Relevant information about the
METAR java viewing tool
The Java Applet uses version 1.1 of Java and therefore requires Netscape 4.06 or higher
or Internet Explorer 4 or higher and will not work on earlier versions. Nearly all of the
newer browsers work including Firefox, Mozilla, Safari. First, a caution about download
time. The Applet contains a 101 KB bytecode Java archive file (JAR) plus a 23 KB
map file. Downloading via slow modems could take a full 2 or 3 minutes so please be
patient (the wait is well worth it).
How to use the Applet
The Java Applet should create a map of the contiguous U.S. with
a handful of weather stations plotted around the country. Simply move your mouse over a
displayed station and you should get a pop-up of the full raw text METAR. Initially the
map displays only the biggest cities without clutter due to other neighboring cities. Drag a
box (meaning to depress the mouse button and simultaneously move your mouse) and you will
create a "rubber band" to zoom into any portion of the map you choose. Subsequently
releasing the mouse button will cause the software to zoom into the boxed region and a series
of new sites to be plotted. The default clutter algorithm will
prevent neighboring stations from being plotted if they are too close to other stations.
Successively zooming into smaller regions will eventually plot all available data (see a
useful alternative described in the last paragraph).
You may then use the Reset or Unzoom
buttons to return to previous zooms or the contiguous U.S.. Alternatively, if you are viewing
a zoom region, you may click the Overview button for a pop-up window of
the U.S. plus a red box indicating the viewing region. Simply click and drag this
internal red box to another portion of the country and the map and data plot will shift
Next, you have the choice of which variables to plot. Simply click
to check or uncheck the variables shown which currently include: Temperature, Dewpoint,
Wind Barb, Altimeter,
Weather symbol, Cloud Ceiling, Visibility,
and Station abbreviation. If you need more help concerning the station information displayed,
then view the surface help page.
Additionally, you may overlay certain map features including U.S. Counties.
Lastly, you have control over the density of the observations
displayed on the screen. The final series of buttons on the right allow you to increase or
decrease the density of stations plotted. When viewing fewer variables on a close zoom, you
may find displaying all sites useful. Or, choose only windbarbs for the whole country and
turn on all sites for an impressive view of all winds in the U.S. Be careful though:
the software will happily plot things in extreme ways even if clutter becomes extensive.
Paddy McCarthy, a co-worker here at NCAR-RAP, is responsible for creating this code.
I cannot thank him enough.