or NEXRAD, radars that blankets the nation detects strong rotation within the storm. Forecasters use this valuable data to determine the likelihood of a tornado and issue the appropriate watches and warnings.

NOAA Entities Involved in Tornado Research and Forecasting
Several NOAA organizations are dedicated to providing accurate tornado forecasts and warnings and conducting research to further improve forecasts and daily forecast operations to protect life and property:

NOAA National Severe Storms Laboratory: The National Severe Storms Laboratory, headquartered in Norman, Okla., leads the way in investigating all aspects of severe and hazardous weather. NSSL was established in 1964 and is part of NOAA Research. It is the only federally-supported laboratory whose mission is to focus on severe weather. The lab’s scientists and staff explore new ways to improve understanding of the causes of severe weather and ways to use weather information to assist NOAA forecasters, as well as federal, university and private sector partners. Over its history, NSSL has significantly improved the nation’s ability to forecast and warn of severe weather events by advancing the understanding of weather processes, improving forecast and warning techniques, developing new operational applications and transferring this knowledge to the NOAA NWS and other public and private sector agencies.
NSSL's important role in tornado research is perhaps best demonstrated by VORTEX, the Verification of the Origin of Tornadoes Experiment, a large field experiment that brought together the scientific community to study how tornadoes form. VORTEX resulted in a rich data set that scientists are using to determine the physical processes that generate and maintain tornadoes and then allow them to dissipate — information that will ultimately help to improve severe storm warnings.
NOAA Storm Prediction Center: The Storm Prediction Center issues forecasts/outlooks and watches for tornadoes (and other severe weather) over the contiguous United States — indicating areas at risk for severe weather (note that they do not issue severe weather warnings — only local weather forecast offices can issue warnings). Part of the Weather Service’s National Centers for Environmental Prediction, SPC meteorologists are on duty 24 hours a day, seven days a week. Established in Washington, D.C., in 1952, the center moved to Norman, Okla., in 1997. The center coordinates with NWS field offices around the country for short-term aspects of hazardous weather, including tornadoes. SPC makes maximum use of observations, numerical forecast models, Doppler radar and geostationary satellites to generate its forecasts. The SPC also provides internal scientific support and techniques development, including developing, evaluating and testing forecast methods.
NOAA Warning Decision Training Branch: Established in 1989 in Norman, Okla., the NOAA Warning Decision Training Branch develops and delivers training on the integrated elements of the warning process within a NWS forecast office. As part of the NWS Training Division, the WDTB training activities provide basic and advanced NEXRAD Doppler radar operator proficiency, with an emphasis on the integrated data environment, warning methodology and situational awareness. The WDTB’s goal is to increase expertise among NWS personnel in order to better serve the public in warning situations.
The Weather Event Simulator was developed by the WDTB as a severe weather forecast training tool — similar in concept to flight simulators used for pilot training. The simulator was designed to keep forecasters ready to deliver accurate, life saving forecasts. Studies from the Departments of Defense and Transportation, and the private sector, have shown 25 hours of quality simulation training is equivalent to about two years of experience. The simulator has been such an effective training tool that it has now been installed in all 122 weather forecast offices and 13 river forecast centers around the country.
NEXRAD Radar Operations Center: The NEXRAD Radar Operations Center provides centralized meteorological, computer software, maintenance and engineering support for all 158 NEXRAD (WSR-88D) radar systems deployed worldwide. Supported by the Departments of Commerce, Transportation and Defense, the ROC is responsible for modifying and enhancing the WSR-88D systems during their operational life to meet changing requirements, technology advances and improved understanding of the application of these systems to real-time weather operations. The ROC operates a 24-hour, seven-day a week help desk that assists radar sites with technical support more than 12,000 times each year. The ROC also operates WSR-88D test systems for the development of hardware and software upgrades to enhance maintenance, operation and provide new functionality. The ROC was established in 1987.

Note that the above four NOAA entities, along with the National Weather Service Norman Forecast Office, are all co-located in Norman, Okla., forming what is known as the NOAA Weather Partners.

NOAA Forecast Systems Laboratory: Located in Boulder, Colo., and part of NOAA Research, FSL conducts applied meteorological research and development to improve and create short-term warning and weather forecast systems, models and observing technology. Supercomputing and other leading-edge technology are used in these applications. FSL then transfers the new scientific and technological advances to its clients, which include NOAA's NWS, the commercial and general aviation communities, the U.S. Air Force, many foreign weather forecasting offices and various private interests.
In cooperation with operations specialists, FSL first developed and now continuously upgrades forecasting software, called the Advanced Weather Interactive Processing System (or AWIPS), used by the NWS. AWIPS is a high-speed computer system that allows forecasters to display and analyze satellite imagery, radar data, automated weather observations and computer-generated numerical forecasts – all in one workstation. FSL is also investigating the use of the Linux operating system, high speed networks and PC technology to make forecasting even more efficient and effective.
NOAA National Weather Service Forecast Offices: National Weather Service Forecast Offices located in communities around the country issue severe weather forecasts and warnings directly to the public through their partners in the news media, as well as over NOAA Weather Radio. A total of 122 modernized forecast offices work closely with emergency managers in ensuring the safety of the general public. In addition to issuing warnings, these offices educate the public on severe weather preparedness through the StormReady program. StormReady helps community leaders and emergency managers strengthen local safety programs. One such community, Van Wert, Ohio, earned a January 2002 NWS StormReady designation. When a Nov. 10, 2002, F4 tornado swept along its 53-mile path claiming four lives, the community was ready and already taking shelter. A series of warning alert radios in public locations — like the town’s movie theater — barked NWS tornado warnings, sending more than 50 adults and children to shelter just minutes before the powerful tornado tore off the building’s roof and tossed cars into the screen and front seats where kids and parents had been watching a movie. Only the tornado warnings issued by the weather service and the actions of the community through StormReady prevented a greater loss of life. Current weather watches and warnings from local forecast offices are also available on the Internet.
NOAA National Weather Service Regional Headquarters: Six NWS Regional Headquarters located in New York, Missouri, Texas, Utah, Alaska and Hawaii provide real time operational support to the 122 NWS offices throughout the nation. The support is essential to the NWS’s capability to provide weather warning and forecast services necessary for the protection of life and property. Prior to significant weather events, the regional headquarters review field readiness and may deploy staffing resources to ensure that forecast and warning offices are adequately staffed to meet the increased workload demands. They ensure the readiness of communications circuits. They provide emergency maintenance support to ensure that critical equipment (such as weather radars, NOAA Weather Radio transmitters, etc.,) remain operational prior to and during severe weather. Regional staffs host and maintain the regional Web farms, which provide the NWS presence on the World Wide Web. Regional headquarters also ensure NWS product and service consistency and quality through site visitation and evaluation programs.
One of the region’s most important tasks is to work closely with state and local emergency management officials in developing plans to deal with weather disasters and to serve as a liaison between WFOs and state and local emergency management agencies during severe weather events. For example, the NWS Southern Region maintains a Regional Operations Center (ROC) that shifts to a 24-hour operation prior to and during tornado outbreaks, tropical storms, floods or other major severe weather situations to support efforts of the WFOs and emergency management officials directly affected by the event and to supplement media communications.

The Regional Headquarters structure puts government decision makers closer to the partners and customers who are using NWS services, while maintaining cost effective use of personnel resources. One of the NOAA National Weather Service's greatest strengths is its local expertise, the familiarity WFO staffs have with their county warning and forecast areas and the close working relationships they maintain with NWS partners and customers in local communities. Ultimately, the primary function of NWS regional headquarters is to provide the planning and support services that allow front line offices to provide forecast and warning services.

All of these NOAA entities work together to make sure the latest scientific advances are rapidly incorporated into severe weather forecasts, watches and warnings.

Progress in Forecasting Tornadoes
Over the years, there has been much progress in tornado research and forecasting technologies:

Tri-State Tornado of 1925: Early in the 20th Century, tornado forecasting and warnings did not exist. Although the Tri-State (i.e., Missouri, Illinois, and Indiana) Tornado of 1925 still holds some significant NWS records, forecasters of the time didn't have the technology to help them predict, identify and track severe weather. After all, it was 1925 — the year of the Scopes Monkey Trial, Prohibition, silent movies, Flappers and Duesenbergs as the classy transportation. Calvin Coolidge was elected president that year, Lon Chaney starred in the silent version of Phantom of the Opera and Art Deco was just coming into vogue. Government offices were lucky to have telephones, and the first satellite was more than 40 years in the future. There was no NOAA Weather Radio, nor were there thousands of commercial radio and television stations to provide information to the public. In fact, there was no organized warning system in existence. In the aftermath of the tornado, 695 people were dead and more than 2,000 were injured; 15,000 homes were destroyed. Schools and businesses in 19 communities were left in shambles; and dazed survivors were left to pick up the pieces.
If the Tri-State Tornado occurred today, at least four NWS offices would be watching the storm even as it formed. The Storm Prediction Center in Norman, Okla., would issue tornado watches for the three-state area. Weather radar, satellites and weather models — run on a super-computer — would provide forecasters with information about what was coming hours in advance. Forecasters at local offices throughout the area would issue warnings and track the storms. Weather Radio transmitters, operated by NOAA National Weather Service personnel, would provide advance warning to the public, the media and local emergency managers. Spotter networks would be called out in force along the projected storm path, and local emergency managers would sound warning sirens as they received word of the approaching maelstrom. Local radio and television meteorologists would add their touches to repeated break-ins of normal programming. And, many of the people killed and injured would have had time to seek adequate shelter from the tornado.
The First Tornado Forecast in 1948: The first tornado forecast occurred on the evening of March 25, 1948, when a tornado roared through Tinker Air Force Base (AFB), Okla., causing considerable damage (i.e., $6 million dollars), a few injuries, but no fatalities. However, the destruction could have been much worse if a few hours earlier Air Force Captain Robert C. Miller and Major Ernest J. Fawbush had not correctly predicted that atmospheric conditions were ripe for tornadoes in the vicinity of Tinker AFB. The forecast issued by Fawbush and Miller was the first step in establishing the organized warning and watch program that blankets and protects the nation today.

Tornado Forecasting Technologies Used Today: Technology has provided a vast amount of information for today’s weather forecasters to use as they make critical forecasts and warning decisions. Forecasters use a variety of sophisticated tools to predict and track the weather, including satellites, radars, weather balloons and surface observing systems. Satellite imagery is a technology used by forecasters to track weather features that occur, such as precipitation and wind patterns. Radar data is used extensively for warning operations, such as issuing more accurate warnings in the case of severe weather (note, however, that although the computer will give indications, it is still up to the forecaster to interpret the meteorological data it provides to make a forecast or issue a warning). Surface observing systems are also used to give the forecaster “ground truth” data. Forecasters get upper air information (i.e., atmospheric pressure, temperature and humidity) from weather balloons sent up into the atmosphere (twice a day from each of the 122 forecast offices) to observe current atmospheric conditions. A wind profiler serves the same purpose by giving three-dimensional pictures of the winds and their patterns. These observations are then put into the computer models to make a prediction.

Hurricane shaped, tornado-producing supercell over Duplin, N.C. on April 16, 1999. Research Leading to Better Forecasts
Perhaps one of the best examples of the successful advances made in tornado forecasting technologies are radars developed by NOAA’s NSSL and used by the NWS:

Doppler Radar: Nearly 30 years ago, NSSL was a major participant in the development of Doppler technology that became the heart of the WSR-88D radar, commonly known as NEXRAD. The deployment of a system of 121 NEXRAD radars across the United States became a cornerstone of the modernization of the NOAA National Weather Service. Today there is an entire NEXRAD Network, which consists of system of 158 Doppler radars deployed across the United States and around the world.

The organization that led the development of Doppler weather radar is working to make it better. NSSL is working on polarimetric technology, an improvement that can be added to current Doppler technology and will soon test a completely new type of radar, called phased array. These new technologies are expected to lead to better forecasts and improved tornado (and other severe weather) warnings in the future:

Dual Polarized Radar: This spring, the NWS Norman Forecast Office will again test new radar technology being developed by NSSL. Specifically, the new dual-polarization radar uses two (i.e., horizontal and vertical) pulses instead of one (i.e., horizontal – such as on the current WSR-88D technology), providing more information for forecasters to better predict tornadoes and other severe weather. Polarimetric radars gather more information by transmitting radio wave pulses that have both horizontal and vertical orientations. The horizontal pulses give a measure of the horizontal dimension of cloud particles (cloud water and cloud ice) and precipitation particles (snow, ice pellets, hail, and rain), while the vertical pulses give a measure of the vertical dimension. Since the power returned to the radar is a complicated function of each particle's size, shape and ice density, the information will permit a detailed mapping of cloud composition. This information can be incorporated into short term computer models, leading to better forecasts. Researchers have been developing dual polarization radar for more than 20 years and expect the technology to be available for installation into the national radar network in five to 10 years. Polarimetric technology could be added to the current WSR-88D Doppler weather radars used by the NOAA National Weather Service throughout the nation.
Phased Array Radar: Phased-array radar technology, currently used to support tactical operations aboard Navy ships, is being adapted for weather detection. Development of this state-of-the-art radar technology led by NOAA may help forecasters provide earlier warnings for tornadoes and other hazardous weather. By this fall, a National Weather Radar Testbed will be established at NOAA's NSSL in Norman, Okla., providing the meteorological research community with the first phased-array radar facility available on a full-time basis. The project — from research and development to technology transfer and deployment throughout the United States — is expected to take 10 to 15 years with an initial cost of approximately $26 million for the Norman facility. Participants with the NSSL include the NOAA National Weather Service, Lockheed Martin, U.S. Navy, University of Oklahoma's School of Meteorology and College of Engineering, Federal Aviation Administration, Oklahoma State Regents for Higher Education and Basic Commerce and Industries, Inc. Phased-array radar uses electronically controlled beams. This reduces the scan time of severe weather from five to six minutes for current radar technology to only one minute, producing fast updates of data, and thereby potentially increasing the average lead time for tornado warnings. It will also be able to re-scan areas of severe weather very quickly, potentially increasing forecasters' warning lead times as storms rapidly transition to more severe levels. The new system will also be able to scan the atmosphere with more detail at lower elevations than current radars allow and gather storm information not currently available (such as rapid changes in wind fields) to provide more thorough understanding of storm evolution. Researchers and forecasters can then improve conceptual storm models and use that knowledge to evaluate and improve storm scale computer models. The data also will be used to initialize computer models and improve forecasts. Early tests of the phased array radar system show the technology has the potential to vastly improve upon the capabilities of the national NEXRAD radar network for all weather radar applications.

Models
As computers have become more sophisticated, the weather models used by forecasters have improved. These models are used to assist meteorologists in weather prediction. Forecasters rely on models to give them clues as to what the prediction will most likely be. However, the forecasters themselves must make the final decision. The forecasters analyze and interpret the information provided by the model to get a more accurate prediction.

“Deterministic” forecasting is the current mode of numerical weather prediction. This type of forecasting is quickly becoming outdated because it gives forecasters only a narrow prediction of the weather. They look at one forecast, which gives only one answer. The future of modeling is moving towards “probabilistic” forecasting, which provides a wide range of possibilities. “Ensemble forecasts” are one example of this type of forecasting. They are a group of numerical forecasts using 20 different models that are all slightly different. They include a variety of all the different members in the forecasting process that help lead to a consensus. NOAA researchers are currently generating ensemble numerical forecasts and plan to integrate them into operations in the future.

Other Sources of Tornado Information
Other information sources that have contributed to advanced tornado forecasts and warnings include NOAA Weather Radio, the Cooperative Weather Observer Network and Storm Spotters:

NOAA Weather Radio: Another key life saving, technological advancement spearheaded by the NWS during the past century is NOAA Weather Radio. This device, developed in the mid-1950s, gives Americans up-to-the-minute weather warnings and information 24 hours-a-day (from local forecast offices) and can be the difference between life and death. Weather warnings don't mean anything if they aren't received by those in harm's way. The NOAA National Weather Service broadcasts public life saving information during severe weather events (and other hazardous situations) on the NOAA Weather Radio network. NOAA Weather Radios with advanced digital technology called Specific Area Message Encoding (SAME) — and battery back-up system — can provide early warning of severe weather in the immediate area, especially during th night, alerting residents to turn to commercial televisions and radios for more information. Specifically, SAME technology allows the NOAA Weather Radio to receive a tone alarm signal, triggering a built-in alarm to sound and the radio to turn itself on, providing listeners with severe weather announcements for the county where they live. NOAA weather radios with SAME technology is the surest way to protect your family. NOAA encourages everyone to equip their homes, schools, businesses and public places with this life saving device, which should eventually become as common as smoke detectors.
Cooperative Weather Observer Network and Skywarn — Volunteers Making A Difference: Trained community volunteers enhance weather service operations. Cooperative observers collect weather data that becomes part of the nation's climate records and storm spotters provide the NOAA National Weather Service with visual confirmation of severe weather events:
- One mainstay in weather observation — not linked to technology — but as crucial to the NWS today as it was 100 years ago, is the Cooperative Weather Observer Program. The program, a network of more than 11,000 weather enthusiasts scattered across the country, provides crucial data to the NWS, and that data becomes part of U.S. weather history when it is archived at the NOAA National Climatic Data Center in Asheville, N.C. Cooperative observers measure precipitation, air and water temperatures, wind speed, barometric pressure and send the information to the NWS. In many cases, being a cooperative weather observer is a time-honored, family tradition, passed down through several generations.
- Skywarn is a NWS program of trained volunteer severe weather spotters. Skywarn volunteers support their local community and government by providing the NWS with timely and accurate confirmation of severe weather events. Reports from the spotters inform communities how they should respond when severe weather strikes. A majority of storm spotters are licensed amateur radio operators, who are trained by local NWS forecast offices on how to spot severe weather, help save lives by providing updated information on the location and track of the tornadoes and other dangerous conditions.

By working together, NOAA Research and the NWS have made significant advances in both tornado research and forecasting over the last century. This, together with effective local emergency preparedness plans and education that improves the public’s response during a tornado, has and will continue to save countless lives each year.

Relevant Web Sites
NOAA Tornado Page

NOAA National Weather Service

Tornado Forecasting

Tornado Safety

NOAA Research

NOAA's Storm Prediction Center

Next Generation Weather Radar system (NEXRAD)

NOAA's National Severe Storms Laboratory

Verification of the Origin of Tornadoes Experiment (VORTEX)

NOAA’s Storm Prediction Center

National Centers for Environmental Prediction

NOAA Satellite Page