1936-1949
        1950-1959
        1960-1969
        1970-1984
        1985-2004

        Tornado case study pages by National Weather Service Forecast Areas

        As the following pages are updated, the above pages that are based on a range of years will gradually become obselete.  I am
        growing weary of constantly updating both.

     
        Saint Louis      
        Norman           
        Lubbock
        Amarillo
        Dodge City
        Cheyenne
        North Platte 
        Topeka    
        Boulder
        Wichita      
        Goodland
        Pueblo
        Albuquerque 
        Hastings
        Tulsa     
        Des Moines        
        Omaha    
        Minneapolis  
        Grand Forks
        Birmingham and Huntsville
         

     
        The goal is to provide an archive of surface/upper air charts and soundings for many United States tornado events. The data were
        plotted using digital atmosphere and then hand analyzed using Microsoft Paint. Just click on the date to get event details.
        Tornado paths and hail occurrences are plotted using SeverePlot v2.0 by John Hart of the Storm Prediction Center. Most of
        the details were obtained from the book 'Significant Tornadoes' by Tom Grazulis. This book is a fantastic resource for tornado
        enthusiasts. In the near future I plan to include plots of CAPE. For tornado cases, I prefer surface based CAPE because there is no
        way of knowing the vertical distribution of moisture in the boundary layer without a dense sounding network. Digital Atmosphere will
        soon be able to calculate CAPE fields.

        Great effort was taken to utilize all available data for these plots. This is not an automated process. The surface data on the surface
        charts below were coded manually in METAR format by the author of this webpage. This is really the only way to get a good handle
        on the severe weather environment. Recently, I have obtained surface date(1978-current) on cd from weathergrapics.
        This makes the process much faster since I don't have to code the metars by hand. A few observations were missing from this
        database so these were still coded by hand.

        CAPE varies greatly in time and space and using only the 1st order stations does not suffice  For example, there are no 1st order
        stations in eastern CO. A narrow CAPE axis in the traditional upslope corridor from southwest NE into northeast Colorado and
        the southern NE panhandle will never be sampled using only the 1st order stations. Surface data from the
        High Plains Regional Climate Center, University of Nebraska, Lincoln and CoAGMET data were used for some of the post
        1980 cases in the plains. The surface winds are in knots at most stations after 1955 and mainly in mph before 1955.

        I am making an effort to generate approximate soundings for some cases. This is fairly easy in summer and for cases where data
        are plentiful. The task becomes nearly impossible in data void regions and in winter when CAPE changes rapidly in time
        and space. Unfortunately the placement of weather observation sites is completely tied to aviation.

        Tornadoes have less to hit on the high plains and front range, and they generally move slower(thus have a shorter path length).
        They generally occur during daylight hours with no trees to block visual sighting. Higher cloud bases and flat terrain also help in the
        sighting of these tornadoes.The population density is very low on the high plains. Any humans in the way of these beasts generally
        have time to get out of the way. Therefore, tornadoes in this region will hit few structures and kill very few people. This does not mean
        these are weaker tornadoes. In fact, some tornadoes that are rated F0 to F2 above 3000ft would do F3 to F5 damage when
        moving 45-60 mph across Mississippi at 2am. 

        I have begun approximating instability for the cases below. While surface based CAPE is used widely these days, calculating CAPE
        from surface and upper air data can be a very labor intensive process. Until the process for computing CAPE becomes automated
        using digital atmosphere , I will approximate instability using the surface based lifted index. For stations above 5000ft., I may use
        the 400mb lifted index. I do not like using mean layer instability for surface based convection. While mean layer LI may be more
        realistic, I would rather stick with values that we know are correct using surface data. We really have no idea what the t/td profiles
        are above the surface. In well mixed situations, the pot. temp and mixing ratios are often conserved in the boundary layer, so using
        mean layer LI wouldn't really do any good anyway. The low level vertical distribution of moisture varies greatly in time and space.
        In case you are skeptical, just study the August 6, 1962 soundings across the plains from 12 UTC to 00 UTC. Moisture generally
        pools in areas of convergence where storms often initiate. Using soundings 50-100 km or more away would be very misleading.
        Good proximity soundings are hard to come by, especially in the cool season when theta-e varies greatly in time and space.
        In most cases, many soundings were considered, along with the appropriate surface data and elevation to calculate instability.
        In other words, surface and upper air data were judiciously utilized to approximate instability.

        The technique I used to approximate the lifted index without the virtual temperature correction is very simple. I took full advantage
        of surface observations in the inflow of the tornadic activity just prior or during the time of the tornadoes. I looked up the station
        pressure on the observation forms, as well as the T/TD. Then I approximated the 500mb temperature on the 500mb chart using the
        morning and evening data. Then I found a sounding on awips that had nearly the same surface pressure(station pressure). I modified
        the surface T/TD and 500mb temperature and found the lifted index.