The following tutorial was designed to investigate the radar characteristics of the fatality-producing, tornadic storm in Hall/White County, Georgia (see map) that occurred between 1100 and 1200 Z on 20 March 1998. A Review of this event is useful to illustrate radar issues when observing a small storm with subtle signatures, a scenario commonly observed in environments with low CAPE. The main sections of this tutorial are the instructions, environmental data, environmental discussion, the radar viewer, and the summary.

When you are ready to review the environmental data, select the "Go to the Environmental Data" button. The environmental data section contains soundings, surface maps, satellite imagery and numerical model output from the RUC hourly initialization fields. Peruse the links provided and become familiar with the "big picture".

After reviewing the environmental data section, move down the page to the environmental discussion section. The environmental discussion section provides an overview of important features in the environment of this case. Links are provided in the overview to support description in the text. Upon finishing the environmental discussion section, click on the "Go to the Radar Data Viewer" button to begin analysis of the radar data.

When you click on the "Go to the Radar Data Viewer" button, a Java applet will appear along with a link to the "Instructions for OTB Image Viewer." Read the Image Viewer instructions, and load in the data. The radar viewer can take as little as two minutes or as long as twenty minutes to load all of the associated files. A break is recommended at this point.

After the data has been loaded, the radar viewer allows the user to peruse WSR-88D products in a static or animated manner. Images are available from the Peachtree City, Georgia radar (KFFC) for seven volume scans that cover the period prior to, during, and after tornadogenesis. Use the buttons along the top of the viewer to access one of the following radar products:

CREF - Composite Reflectivity
BREF1-4 - Base Reflectivity for elevation angles 1-4 (0.5°,1.5°,2.4°,3.4°)
SRM1-4 - Storm-Relative Velocity Map for elevation angles 1-4 (0.5°,1.5°,2.4°,3.4°)
VEL1 - 0.5° Base Velocity
VIL - Vertically Integrated Liquid
MESO - 88D Mesocyclone ID
BREF4P - Four-Panel Base Reflectivity from PUP
SRM4P - Four-Panel Storm-Relative Velocity Map from PUP with Mesocyclone ID Overlay.

In both four-panel images, the 0.5° panel is in the upper left, the l.5° panel is in the upper right, the 2.4° panel is in the lower left, and the 3.4° panel is in the lower right. Note that the four-panel images are of higher image resolution than most of the single-panel images due to the four-panel images being generated from the PUP and most of the single-panel images being generated in GEMPAK.

In addition to viewing WSR-88D products, the applet also provides the user with numerous questions about the event. The questions, which are all multiple choice, can be accessed by clicking on the question number menu at the bottom left-hand side of the viewer window. There is one question for each volume scan (questions #1-7) and then several questions that inquire about the overall event (questions #8-11). For each question, a question window pops open upon selecting a question number. To submit an answer, click on the appropriate answer circle, A-D. To exit the question and answer windows, click on the "OK" or "Cancel" buttons at the bottom of the windows. Upon completion of all eleven questions, click on the "Go to the Tutorial Summary" button to conclude the tutorial.

Other notes about the tutorial:

• Before proceeding with the rest of the tutorial, make sure that your screen resolution is set to 1024x768 and have at least a 16-bit color palette (at the Start button in the lower left corner of the screen, select Settings --> Control Panel --> Display --> Settings). Otherwise, you will have difficulty viewing the applet and other images in the tutorial.
• The applet will only run in recently-released versions of Internet Explorer 4.0 (or higher; IE4) or Netscape Navigator 4.5 (or higher). We recommend that, if you do not have one of the recently-released versions of these browsers to view the tutorial, you should download and install a newer version before continuing. You will also need to turn off any pop-up blocking software for the Radar Data Viewer to open.

Please send any questions

or comments to Mike Magsig: