@ Olster :
going around weather is imperative particularly in the continental North America where there is complete upper radar coverage coupled with an ATC system designed to facilitate same.
Significan WX yes but ATC radar cannot see CAT , only build ups/ fronts, CBs, etc. . For CAT we rely on PIREPs and we pass it on automaticaly as a warning, but not every airline changes altitude . US airlines are very sensitive to it, European less.