There's a world-wide network of ICAO stations which provide weather
observations and forecasts. The information is intended for aviation, but it is
useful for anyone who want easy access to world-wide weather conditions and
forecasts.
The four-letter ICAO code can be used to obtain hourly
METAR observations and TAF forecasts for the location. METAR and TAF are French
acronyms. The former refers to aviation routine weather report, and the latter
as terminal aerodrome forecast.
According to the Texas A&M
Department of atmospheric sciences, "The METAR code is a precise, easy to read
code which provides a great deal of information. The code format is also used
by most of the world to provide pilots with trend forecast weather at air
terminals to which they are flying. This code has been adopted as the
international code for reporting weather conditions by all nations." The U.S.,
of course, has taken a couple of exceptions to the standard. TAF reports can
also vary by country
One can obtain raw text METAR and TAF reports
quite easily over the internet via FTP (or HTTP.) Despite the words from Texas
A&M, decoding these raw texts can be fairly complicated. In general, you
need to parse each code group, identify its type, and then decode the
observation or forecast. There are a lot of potential codes, but many programs
simply short-cut the process by looking for the basics and discarding anything
unknown..
http://metar.noaa.gov/table_master.jsp?sub_menu=no&show=guide.html&dir=./documents/&title=title_helpful
takes you to a ‘quick reference guide’ to decoding, and
http://www.avweb.com/weather/metarabv.html
takes you to a complete list of METAR and TAF abbreviations:
To make
life easier you can download a pre-decoded METAR from NOAA using a URL like
ftp://weather.noaa.gov/data/observations/metar/decoded/KMQE.TXT
or download the raw report with
ftp://weather.noaa.gov/data/observations/metar/stations/KMQE.TXT
and decode it yourself. KMQE is the ICAO code for the METAR site at East
Milton, MA.
TAFs can be downloaded using
ftp://weather.noaa.gov/data/forecasts/taf/stations/KBOS.TXT,
but there is no decoded version in that directory. KBOS is the ICAO code for
the TAF site at Logan Airport, Boston.
A complete list of ICAO
stations with some detailed information about each including latitude,
longitude and elevation, is maintained at
http://www.rap.ucar.edu/weather/surface/stations.txt
Some ICAO locations in the U.S. are also sites for NEXRAD (next
generation weather radar.) These radars offer several different 'products' or
types of data and/or image.
NEXRAD images are fairly easy to obtain
via HTTP. You just need to know (or be happy with) the type of image (product)
that a particular URL will produce. Visit a URL like and
http://radar.weather.gov/radar/latest/DS.p19r0/si.kbox.shtml
and examine the other URLS of thevarious available images. Naturally, you can
omit the page and download the image directly, using a URL like
http://radar.weather.gov/radar/images/DS.p19r0/SI.kbox/latest.gif.
The section of the URL between the ‘DS.’ and the SI.’
defines the specific radar product. KBOX is the NEXRAD site in Taunton, MA.
The directory referenced in the URL actually contains all the files from
the last available sequence of images. All but the last image in the sequence
are named using their time/date stamp, so the actual names are unpredictable.
The site permits directory listings, however, so if you use the same URL
without the filename (http://radar.weather.gov/radar/images/DS.p19r0/SI.kbox/)
you will get a page listing all the filenames of the latest image sequences.
Parse the html and download those files to have a sequence of images which may
be animated.
You’ll notice that the native NWS images have a
black background, so they can be superimposed on a more colorful or detailed
geographical map. The ICAO list referenced above indicated which are also
NEXRAD sites.
According to http://weather.gov/om/marine/wxradio.htm,
SAME geographic codes are used to program SAME-capable NOAA Weather Radio
receivers to receive alert messages for user-specified areas. If you have such
a receiver, these codes are useful.
A complete list of SAME location
codes is maintained at http://www.nws.noaa.gov/nwr/SameCode.txt.
NOAA is home of the National Weather Service (NWS) which has provided
its forecast information by a county-based 6-character ‘zone’
code. You can obtain a straightforward text forecast, for example, using a URL
like http://weather.noaa.gov/pub/data/forecasts/zone/ma/maz022.txt,
or one like http://www.srh.noaa.gov/data/forecasts/MAZ022.php
will produce a more elaborate HTML page complete with graphics.
MAZ022
is the NOAA zone for Barnstable Country, MA.
These NOAA zones are
sometimes referred to as ‘warning zones’ because the National
Weather Service also has issued its special weather statements using these
zones.
Most NOAA sites no longer require the zone, just the zip code
or city and state. As it says here, http://www.erh.noaa.gov/er/box/,
The point and click forecasts
below are generated directly from the National Digital Forecast Database. They
are no longer "Zone" or County based forecaster manipulated text products, but
rather point specific text products generated "on-the-fly" from gridded
forecast fields prepared by National Weather Service Meteorologists.
Nevertheless, using the zones produces a more compact URL, and those cited
above will produce accurate working forecasts.
This forum
entry,
http://www.weather-watch.com/smf/index.php/topic,9220/prev_next,next.html,
offers directions to a couple of versions of the complete zone/county lists,
but you have to join Weather-Watch to be allowed to download.
There are other ways to get your weather, of course, and may of those
are free. Some provide easy ways to create a block of code which can be
inserted into a web page to display the latest weather (and of course to link
back to their commercial sites.) If you search the web using 'weather gizmo,'
'weather button,' 'weather ticker,' or similar phrases, you'll find plenty of
options, or visit your favorite commercial site and look around.
At
least one commercial site (MSNBC) also permits free direct links to their raw
data. It's in its own proprietary format and largely undocumented, but through
trial and error a lot of PHP scripts have been developed to access and decode
it. The risk, of course, is that the format or the access rules might be
changed at any time. I know of no complete list of MSNBC weather geographic
codes; you have to figure them out by using their regular page, entering a zip
code, and examining the URL of the result page to find the embedded code.
Maintained (such as it is) by rgm at fabbnet.net
