Pertinent Geographic Information Systems (GIS) Data
from the April 27th, 2011 Outbreak
April 27, 2011 Event Overview

Currently on an experimental basis, the National Weather Service in Birmingham will be offering GIS data from storm surveys following severe weather events that unfold across central Alabama.  These data offer survey information from tornado tracks that are found by damage assessment teams in the field.  The links below contain information for all 62 tornadoes that have been surveyed across the State of Alabama that formed during the morning and afternoon of April 27, 2011.  Most information was produced and extracted from the National Weather Service Damage Assessment Toolkit, which has been developed by National Weather Service Meteorologists to modernize storm survey information into a geospatial format for the general public and GIS analysts.  The information can be passed along to decision makers and the emergency management community after storm surveys have been completed.  The Damage Survey Interface will continue to be devloped and improved, and hopefully implemented throughout the agency.

ESRI Shapefiles:       

All Tornado Paths - (Updated 8/27/11) Zipped folder contains polygon shapefiles of individual tornado tracks and estimated damage swaths, as well as an all inclusive shapefile that has all path information merged together.  Shapefile projections are in Universal Transverse Mercator Zone 16N.

All Survey Points(Updated 8/27/11) Zipped folder contains point shapefile locations within specific tornado paths that include detailed survey information gathered from assessment teams in the field.  The attribute information includes:  Event Date, Survey Date, Damage Indicator, Degree of Damage, EF-Rating at the point location, Wind Speed, Comments from the survey team regarding specific damage information, and the Tornado associated with the survey point. Shapefile projections are in Universal Transverse Mercator Zone 16N.

All Tornado Tracks - (Posted 8/28/11) Zipped folder contains line shapefiles of all 62 tornado tracks across the State of Alabama.  Attribute information includes:  Tornado Name, EF-Scale, Peak Wind, Counties affected, Start Time, Beginning and Ending Latitudes and Longitudes, End Time, Maximum width in miles and yards, Order Number of the tornado segement, and Tornado Number according to the statewide tornado map.  Shapefile projections are in Universal Transverse Mercator Zone 16N.

Attention GIS Analysts Using ArcGISPlease view the metadata within ArcCatalog to view a complete description of shapefile information.

 Google Earth KMZ Files:     

Tornado Survey Information KMZ (Updated 8/28/11) Google Earth KMZ contains all the detailed storm survey information gathered from the historic outbreak for the 29 tornadoes in the Birmingham County Warning Area.  In select locations, damage photographs taken by assessment teams can also be viewed.  Be advised that this information is still deemed as experimental.  The information was extracted from the National Weather Service Damage Assessment Toolkit.

Alabama EMA Map Books: 

The following map books, courtesy of the Alabama Emergency Management Agency, analyze the most affected areas from the April 27, 2011 tornado outbreak.  Alabama Civil Air Patrol overflight imagery are used along with GIS roadway shapefiles overlaid on top of the imagery.  The maps below were compiled by the Alabama State Oil and Gas Board, Geological Survey of Alabama, and the University of Alabama.

Interactive Map - Tornado Paths and Survey Points:

The map below presents an interactive view of tornado paths and survey locations collected by damage assessment teams in the field from the April 27, 2011 Historic Tornado Outbreak.  Many of these same points can be downloaded using the links for the Paths and Survey Point Shapefiles above.  To view information from the survey points, zoom in to the specific point of interest and click on the point.  A pop-up box will appear with specific survey information.  Damage photographs, if they are available, can be viewed by scrolling to the bottom of the pop-up.  Click on the image for the full resolution version in a separate tab.  If several features appear within a close proximity to one another, look for the "Next Feature" button (>) on the top right of the pop-up to view each feature.  To zoom in and out, use your mouse wheel or use the plus and minus buttons in the top left corner of the map. Once again, these data are experimental.  The map below can also be viewed on by searching "Tornado" and clicking on "April 27, 2011 NWS BMX Interactive Survey Map."

View Larger Map

Statewide Geospatial Information: (Updated 8/28/11)

The April 27, 2011 Tornado Outbreak had far reaching effects across the State of Alabama.  With assisstance from the National Weather Service in Huntsville, National Weather Service in Mobile, and the Alabama Emergency Management Agency, a detailed statewide tornado map was created.  The map below depicts the tornado tracks starting in the morning of April 27th and ending during the evening hours.  Each number below represents the start time of each tornado in chronological order, beginning on the morning of April 27th.

62 tornadoes have been confirmed across the entire state.
  By clicking on the numbers below, you will be taken to detailed survey information regarding the tornado of interest.

 *Tornadoes #2, #41, and #54 contain asterisks due to the fact they are labeled as EF-2 (#2), EF-5 (#41), and EF-4 (#54).  Those are the maxium ratings of those tornadoes when they were on the ground in Mississippi before they moved into Alabama. Tornado #2 was an EF-1 in Alabama, #41 was an EF-3 in Alabama, and tornado #54 was an EF-3 in Choctaw County and an EF-2 in Marengo and Perry Counties.

Statewide Tornado Statistics:

Total Number of Tornadoes:  62
Total Mileage of All Tornadoes Across Alabama: 1202.47 Miles

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