Kal,
Yes, if you don't want to overwrite the output file, change the following instruction (line 301),
if(open(EWP, ">", $ewcumulusfile)) {
to
if(open(EWP, ">>", $ewcumulusfile)) {
Keep in mind that Cumulus reads only the last line of the output file (ewpdata.dat). Also, the file will continue to grow at the rate of one line every 12 seconds.
-Bill