(S (S (NP (NP (BASENP (NNS Forces)) (PP (JJ such) (PP (IN as) (NP (BASENP (JJ heavy) (NNS storms)) (CC or) (BASENP (NNS hurricanes)))))) (PRN (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBP churn) (BASENP (NN water))))) (COMMA ,))) (VP (MD would) (VP (VB have) (BASENP (DT an) (NN effect))))) (PERIOD .))