Averaging hourly station data

[DaNa L. Carlis]

Hi Users,

I would like to plot a line graph using station data that is divided by
hourly increments and contains wind speeds.  First of all, I would like to
calculate the average wind speed of each day for a two month period and
produce a time-series plot of the two months.

Also, I would like to calculate the average 00Z, 06Z, 12Z, and 18Z wind
speed and plot a time series as well.  My original thoughts were to use the
stnave function which is somewhat similar to the ave function, but working
with station data is a little different.  I found somewhere in the archive
that stnave can use time increments but I haven't been able to get it to
work.  I use the following command:

'd stnave(wspd(stid=xxx),t=1,t=1488,24,-m 60)'

and I get the following error message:

Error from STNAVE:  X, Y varying environment required
Operation Error:  Error from stnave function
  Error ocurred at column 1
DISPLAY error:  Invalid expression
  Expression = stnave(wspd(stid=xxx),t=1,t=1488,24,-m60)

I thought that when using station data one had to
'set x 1'
'set y 1'
'set t 1 last'
'd wspd(stid=xxx)

This sequence will actually plot the line graph, but I need to average the
data.  I'm assuming that I'm going at this all wrong so I could really use
some help!  This is my first time working with station data.  Thanks!!