RadarLab Classic Usage Guide
Introduction
RadarLab is a weatherTAP feature which allows the user to have interactive control over weather graphic presentation. Using RadarLab, the user may select a background image which contains radar data, then select one or more "overlays" such as county boundaries or highways which is displayed over the base image. The user can zoom up to 5x and scroll around the zoomed image. Animations can be created by loading up to 20 frames of images. The user can single-step through animations, or control the playback speed. Overlays and zooms also apply to animations. An advanced filtering option is available and images may be automatically reloaded.
The RadarLab screen consists of a radar image, an overlay toggle section,
a storm attributes window, and various image controls.
Using RadarLab
When a RadarLab image is initially displayed, a base reflectivity image will be loaded and none of the overlays will be selected. Once the image has completely loaded, you may manipulate the image by turning on or off overlays or using the image controls.
Overlays
All available overlays will be listed at the top of the RadarLab window with checkboxes displayed beside the text. To enable an overlay, simply click on the checkbox (a check should then appear in the box) and the overlay will be drawn on the radar image. If the overlay has not previously been used, then a short delay will occur as the overlay is being downloaded. To turn off the overlay, simply click the check box (this time, the check should disappear in the box) and the overlay will be removed from the radar display. Note overlays work even if the image is animated, or zoomed.
Selecting a Background
When you initially display a RadarLab screen, the base reflectivity image from the radar you selected will be displayed. You may, however, choose another image type by clicking the appropriate option in the "Background Image" pane on the upper right hand portion of the RadarLab screen. Changing background images will cause the browser to reload the new data (which could take a few seconds) and redraw the overlays on the new image. Note that if you change backgrounds while an animation is playing, the animation will be stopped and the new image will not be animated. To restart the animation with the new background, simply press the "Play" button.
Zooming
You may zoom any image (animated or still) by pressing the "+" or "-" buttons found in the "Zoom Controls" pane. You may zoom from 1x (normal size) up to 5x (5 times normal size). You may scroll the zoomed image by using the arrow buttons, also located in the "Zoom Controls" pane. Overlays may be turned on or off while the image is zoomed. Animation can also be started even while zoomed. To return to normal size and re-center, simply click the "O" button located in the middle of the pan arrow buttons.
Animation
RadarLab allows the user to control many aspects of animation. All animation controls are contained within the "Animation" pane of the RadarLab display. To start an animation, simply press the "Play" button. The browser will begin loading the animation and you will see "Loading" appear in the browser status window. When all images have been loaded, the animation will begin to play. To temporarily pause the animation, press the "Pause" button (which was previously labeled "Play"). To completely stop the animation and return to a still frame image, press the "Stop" button..
Animation works by rapidly flipping pages (frames) of images. The frames are numbered starting at 0 for the most current frame up to a maximum of 20 frames in the past. The user may set the number of frames in the animation by changing the "# Frames" parameter (default is 10). When you play an animation, the browser simply starts with the highest numbered frame (oldest) and begins counting down to the zero frame (most current). You may step through the frames of a stopped animation one at a time by using the "<" and ">" buttons while the animation is paused. The "<" button will cause the browser to load an older (higher number) frame. The ">" button will cause the browser to load a newer (lower number) frame. The user may also control speed of the animation by manipulating the delay between frames. To increase the delay (slowing down the animation), press the "-" button next the "Play" button. To speed up the animation, press the "+" button.
You may change zoom factors, turn overlays on or off, or view the storm attribute window while an animation is running
Storm Attributes
Nexrad radar sites analyze data from each volume scan to identify storm cells. Each identified cell is assigned an alphanumeric identifier and certain attributes of that cell are tabulated. RadarLab allows the user to view the storm attributes table. RadarLab also provides the ability to graphically plot the storm cells along with a predicted track.
Storm tracks can be toggled on or off just like any other overlay by using the "Storm Tracks" toggle. When activated, storm tracks are plotted on top of the background image. The identified center of the cell is plotted as a centroid symbol with the cell identifier printed below. If a cell has been tracked for more than one volume scan, a "track" will be plotted showing the direction of cell movement. Marks along the track indicate predicted positions at 15 minute intervals up to 1 hour. Newly identified cells will have a centroid, but not a track since speed and direction has not yet been determined.
Storm tracks are calculated by examining wind speed and direction data from the storm attributes table. All of the data in the table may be viewed by clicking the "Storm Table" checkbox located in the Overlay Toggles section of the RadarLab screen. When selected, the storm attribute table will appear in a separate window. A detailed description of the various storm attributes is available.
In times of intense convective activity a large number of storm cells may be identified. When this occurs the storm track overlay tends to become very cluttered. The storm attribute window contains many options to allow the user to control which cells are plotted as well as how the cells are plotted. By default, when an image is loaded, tracks will be displayed for all cells. The "DISPTRK" value indicates whether or not the track for a particular cell should be plotted. The DISPTRK status for any particular cell can be toggled on or off by double-clicking on the cell in the list.
A number of options are available for quickly turning the DISPTRK status on and off based on different criteria.
Show All - Turns the DISPTRK status on for all cells in the current table
Show None - Turns the DISPTRK status off for all cells in the current table
MESO Only - Turns DISPTRK off for all cells, except those that have a MESO value other than "NONE"
TVS Only - Turns DISPTRK off for all cells, except those that have a TVS value other than "NONE"
Top 10 DBZ's - Causes the list to be sorted by max DBz. The top 10 cells with the highest DBz value are turned on.
Top 10 VIL's - Causes the list to be sorted by VIL. The top 10 cells with the highest VIL value are turned on.
The six buttons buttons normally operate only on the currently displayed frame. The user can force all frames to be acted on by clicking the "Apply to all frames" checkbox. The main RadarLab screen is normally not immediately updated when changes are made to the storm track display options. To force the main RadarLab screen to update, simply click the "Redraw" button. When activated, the "Auto-Reload" option will force the main screen to redraw automatically when any display option is changed. This may not always be desirable since it may take a long time when large animations are loaded.
The size and color of the storm tracks may be changed by using the "Size" and "Color" controls.
Image Controls
Image filteringRadarLab can be configured to filter certain reflectivity values on the radar display. This could be used to filter out weak echoes to reduce ground clutter, to filter out heavy echoes, or to isolate a particular weather phenomenon. To select which scale values should be filtered out, simply click the appropriate color in the vertical color scale located in the "Image Controls" section. An 'X' will appear inside the box to indicate that this color will be removed from the display if image filtering is enabled. To turn the color back on, simply click again in the box. The 'X' should disappear. To activate image filtering, configure the filter by removing the appropriate values then click the "Filter" checkbox. The filter will them be applied to the displayed still or animated image.
Optional Timestamp
The image timestamp can be displayed in the lower right-hand corner of the image. This is useful if the image is zoomed and the normal time stamp is out of view. To activate the option time stamp, simply click on the "Timestamp" checkbox.
Auto Refresh
RadarLab can be set to automatically reload a still image every 5 minutes. To activate this feature, simply click the the "Auto Refresh" checkbox. Animations may also be auto-reloaded, however, the auto-reload option will revert back to still images after 1 hour of reloading animations.
Cursor Data
RadarLab can provide information about the cursor location and reflectivity values. To activate this feature, click and hold the left mouse button over a location in the image. A window will be displayed giving the cursor position in latitude and longitude. The radar data value of the cursor location will be displayed. An arrow shaped pointer will also appear on the filter color selection tool indicating the color value of the pixel under the cursor.
Distance and Bearing Tool
A simple tool is provided for determining the distance and bearing between any two points. To use this feature, move the cursor to the first point and hold the right mouse button. Now drag the cursor around the screen. A window beside the cursor will indicate the direction and bearing from the first point to the cursor location.
Interrogate Mode
RadarLab can be used to query NWS stations for the latest observation data. To use this feature, turn on Interrogate mode by clicking the "Interrogate" checkbox located at the top of the RadarLab window. Once activated, the status line will indicate the interrogate mode is on and the cursor will change to a hand shape. To get observation data, simply click on the map. The station closest (geographically) to the location you clicked will be polled and the observation data will be displayed in a separate window. The location of the observation station will be indicated on the map by a green X and the station ID will also be printed. Interrogate mode can be used to gather as many observations as desired. Deactivate interrogate mode by u- checking the "Interrogate" checkbox.
MyRadarLab
A special feature called "MyRadarLab" is available to allow the user to create their own overlays. To display overlays (previously configured in the MyRadarLab configuration tool), simply check the "MyRadarLab" checkbox. If any of the user locations are located within frame of view of the currently displayed image, then they will be plotted on top of the radar image just like any other overlay.
Helpful Hints
RadarLab relies on Java technology to run. You must have a Java-enabled web browser and Java must be turned on to use RadarLab.
RadarLab is an advanced feature of weatherTAP which is intended for more advanced users running newer equipment and software. If you experience major problems with RadarLab, we recommend that you revert back to the standard weatherTAP imagery.
RadarLab works best at 1024x768