NAME
Geo::WeatherNWS - A simple way to get current weather data from the NWS.
SYNOPSIS
use Geo::WeatherNWS;
my $Report=Geo::WeatherNWS::new();
# Optionally set the server/user/directory of the reports
$Report->setservername("weather.noaa.gov");
$Report->setusername("anonymous");
$Report->setpassword('emailaddress@yourdomain.com');
$Report->setdirectory("/data/observations/metar/stations");
# Optionally set a template file for generating HTML
$Report->settemplatefile(/"path/to/template/file.tmpl");
# Get the report
$Report->getreport('kcvg'); # kcvg is the station code for
# Cincinnati, OH
# Check for errors
if ($Report->{error})
{
print "$Report->{errortext}\n";
}
# If you have the report in a string, you can now just decode it
my $Obs="2002/02/25 12:00 NSFA 251200Z 00000KT 50KM FEW024 SCT150 27/25 Q1010";
$Report->decodeobs($Obs);DESCRIPTION
New for version 1.01/0.23: New WCT (Wind Chill Temperature) index calulation.
Based on the new NWS formula released For the 2001/2002 Winter. It's a bit
late (July 2002) but its there.
This module is an early release of what will hopefully be a robust way
for Perl Programmers to get current weather data from the National Weather
Service. Some new functions have been added since the 0.18 release.
Instead of having to use the built-in server/user/password/directory that
the module used to use, you can provide your own. This way if you have
access to a mirror server of the data, you can specify the servername,
account information and directory where the files exist. If you dont have
access to a mirror, then you dont have to specify anything. The old server,
etc., are still automagically selected.
Also new in this release is that the getreport function now returns an
error code and the FTP error message if anything goes wrong. Before this
was added, if the server was busy or the stations text file was missing
you couldn't tell what happened.
Another new feature is the template system. You can specify a file with the
settemplatefile function. This file is read in and all of the places in the
file where the code sees %%name%% will be replaced with the proper values.
An example template has been included. The template uses the same names as
the hashref returned by the getreport function.
And, same as previous releases, the getreport function retrieves the most
current METAR formatted station report and decodes it into a hash that you
can use.
Some users had reported that they wanted to re-decode the raw
observations later. If you store the "obs" value as a string, and you
want to re-decode it later, you can now use the decodeobs function.
I thought this would be a useful module, considering that a lot of sites
today seem to get their weather data directly through other sites via http.
When the site you are getting your weather data from changes format, then
you end up having to re-code your parsing program. With the weather module,
all you need is a four-letter station code to get the most recent weather
observations. If you do not know what the station code is for your area,
check the site at http://205.156.54.206/oso/siteloc.shtml to start your
search.
Since this module uses the NWS METAR Observations, you can get weather
reports from anywhere in the world that has a four-letter station code.
This module uses the POSIX and Net::FTP modules, so you'll have to make
sure that everything is set up with them before you can use the module.
To begin:
use Geo::WeatherNWS;
my $Report=Geo::WeatherNWS::new();
If you want to change the server and user information, do it now. This
step is not required. If you dont call these functions, the module uses
the defaults.
$Report->setservername("weather.noaa.gov");
$Report->setusername("anonymous");
$Report->setpassword('emailaddress@yourdomain.com');
$Report->setdirectory("/data/observations/metar/stations");
If you want to specify a template file, use this:
$Report->settemplatefile("/path/to/template/file.tmpl");
After setting the above, you can get the data.
$Report->getreport('station');
Now you can check to see if there was an error, and what the text of the
error message was.
if ($Report->{error})
{
print "$Report->{errortext}";
}
If you have the report in a string, you can now just decode it
my $Obs="2002/02/25 12:00 NSFA 251200Z 00000KT 50KM FEW024 SCT150 27/25 Q1010";
$Report->decodeobs($Obs);
Assuming there was no error, you can now use the $Report hashref to display
the information. Some of the returned info is about the report itself,
such as:
$Report->{day} # Report Date
$Report->{time} # Report Time
$Report->{station_type} # Station Type (auto or manual)
$Report->{obs} # The Observation Text (encoded)
$Report->{code} # The Station Code
This is the template output:
$Report->{templateout}
These are the returned values specific to the conditions:
$Report->{conditionstext} # Conditions text
$Report->{conditions1} # First Part
$Report->{conditions2} # Second Part
These are the returned values specific to wind:
$Report->{windspeedmph} # Wind Speed (in mph)
$Report->{windspeedkts} # Wind Speed (in kts)
$Report->{winddir} # Wind Direction (in degrees)
$Report->{winddirtext} # Wind Direction (text version)
$Report->{windgustmph} # Wind Gusts (mph)
$Report->{windgustkts} # Wind Gusts (kts)
These are the retunred values specific to temperature and
humidity:
$Report->{temperature_f} # Temperature (degrees f)
$Report->{temperature_c} # Temperature (degrees c)
$Report->{dewpoint_f} # Dewpoint (degrees f)
$Report->{dewpoint_c} # Dewpoint (degrees c)
$Report->{relative_humidity} # Relative Humidity (in percent)
$Report->{windchill_f} # Wind Chill (degrees f)
$Report->{windchill_c} # Wind Chill (degrees c)
$Report->{heat_index_f} # Heat Index (degrees f)
$Report->{heat_index_c} # Heat Index (degrees c)
Note: Due to the formulas used to get the heat index and windchill,
sometimes these values are a little strange. A check to see if the heat
index is above the temperature before displaying it would be a good thing
for you to do. You probably don't want to display the windchill unless
its cold either.
These are the return values for clouds and visibility:
$Report->{cloudcover} # Cloudcover (text)
$Report->{cloudlevel_arrayref} # Arrayref holding all cloud levels
$Report->{visibility_mi} # Visibility (miles)
$Report->{visibility_km} # Visibility (kilometers)
These are the return values for air pressure:
$Report->{pressure_inhg} # Air Pressure (in mercury)
$Report->{pressure_mmhg} # Air Pressure (in mm mercury)
$Report->{pressure_kgcm} # Air Pressure (kg per cm)
$Report->{pressure_mb} # Air Pressure (mb)
$Report->{pressure_lbin} # Air Pressure (psi)
Other values MAY be returned, but only if there are remarks appended
to the observations. This section of the code is more experimental,
and these names could change in future releases.
$Report->{remark_arrayref} # Arrayref holding all remarks
$Report->{ptemerature} # Precise Tepmerature Reading
$Report->{storm} # Thunderstorm stats
$Report->{slp_inhg} # Air Pressure at Sea Level (in mercury)
$Report->{slp_mmhg} # Air Pressure at Sea Level (mm mercury)
$Report->{slp_kgcm} # Air Pressure at Sea Level (kg per cm)
$Report->{slp_lbin} # Air Pressure at Sea Level (psi)
$Report->{slp_mb} # Air Pressure at Sea Level (mb)
Another note: Do not be surprised if sometimes the values come back
empty. The weather stations are not required to place all of the
information in the reports.EXAMPLE
use Geo::WeatherNWS;
my $Report=Geo::WeatherNWS::new(); $Report->getreport('khao'); # For Hamilton, OH
print "Temperature is $Report->{temperature_f} degrees\n"; print "Air Pressure is $Report->{pressure_inhg} inches\n";
# If it isnt raining, etc - just print cloud cover
if ($Report->{conditionstext}) { print "Conditions: $Report->{conditionstext}\n"; } else { print "Conditions: $Report->{cloudcover}\n"; }
AUTHOR
Marc Slagle - marc.slagle@fulkertconsulting.com