Storm Prediction Center

The topic of the Storm Predication Center was suggested by one of our followers. In recognition of Hurricane Preparedness Week, we at want to raise awareness of the services provided by the Storm Prediction Center per the following:

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 for hazardous winter weather and fire weather events and issues specific products for those hazards. We use the most advanced technology and scientific methods available to achieve this goal.

What is Severe Weather?

The NWS defines a severe thunderstorm as any storm that produces one or more of the following elements:

  • A tornado.
  • Damaging winds or speeds of 58 mph (50 knots) or greater.
  • Hail 1 inch in diameter or larger.

The SPC further defines significant severe thunderstorms as any storm that produce one or more of the following elements:

  • A tornado that produces EF2 or greater damage.
  • Wind speeds of 75 mph (65 knots) or greater.
  • Hail 2 inch in diameter or larger.

Convective Outlooks

SPC issues Day 1, Day 2, and Day 3 Convective Outlooks that depict non-severe thunderstorm areas and severe thunderstorm threats across the contiguous United States, along with a text narrative. The categorical forecast specifies the level of the overall severe weather threat via numbers (e.g., 5), descriptive labeling (e.g., HIGH), and colors (e.g., magenta). The probabilistic forecast directly expresses the best estimate of a severe weather event occurring within 25 miles of a point. The text narrative begins with a listing of severe thunderstorm risk areas by state and/or geographic region. This is followed by a concise, plain-language summary of the type(s) of threat along with timing that is focused on the highest-risk areas. The rest of the outlook text is written in scientific language for sophisticated users. This technical discussion usually includes a synopsis section to provide a general overview of the weather pattern, emphasizing features that will influence the severe and general thunderstorm threats. Additional sections of the discussion are usually separated by geographic areas. Within these individual geographic areas, the text offers meteorological reasoning and justification for the type of coverage and intensity attendant to the severe weather threat.

SPC also issues a Day 4-8 Severe Weather Outlook that similarly depicts severe thunderstorm threats across the contiguous United States and contains a technical discussion.

Log onto Storm Predication Center for updated severe weather forecasts and outlooks. 

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