The Storm Prediction Center maintains a high-achieving staff using innovative science
and technology to deliver timely and accurate watch and forecast products/information
dealing with tornadoes, severe thunderstorms, lightning, wildfires, and winter
weather for the United States to protect lives and property.
The trusted source for the prediction of tornadoes and other high-impact hazardous weather.
SPC national products and services for severe thunderstorms and tornadoes are an
essential source of information for the protection of life and property.
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 hazardous winter weather 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 eight days ahead of
time, and continually refines the forecast up until the event has
concluded. 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
Our very specialized mission requires meteorologists with a high level
of expertise in convective storm forecasting, 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. The SPC is located in Norman, Oklahoma at the
Weather Center, which is on the campus of the University of Oklahoma.
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.
Mesoscale forecasters specialize in forecasting dangerous weather on
the "mesoscale," which comprises a time frame of up to 6 hours and an
area typically about half the size of a standard U.S. state. This
involves extensive knowledge of weather processes that lead to severe
thunderstorms, tornadoes, and hazardous winter weather. This person's primary
responsibility is to provide short term guidance on the formation and evolution of severe thunderstorms,
tornadoes, and winter weather events.
Mesoscale forecasters compose concise short-term guidance messages called
(MDs) that address areas of current or expected hazardous weather.
The mesoscale forecaster also issues
Status Reports for every severe weather watch in effect, at the bottom
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.
The outlook forecasters prepare forecasts out to eight days for severe and non-severe
thunderstorms across the contiguous United States, as well as weather conditions favorable
for the spread and/or ignition of wildfires. The Day 1 Convective Outlook and the Day 1 Fire
Weather Outlook pertains to today's threat. The Day 2 Convective Outlook and the Day 2 Fire Weather
Outlook pertain to tomorrow. The Day 3 Convective Outlook pertains to the day after tomorrow. The
Day 4-8 Severe Weather Outlook and Day 3-8 Fire Weather Outlook provide extended forecast information
out to about a week in advance.
Each outlook involves detailed analysis of recent and current weather data, followed by intensive
examination of computer forecast models. Due to the large amount of weather data available in most
cases, and the complexity of high-impact weather forecasting, hours or work often go into the preparation
of an outlook.
The Convective and Fire Weather Outlooks are important forecast guidance for local NWS offices, often assiting in
staff decisions and storm spotter preparedness activities for the day (or night). They depict risk areas graphically,
and through text describe the what, when, and where, along with reasoning for why the convective or fire weather
hazard may occur.
Many SPC forecasters and support staff are heavily involved
in scientific research into severe and
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.
Now that the SPC is in Norman, along with the National Severe Storms Laboratory,
the University of Oklahoma School of Meteorology and other members of the National Weather Center, many more scientific
opportunities and discoveries await from our interaction and cooperation.
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.
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 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
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, 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 "MRGL" (marginal risk), "SLGT" (slight risk),
"ENH" (enhanced 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 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 1-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 and various mass and social media channels, so that people
in the warning area can find safe shelter to take cover from the storm.
The Fire Weather Forecast Process
SPC forecaster Ariel Cohen describes the SPC fire weather forecast process for a meteorology
class at the University of Oklahoma. You can view the YouTube video:
[We also have a detailed explanation of Outlooks, MCDs, Watches and
all other SPC products, available here.]
History of the SPC
Description of the SPC products