Weather Station Information
The weather station at CSC is a WRL-25-ZR model from Texas Weather Instruments:
many thanks to David Patterson of TWI for his generous help in setting
us up with this instrument. It is equipped with sensors to measure air
and water temperature, air pressure, and wind speed and direction. Wind
direction is assigned by the station to one of 16 values - that's why
wind direction appears to be quantized into 22.5-degree increments.
A computer, a FIT-PC, loads sensor readings from the weather station once per second, using Virtual Weather Station
(VWS) software from Ambient Software. VWS archives the data and, every
five minutes, generates JPEG images of graphs and text derived from
weather station sensor data, which it uploads (via FTP) to CSC's
webserver. When you point your web browser to the CSC website weather
links, the web server serves the latest JPEG images on the webserver in
a webpage. This webpage is set to auto-update every five minutes, so
you don't have to manually reload the page. This also means that the
data you're looking at is never more than ten minutes old.
On the "CSC Wind Conditions"
page, all displayed data comes from the weather station. The 24-hour
plot of wind direction shows large vertical swings when the wind
changes direction slightly from just East of North to just West of
North or vice versa. This big change in the graph is actually a small
change in wind direction.
The compass-like display below this plot doesn't
behave this way. The needle points into the wind as it was at the time
of the last, or second-last, data upload to the webserver. The green
dots show wind speed and direction over the last three hours, and give
an idea of how variable the wind has been recently.
The two pie charts below the compass-like display
provide another way of looking at the last three hours of wind speed
and direction. Use them to see whether there has been a dominant speed
and direction, e.g. mostly 4-8mph, out of the East but veering SE at
On the "Weather around CSC"
page, the textual data in the "Conditions at CSC" center panel comes
from the weather station; so does the information under "CSC Graphs,
Details". The remaining information on this page consists of links to
other web weather resources. The aim of this page is to supply a
one-stop-shop for your sailing weather, with current wind and
temperature at CSC, a NEXRAD radar snapshot, any current advisories,
and cloud cover evolution. Weather station archived data is available
in the CSC Graphs, Details" section.
Data is uploaded every minute or so to the Weather Underground.
CSC weather history is archived there, in easily-accessible graphs and
tables. Note that wind gust information is not as accurate on
Weather Underground as on the "CSC Wind Conditions"
page, because the former gets a wind sample every minute, the latter
every second. As a result, Weather Underground tends to underestimate
max wind speed.
For more infomation, contact Jim O'Connor at email@example.com.