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About the SPC

SPC Mission

The Storm Prediction Center exists solely to protect life and property of the American people through the issuance of timely and accurate watch and forecast products dealing with tornadoes, wildfires and other hazardous mesoscale weather phenomena.

SPC Vision

A team of world-class Applied Meteorologists, Computer Scientists, and Administrative Professionals that works to protect the American people from hazardous weather. This is accomplished by the use of state of the art science and technology to issue timely and accurate watch and forecast products for high-impact mesoscale weather including tornadoes, severe thunderstorms, wildfires, hazardous winter weather, and excessive rainfall.


The Storm Prediction Center (SPC) is part of the National Weather Service (NWS) and the National Centers for Environmental Prediction (NCEP). Our mission is to provide timely and accurate forecasts and watches for severe thunderstorms and tornadoes over the contiguous United States. The SPC also monitors heavy rain, heavy snow, and fire weather events across the U.S. and issues specific products for those hazards. We use the most advanced technology and scientific methods available to achieve this goal. If you are interested in the history of the SPC we have a set of pages that document much of the history of the SPC.

The SPC uses its suite of products to relay forecasts of organized severe weather as much as three days ahead of time, and continually refines the forecast up until the event has concluded. All products issued by the Storm Prediction Center are available on the World Wide Web. Our products are commonly used by local National Weather Service offices, emergency managers, TV and radio meteorologists, private weather forecasting companies, the aviation industry, storm spotters, agriculture, educational institutions and many other groups. A detailed description of all of the SPC products is available here.

Our very specialized mission requires meteorologists with a high level of expertise in convective storm forecasting, as well as excessive precipitation, winter weather, and conditions leading to high fire dangers. The SPC staff also is active in scientific research into severe and dangerous weather. All SPC forecasters have at least a Bachelor of Science degree in atmospheric science, and several have done graduate-level studies or hold a Master of Science degree. Most of the forecasters at the center have at least 5 years of specialized experience, with our more veteran forecasters having over 20 years of severe storm forecasting wisdom. We have participated in several major scientific experiments and field programs in recent years, including the V.O.R.T.EX. project. The SPC is located in Norman, Oklahoma, home of the National Severe Storms Laboratory, University of Oklahoma School of Meteorology and other weather centers. Our co-location with these groups should yield even greater scientific opportunities in the future. Several SPC meteorologists make severe storms their hobby as well -- being heavily involved with storm spotting and storm chasing on their own time.

Lead Forecasters

The lead forecaster serves as the "team leader," overseeing duties among other forecasters on shift and making sure each product issued is of the highest quality possible. This is so important that all products and bulletins from SPC are proofread by at least two pairs of eyes before they go out, one of which is usually the lead forecaster. The lead forecaster's job is very complex. He or she must be intimately familiar with every aspect of SPC operations, every type of forecast we issue, and a myriad of computers we use to do the job. The stress level of this job can be quite high on active severe weather days, with the lead forecaster having to closely monitor several areas of the country for impending thunderstorm development. A high level of situational awareness is required in this position.

The main operational duty of the lead forecaster is to issue Tornado and Severe Thunderstorm Watches as necessary. This involves a diligent national weather watch -- monitoring current and forecast weather all over the country for conditions that lead to violent thunderstorms. The lead forecaster must coordinate with numerous local NWS offices in the threat areas, and ensure that the watch process works smoothly. SPC watches alert the public, local NWS offices, emergency managers and storm spotters of the threat of severe thunderstorms and/or tornadoes during the next several hours, covering parts of one or more states. Besides alerting the general public to the threat for severe storms, these watches activate storm spotter networks that protect the public through their efforts.

The lead forecaster also composes Public Severe Weather Outlooks (PWOs) when major severe weather outbreaks threaten, and provides direct assistance and guidance in the preparation of all other forecasts at SPC.

Mesoscale Forecasters

Mesoscale forecasters specialize in forecasting dangerous weather on the "mesoscale," which comprises a time frame of up to 6 hours and an area typically 1/2 the size of Iowa (approx. 35000 sq. mi.). This involves extensive knowledge of weather processes that lead to severe thunderstorms, tornadoes, heavy rain, hazardous winter weather, and fire weather. This person's primary responsibility is to provide short term guidance on the formation and evolution of severe thunderstorms, tornadoes, heavy rain, and winter weather events.

Mesoscale forecasters compose concise short-term guidance messages called Mesoscale Discussions (MDs) that address areas of current or expected hazardous weather. The mesoscale forecaster also writes Status Reports for every severe weather watch in effect, at the top of the hour during the watch. Status Reports are guidance products which indicate where the severe weather threat persists within a given watch. They also discuss watch expiration and cancellation when needed.

Outlook Forecasters

The outlook forecaster prepares forecasts of thunderstorm activity across the continguous United States -- both severe and non-severe. The Day-1 Outlooks pertain to today's threat, while the Day-2 Outlooks pertain to tomorrow. This involves very detailed analysis of recent and current weather data and weather trends, followed by intensive examination of computer forecast models. Due to the large amount of weather data available in most cases, and the complexity of severe weather forecasting, many hours of work often go into the preparation of an outlook.

Day-1 and Day-2 outlooks are very important forecast guidance for local National Weather Service offices, often assisting in staffing decisions and storm spotter preparedness activities for the day (or night). They describe where severe weather is possible, when it may occur, why, how intense it might be, and depict the risk areas graphically.

Scientific Research at the Storm Prediction Center

Many SPC forecasters and support staff are heavily involved in scientific research into severe and hazardous weather. This involves conducting applied research and writing technical papers, developing training materials, giving seminars and other presentations locally and nationwide, attending scientific conferences, and participating in weather experiments. For example, SPC forecasters participated in the V.O.R.T.EX. project (1994-95), the largest and most intensive field program ever undertaken in an effort to understand tornadoes and the conditions that produce them.

Now that the SPC is in Norman, along with the National Severe Storms Laboratory, University of Oklahoma School of Meteorology and other members of the Oklahoma Weather Center, many more scientific opportunities and discoveries await from our interaction and cooperation.

Science Support

SPC's Science Support Branch maintains an extensive array of computer hardware and software, develops new software in support of forecast operations, and keeps the science-forecasting connection strong. Within Science Support, the Science and Operations Officer (SOO) is in charge of in-house meteorology training and integrating the latest atmospheric science discoveries into SPC forecasting. The SOO also oversees all SPC research projects and scientific publications.

Science Support also includes visiting scientists on occasion, as well as contract staff who deal with various types of computer programming, numerical modeling of the atmosphere, and network maintenance.

SPC Administration

The Administrative Staff oversees all SPC functions, beginning with the Director, who reports directly to the head of the National Centers for Environmental Prediction, SPC's parent agency. The Director is active in administrative areas, diversity, EEO, broadcast and print media relations, NWS outreach both internal and external, strategic planning, tactical planning, resource management, and severe reports data base management. The Warning Coordination Meteorologist serves as the SPC's point of contact for NWS field offices, emergency managers, private sector meteorologists and broadcast and print media. The Administrative Officer has a wide variety of managerial responsibilities, ranging from human resource, diversity, budgeting, acquisitions, tours, broadcast media scheduling, and International activities. The Administrative Assistant supports a wide variety of administrative activities and is the SPC's travel coordinator. The Operations Branch Chief and Science Support Branch Chief direct daily supervisory/ management duties of forecasters and support staff, respectively. A complete listing of current SPC staff is available here.

The Severe Storms Forecast Process:

Outlook to Mesoscale Discussion to Watch to Warning

SPC forecasters have a huge variety of tools at their disposal. Foremost is their formal training and experience in severe storms forecasting, which is unique to SPC. Past and current weather observations allow them to closely monitor changes in the atmosphere that lead to severe and hazardous weather. These observations come from satellite imagery, radars, surface weather stations, weather balloon soundings, wind profilers, lightning detection network, and information from local NWS offices. They also use such tools to assess how well the computer models are doing; then they use this knowledge to judge how reliable the models are for forecast purposes.

The severe weather forecast process at SPC begins with the Convective Outlook, which is a forecast of where both severe and non-severe thunderstorms are expected to occur around the country. Areas of possible severe thunderstorms are labeled "SLGT" (slight risk), "MDT" (moderate risk), or "HIGH" (high risk), depending upon the coverage and intensity of expected severe thunderstorms in a region. Many NWS offices use the Outlook to make emergency staffing decisions before severe weather begins.

As time progresses, a severe weather threat often becomes better defined over an area smaller than the Outlook, both in space and time. Mesoscale Discussions (MDs) are often needed to describe an evolving severe weather threat, and also to advise of possible watch issuance. [MDs are also issued for weather hazards that don't necessarily involve severe thunderstorms, including excessive rain, heavy snow and general thunderstorm trends.] Meteorological reasoning in MDs helps forecasters at local NWS offices to understand causes and prepare for the types of severe weather expected.

If development of severe thunderstorms is imminent, or likely to occur in the next several hours, the next step is a Severe Thunderstorm or Tornado Watch. Such watches alert the public, aviators and local NWS offices that environmental conditions have become favorable for the development of severe storms or tornadoes. Local storm spotter networks activate; and forecasters in the threat area closely monitor radar imagery and spotter reports to issue the appropriate severe thunderstorm and tornado warnings.

When severe hail (at least 3/4-inch diameter), damaging winds (at least 50 knots or 58 mph) or a tornado appear imminent, local NWS offices will issue a Severe Thunderstorm Warning or Tornado Warning as appropriate. The warning rapidly disseminated over NOAA Weather radio, commercial radio and TV stations and news wires, so that people in the warning area can find safe shelter to take cover from the storm.

[We also have a detailed explanation of Outlooks, MCDs, Watches and all other SPC products, available here.]

See also:
History of the SPC
Description of the SPC products

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NOAA / National Weather Service
National Centers for Environmental Prediction
Storm Prediction Center
120 David L. Boren Blvd.
Norman, OK 73072 U.S.A.
Page last modified: February 12, 2010
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