Weather Grabber
Description
The National Weather Service is a part
of the
National Oceanic and Atmospheric Administration and is charge of providing
weather forecasts and warnings all around the U.S. You can find all sorts of
great weather maps, weather data, climate news, and information on natural
disasters on their Web pages.
One of the services provided by the National Weather Service is their
Internet Weather Source, an online
source for weather maps, current conditions, and weather forecasts. The NWS
maintains a network of automated weather monitoring stations all around the
country, most operating from airports. The purpose of these weather stations is
to provide current weather information for aviation. The stations make their
data available over the Internet in a special format called
METAR.
The METAR codes form a very abbreviated summary of the weather conditions at
the various reporting stations. The NWS provides a
detailed description of the METAR system and codes. A METAR report is in
the form:
2001/11/17 15:38
KSGS 171538Z AUTO 19005KT 7SM CLR M01/M05 A3021 RMK AO2
A fresh copy of this report can be obtained by pointing your Web browser
(or Python program) to
ftp://weather.noaa.gov/data/observations/metar/stations/KSGS.TXT.
You can probably already guess about some the features of the METAR code. The
following table summarizes some of the important features of this particular
METAR report:
| 2001/11/17 |
The date of the last observation. |
| 15:38 |
The time of the last observation. (Note: This time is in 24-hour format
and is expressed in GMT (Greenwich Mean Time) or Zulu in
aviation-speak.)
|
| KSGS |
The four-letter station code. KSGS is the station at the South St.
Paul Municipal-Richard E. Fleming Field Airport. Other station codes can be
found by searching by state and airport at the
Internet Weather Source page
(use the United States Weather search).
|
| 171538Z |
This is a further abbreviated field indicating the date and time (Z for
Zulu )
|
| AUTO |
The KSGS station reports its data automatically. |
| 19005KT |
Wind direction and velocity. This indicates a direction of
190 and a velocity of 05 knots. This field can be more complicated
if there are wind gusts. You might see something like 19010G25KT which
means that winds are at 10 gusting to 25 knots.
|
| 7SM |
The visibility is 7 statute miles. |
| CLR |
The sky is clear |
| M01/M05 |
The current temperature is -1 C and the dew point is -5 C.
(Negative (minus) numbers are indicated by the M in front of the
numbers.)
|
| A3021 |
The atmospheric pressure is 30.21" of mercury. |
The NWS also provides a
short guide that lists more of the common METAR codes.
Input
Your program should prompt the user for a four-letter METAR station code.
Output
Your program will take the METAR station code, retrieve the relevant weather
data, and print a summary of the current conditions. You must print at least
the current time, date, temperature, wind speed and direction.
If you finish your program before the due date, begin added the other fields.
Sample run
The following is the minimum you are expected to complete. Add more
features as time allows.
Current weather conditions
This program retrieves the current weather conditions from the National
Weather Service. Enter a four-letter station ID (e.g., 'KSGS')
Get weather from what station? KSGS
Current conditions for KSGS
Last observation: 2001/11/17 at 15:38 GMT
Temperature: -1 C (30 F)
Wind: S at 6 mph (5 knots)
Going further
There are many ways to extend this program:
- Include more METAR data in your report.
- Calculate the wind chill. The National Weather Service has published a
new wind chill formula that you should use as a reference.
- Investigate using
regular expressions to pull out the weather information. Regular
expressions are a very powerful tool that are defintely
worth learning.
|
