In the Settings.php, you have $SITE['GR3type'] = 'cr'; // radar image type 'cr','br','cr248','br1' etc.
which overrides the $GR3type setting in the script (when included in a template page).
Change Settings.php to have $SITE['GR3type'] = 'br'; // radar image type 'cr','br','cr248','br1' etc.
and wxnewpage.php should work also.