National Weather Service Training Center

How to Develop
A Severe Weather Climatology

Purpose of this Web Page | Sources of Climatological Information
Content of Local Climatological Data Base | Examples | Bibliography
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Purpose of this Web Page

The purpose of this web page is to provide a list of resources which can be used to develop a local severe weather climatology. A knowledge of this climatology can be used by local forecasters to become familiar with the range of possible atmospheric phenomena associated with current observations. Using climatology as a baseline, they can further investigate why various types of severe weather occur with greater (or lesser) frequency, at certain times of the day, or certain seasons of the year. A thorough knowledge of local climatology is a very important part of the overall forecast process.

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Sources of Climatological Information

A local/county warning area climatology of severe convective weather can be built from the sources listed below. The local severe weather focal point, WCM, or climatological focal point should investigate these sources and develop a local/CWA climatology that will satisfy the need described above.

  • CLIMO Program

    The CLIMO Program was written by Mike Vescio of the Storm Prediction Center (SPC) to obtain severe weather statistics for National Weather Service county warning areas (CWA). The program output is standardized and cannot be changed, but there is a wealth of information that can be used to build a local/CWA climatology. The output is in text format. The program is available from Mike Vescio. Contact him via NWS e-mail.

  • Storm Prediction Center Home Page

    The Storm Prediction Center maintains a historical archive on its Online Archives home page. Zipped raw data files for tornado occurrence, hail occurrence, and convective wind and wind damage can be downloaded and decoded using programs available on the archive page. These data can be used to create a local/CWA climatology for these severe weather phenomena.

  • SVRPLOT Program

    SVRPLOT is a software package for IBM-compatible PCs written by John Hart of SPC. This program analyzes and maps severe weather events from historical archive files. Program requirements and files are found on the SVRPLOT Home Page off the SPC Software page.

  • National Climatic Data Center

    Tornado statistics in graphical format can be obtained from the National Climatic Data Center (NCDC) Severe and Extreme Weather: Climatological Maps and Tables web page. NCDC can also provide raw data to any NWS office upon request and information from the publication "Storm Data" as well.

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    Content of Local Climatological Data Base

    Even though each WFO will likely shape their local climatological data base into a form that fits their needs, the elements listed below are recommended as the minimum content that the data base should contain:

  • For Tornadoes:

    1. Listing of all tornado data, by year
    2. Yearly totals by F-scale, path length, and path width
    3. Period of record totals by F-scale, path length, and path width
    4. Monthly distribution of the number of tornadoes, number of F2 or greater tornadoes, and number of killer tornadoes, for the period of record
    5. Hourly distribution of the number of tornadoes, number of F2 or greater tornadoes, and number of killer tornadoes, for the period of record
    6. Hourly distribution of the number of tornadoes, number of F2 or greater tornadoes, and number of killer tornadoes, for the period of record, by month


  • For Large Hail:

    1. Listing of all hail data, by year
    2. Yearly totals by category (0.75<1.75, 1.75<2.75, 2.75 or larger)
    3. Period of record totals by category
    4. Monthly distribution, by size category
    5. Hourly distribution, for the entire period of record
    6. Hourly distribution, for a given month


  • For Damaging Winds:

    1. Listing of all wind and wind damage data, by year
    2. Yearly totals, events and days
    3. Period of record totals, events and days
    4. Monthly distribution
    5. Hourly distribution, for the entire period of record
    6. Hourly distribution, for a given month

    • These statistics can be easily produced by the CLIMO program described above.

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    Examples

    Check the links below to see examples of web-based severe weather climatologies:

  • Lake Charles, Louisiana
  • Tornado Climatologies
  • Example Developed by the NWSTC

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    Bibliography

    The following is a list of existing climatology resources that may have application in your local/county warning area:

  • Bibliography

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    Last updated 6/09/98


    Unit 1 Description