Yes, It's possible .. I'm not sure I recommend it.
My radar (KMUX) has been flakey for about 2 days with it dropping off and on. I find the last status message helpful to show what's going on, and even if it is active for now, the event may continue.
To do what you'd like to do (suppress messages if current status is active), just change
if (isset($radarMsgs[$myRadar])) {
foreach ($radarMsgs[$myRadar] as $timestamp => $msg) {
to
if ($statColor <> '#33FF33' and isset($radarMsgs[$myRadar])) {
foreach ($radarMsgs[$myRadar] as $timestamp => $msg) {
and that should do it.
I should point out that the script eliminates duplicate messages for a particular radar (based on identical timestamps), unlike the raw feed page from the NWS
Best regards,
Ken