The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC).
Headquartered at the National Weather Center in Norman, Oklahoma, the Storm Prediction Center is tasked with forecasting the risk of severe thunderstorms and tornadoes in the contiguous United States. It issues convective outlooks, mesoscale discussions, and watches as a part of this process. Convective outlooks are issued for the following eight days (issued separately for Day 1, Day 2, Day 3, and Days 4–8), and detail the risk of severe thunderstorms and tornadoes during the given forecast period, although tornado, hail and wind details are only available for Days 1 and 2. Day 3 uses a probabilistic scale from a Marginal to Moderate risk (A Day 3 High risk cannot be issued), while Days 4–8 use a probabilistic scale determining the probability for a severe weather event in percentage categories (15%/yellow and 30%/orange).
Mesoscale discussions are issued to provide information on certain individual regions where severe weather is becoming a threat and states whether a watch is likely and details thereof, particularly concerning conditions conducive for the development of severe thunderstorms in the short term, as well as situations of isolated severe weather when watches are not necessary. Watches are issued when atmospheric conditions favor the development of severe weather. Once a storm/tornado is imminent or occurring (such as via weather spotters, radar, river gages, etc), a warning will be issued, and it usually precedes the onset of severe weather by one hour, although this sometimes varies depending on certain atmospheric conditions that may inhibit or accelerate convective development.
The agency is also responsible for forecasting fire weather (indicating conditions that are favorable for wildfires) in the contiguous U.S., issuing fire weather outlooks for Days 1, 2, and 3–8, which detail areas with various levels of risk for fire conditions (such as fire levels and fire alerts).
History The Storm Prediction Center began in 1952 as SELS (Severe Local Storms Unit), as part of the U.S. Weather Bureau in Washington, D.C. In 1954, the unit moved its forecast operations to Kansas City, Missouri. SELS began issuing convective outlooks for predicted thunderstorm activity in 1955, and began issuing radar summaries in three-hour intervals in 1960; with the increased duties of compiling and disseminating radar summaries, this unit became the National Severe Storms Forecast Center (NSSFC) in 1966, remaining headquartered in Kansas City.
In 1968, the National Severe Storms Forecast Center began issuing status reports on weather watches; the agency then made its first computerized data transmission in 1971. On April 2, 1982, the agency issued its first "Particularly Dangerous Situation" watch, which indicates the imminent threat of a major severe weather event over the watch's timespan. In 1986, the NSSFC introduced two new forecast products: the Day 2 Convective Outlook (which included outlined areas having a risk for severe thunderstorms the following day) and the Mesoscale Discussion (a short-term forecast outlining specific areas under threat for more imminent severe thunderstorm development).
The National Severe Storms Forecast Center was renamed the Storm Prediction Center in October 1995, upon the creation of the NOAA-NWS National Centers for Environmental Prediction (NCEP), of which it was a part. In January 1997, the Storm Prediction Center completed a relocation to Norman, Oklahoma. At that time, the center was located near the Max Westheimer Airport (now the University of Oklahoma Westheimer Airport), on the "North Base" property of the University of Oklahoma, sharing space with the National Severe Storms Laboratory. (This building was across from the local National Weather Service Weather Forecast Office which, in addition to disseminating forecasts, oversees the issuance of weather warnings and advisories for the western two-thirds of Oklahoma and western portions of North Texas, and issues outline and status updates for SPC-issued severe thunderstorm and tornado watches that include areas served by the Norman office). In 1998, the Storm Prediction Center began issuing the National Fire Weather Outlook to provide forecasts for areas potentially susceptible to the development and spread of wildfires based on certain meteorological factors. The Day 3 Convective Outlook (which is similar in format to the Day 2 forecast) was first issued on an experimental basis in 2000, and became a routine product in 2001.
In 2006, the Storm Prediction Center, National Severe Storms Laboratory and National Weather Service Norman Forecast Office moved their respective operations into the newly constructed National Weather Center, on the south edge of the University of Oklahoma Norman campus. Since the agency's relocation to Norman, the 557th Weather Wing at Offutt Air Force Base would assume control of issuing the Storm Prediction Center's severe weather products in the event that the SPC is no longer able to issue them in the event of an outage (such as a computer system failure or building-wide power disruption) or emergency (such as an approaching strong tornadic circulation or tornado on the ground) affecting the Norman campus; on April 1, 2009, the SPC reassigned responsibilities for issuing the center's products in such situations to the 15th Operational Weather Squadron based out of Scott Air Force Base.
On March 17, 2025, ABC News, reporting from the word of an anonymous NOAA spokesperson, stated the Storm Prediction Center was set to be closed by the Department of Government Efficiency (DOGE), a branch of the U.S. government created by President Donald Trump to eliminate government waste. DOGE had announced other NOAA office terminations during March 2025. ABC News also reported the SPC office was listed on DOGE's website, however, as of March 18, DOGE's website says its most recent update was on March 11.
Brief history timeline
1948: Following Weather Bureau (WB) researchers' work by on a 20 March tornado at Tinker AFB, two officers (Fawbush and Miller) successfully predict another one five days later on 25 March at same base, given responsibility for AF tornado predictions. 1951: Severe Weather Warning Center (SWWC) established as an Air Weather Service unit, headed by Fawbush and Miller. 1952: WB establishes its own Weather Bureau-Army-Navy (WBAN) Analysis Center in Washington in March as a trial unit, made permanent on 21 May as the Weather Bureau Severe Weather Unit (SWU). 1953: SWU renamed Severe Local Storm (SELS) Warning Center on 17 June. 1954: SELS relocates from the WBAN Center in Washington to the WB's District Forecast Office (DFO) in downtown Kansas City in September. 1955: National Severe Storms Project (NSSP) formed SELS' as research component. 1958: SELS assumes authority for all public severe weather forecasts. 1962: Some from NSSP move to Norman's Weather Radar Laboratory to work with a new Weather Surveillance Radar-1957 (WSR-57). 1964: Remainder of NSSP moves to Norman and is reorganized as National Severe Storms Laboratory (NSSL). 1965: Environmental Science Services Administration (ESSA) formed, and entire WB office (SELS and DFO) in Kansas City renamed National Severe Storms Forecast Center (NSSFC). 1976: Techniques Development Unit (TDU) established in April to provide software development and evaluate forecast methods. 1995: NSSFC renamed Storm Prediction Center (SPC) in October. 1997: SPC moves from Kansas City to Norman. 2006: SPC moves a few miles south to the National Weather Center (NWC) on the University of Oklahoma Research Campus. 2023: On February 15, 2023, Meteorologist Elizabeth Leitman becomes the first woman at the SPC to issue a convective weather watch.
Overview The Storm Prediction Center is responsible for forecasting the risk of severe weather caused by severe thunderstorms, specifically those producing tornadoes, hail of in diameter or larger, and/or winds of [50 knots] or greater. The agency also forecasts hazardous winter and fire weather conditions. It does so primarily by issuing convective outlooks, severe thunderstorm watches, tornado watches and mesoscale discussions.
There is a three-stage process in which the area, time period, and details of a severe weather forecast are refined from a broad-scale forecast of potential hazards to a more specific and detailed forecast of what hazards are expected, and where and in what time frame they are expected to occur. If warranted, forecasts will also increase in severity through this three-stage process.
The Storm Prediction Center employs a total of 43 personnel, including five lead forecasters, ten mesoscale/outlook forecasters, and seven assistant mesoscale forecasters. 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.
Convective outlooks
The Storm Prediction Center issues convective outlooks (AC), consisting of categorical and probabilistic forecasts describing the general threat of severe convective storms over the contiguous United States for the next six to 192 hours (Day 1 through Day 8). These outlooks are labeled and issued by day, and are issued up to five times per day.
The categorical levels of risks are TSTM (for Thunder Storm: light green shaded area – rendered as a brown line prior to April 2011 – indicating a risk for general thunderstorms), "MRGL" (for Marginal: darker green shaded area, indicating a very low but present risk of severe weather); "SLGT" (for Slight: yellow shaded area – previously rendered as a green line – indicating a slight risk of severe weather); "ENH" (for Enhanced: orange shaded area, which replaced the upper end of the SLGT category on October 22, 2014); "MDT" (for Moderate: red shaded area – previously rendered as a red line – indicating a moderate risk of severe weather); and "HIGH" (pink shaded area – previously a rendered as a fuchsia line – indicating a high risk of severe weather).
In April 2011, the SPC introduced a new graphical format for its categorical and probability outlooks, which included the shading of risk areas (with the colors corresponding to each category, as mentioned above, being changed as well) and population, county/parish/borough and interstate overlays. The new shaded maps also incorporated a revised color palette for the shaded probability categories in each outlook.
In 2013, the SPC incorporated a small table under the Convective Outlook's risk category map that indicates the total coverage area by square miles, the total estimated population affected and major cities included within a severe weather risk area.
Public severe weather outlooks (PWO) are issued when a significant or widespread outbreak is expected, especially for tornadoes. From November to March, it can also be issued for any threat of significant tornadoes in the nighttime hours, noting the lower awareness and greater danger of tornadoes at that time of year.
Operational risk levels