Introduction to WXP
The Weather Processor
What is WXP?
WXP (The Weather Processor) is a set of analysis and visualization programs for
standard meteorlogical data. The goal of the software package is to give the user a
means for ingesting data from the National Weather Service (NWS), decoding the data,
parsing the products, and visualizing the data.
WXP was initially developed at Purdue University in the early 1980s as a set of
programs written in the Basic programming language to quickly analyze meteorological data
on IBM PCs. In 1986, Purdue got a grant from IBM to develop meteorological analysis
software on IBM's new Unix platform (the IBM RT) in which the original Basic code was
ported to C and enhanced into a fully functional weather analysis package. During
the winter of 1988, WXP was displayed at the American Meteorlogical Society (AMS) Annual
Meeting during which it was successfully ported to a Sun workstation. As a result of
that port, WXP was adopted as the primary Unix analysis package for the Unidata community.
Unidata is a National Science Foundation funded group to provide universities with access
to weather data and analysis software. In the following years, WXP grew as more than
50 universities became licensed to use it. During the same period, the Purdue Research
Foundation became responsible for selling and licensing to the private sector. In
the early 90s, WXP became the focus of a project called Campus Weather Display, which was
an effort to use WXP to automatically generate graphics for an kiosk-like system based on
FTP. This set up WXP for use with Gopher and eventually, the World Wide Web.
WXP is one of the top weather analysis packages for generating images for web sites.
In 1999, Unisys corporation took over responsibility for developing, maintaining and
Today, WXP (version 5.0) has matured into a robust analysis package. Its toolkit
nature makes is ideal for weather data processing and batch generation of products.
It uses X windows (Unix) and Win32 (Windows 95/98/NT) for graphics display and has a
postscript and HPGL driver for hardcopy. It is a menu driven software package that
has strong command like and resource interface for tailorability. It manages and
visualizes most of the data presented on NOAAPORT and the Family of Services.
WXP's Input Data
WXP is set up to use data from the National Weather Service including:
- Family of Services (FOS) - This is the traditional NWS feed of data
which is split into circuits for observations and analyses (Domestic Data), forecasts and
advisories (Public Products), and gridded model data (High Resolution Data).
Generally, FOS data is provided through a commercial data provider or to universities
using Internet Data Distribution (IDD).
- NOAAPORT - This is a relative new service provided by NWS which allows
access to all the data that is on FOS and adds extra model grids, NIDS radar data
and high resolution satellite imagery.
NOAAPORT and FOS data are not required in order to use WXP. Data with similar
formats can be used or transformed into format WXP can use. WXP has a generic raw
(value at a point), grid and image file formats.
WXP has direct support for the following data formats:
- Surface Data (Metar/Sao) - This include standard surface observation
reported once an hour (if not more frequent).
- Synoptic Data (Synop/Buoy/Dribu/Cman) - These data are similar
to surface data but are reported less frequently (once every 3 or 6 hours).
- Upper Air Sounding Data (TTAA/BB/CC/DD-PPAA/BB/CC/DD) - This is the
data recorded from balloon launches done every 12 hours (sometimes every 6 hours).
The data are encoded into various formats.
- Manually Digitized Radar (MDR) - This is digitized radar echos from the various
radar sites across the US. This data are updated once an hour.
- Radar Coded Messages (RCM) - This is higher resolution radar data from
Nexrad sites (~11km) and is a replacement for MDR.
- Nexrad Data (NIDS) - This is the format for Nexrad radar output which
includes several parameters including reflectivity, precip, velocity, and winds.
- Radar Mosaics (Unisys/WSI Nowrad/Kavouras) - Supports display of these
- Lightning Data (various formats) - Supports several formats of
- Profiler Data (various formats)
- GRIB Data (most formats) - Supports all NWS GRIB and most ECMWF and
- Satellite Images (McIDAS AREA/GINI/Unisys) - Supports these types of
formats for satellite imagery.
- Model Output Statistics (MOS) Data - This is statistical data output from
the large forecast models. This is encoded into specific formats based on the type
of model output. These are sent once every 12 hours.
- Hydrological Data - This includes reports from various hydrological sites
including max/min temperatures, precipitation and river and lake information.
- Hurricane Data - Decodes hurricane advisory data.
- Text Data - Parses various text products including forecasts,
summaries, advisories, watches and warnings.
What WXP does with the data
You can organize the above data into two categories:
- TEXT - This is simple alphanumeric text which includes summaries, advisories and
forecasts. Usually very little is done with this data other than to display the
data. WXP has several programs that parse through this information to display
specific products for specific locations for specific times.
- DATA - This represents everything else on the feeds. These are often coded
observations, coded forecasts or model output. To parse this data often
provides little or no relevant information. This data often must be decoded and then
displayed either plotted (individual station data on a map) or contoured.
WXP is a toolkit of programs which allow you to access, process and display each of the
above data types. The WXP toolset of programs can be put into the following groups:
- INGESTORS - This is the process of reading in the data feeds and saving the
information to disk. There is a selection method used to first select which of the
broadcast products will be saved and second, a way of splitting the data up into smaller
more managable files. For university sites, this is done with the LDM program
from Unidata. For other sites, this is done with the WXP ingestor.
- PARSERS - These programs parse information from the TEXT based products.
There is a mechanism for searching for specific products including individual zones.
- DECODERS - These programs decode specific types of data and produce intermediate
data files. The idea behind decoders are to reformat the data in a way that WXP can
access the data more efficiently.
- ANALYSIS and CALCULATION - This process is often buried inside other programs.
Essentially, this is processing the data and producing new parameters and data.
- VISUALIZATION - The bulk of the WXP programs are actually used to visualize the
data. This includes plotting data on maps, producing sounding plots, contouring
data, etc. These programs also perform extensive computations on the data to produce
Now you have a feel for what WXP does. Now on to the Tutorials.
For further information about WXP, email firstname.lastname@example.org
Last updated by Dan Vietor on June 20, 2001