U.S. Department of Commerce

FAQ (Frequently Asked Questions)

Some of these questions were taken from the Java NEXRAD Viewer FAQ. New FAQ questions for the Weather and Climate Toolkit will appear first and the question will be in blue font color.

When we export product 19 (level III) in ESRI ASCII Grid format, it shows 1200 columns and 903 rows. Product 19 (level III) should have 230 x 360 bins. What is the (column, row) value?
The native data structure of the product 19 Base Reflectivity is 'radial' in a polar coordinate system. The resolution is 1 deg by 1 km, so the dimensions are 360 deg by 230 km. The vector formats (Shapefile, WKT) preserve this structure by encoding the data as polygons, which represent the exact range bin with vertices in lat/lon NAD83 coordinates. The raster formats rasterize the data onto a lat/lon NAD83 grid. So the cellsize you see in the header is in degrees.
How do I get NEXRAD data?
NEXRAD Data must be ordered from the NCDC Archive. This can be done via the NEXRAD Inventory website or the HAS System website. If ordering from HAS, the "UnTar" option must be used.
I ordered NEXRAD data from HAS but the Viewer/Exporter cannot find it?
The "UnTar" option must be used when ordering the data from HAS. One solution is to use the new NEXRAD Inventory System website.
I have data from a non-NCDC source (LDM, etc...). Why can the Viewer/Exporter not find the data?
Right now, the Viewer/Exporter uses several standard naming conventions to indentify the data. The Level-III data must be uncompressed while Unix (.Z) and GZIP (.gz) compressions are supported for the Level-II data. Level-III data from the NWS FTP Site (sn.last, sn.0001, etc...) are now supported. More information can be found in the Viewer help page accessable from the "Help" menu.
I get a connection error when I enter my HAS number into the Viewer.
This could be a firewall ftp configuration issue. The data can also be accessed by http by entering the following under the "Custom" tab under the "NEXRAD Data Selector": http://www1.ncdc.noaa.gov/pub/has/HASxxxxxxxxx where the x's are the HAS number assigned to your order.
My GeoTIFFs look all black and/or white in ArcGIS.
ArcGIS seems to not handle 32-bit GeoTIFFs correctly, when using the 'Stretched' symbology. Try changing to a 'Classified' symbology with many classification breaks.
I tried to download/install the Viewer and got "Microsoft JScript conpilation error". Now what?
This could be a network settings issue within Java Web Start. Try the following steps to fix the problem:
  1. In Windows XP, do a "Start"-"Run" and type "javaws", or "javaws -version" if using Java version 6 or greater. This can also be done by typing "javaws" or "javaws -viewer" from the command line. This will bring up the "Java Application Cache Viewer".
  2. Click on the "Edit" menu option and select "Preferences" to bring up the "Java Control Panel". (This may also be done in Windows by selecting "Java" under "Settings"-"Control Panel")
  3. Under the "General" tab, click on "Network Settings...".
  4. Select "Direct Connection" and apply all changes.
How do I add Desktop Shortcuts or a Start Menu entry (Desktop Integration)?
  1. Right-click on the 'Launch the BETA/STABLE Version x.x.x Java NEXRAD Viewer' link and bookmark in your browser.
  2. Drag the 'Launch ...' link onto your desktop.
  3. From the Windows Start Menu, select 'Run' and type (without quotes) "javaws -viewer". This brings up the Java Cache Viewer. Select the NCDC NEXRAD Viewer application, right-click and select "Install Shortcuts". Note: This is the only method that will allow use of the software without an internet connection.