( AIR-MASS ( ( THUNDERSTORMS ( ( This method ) ( is ( ( a ( ( reasonably simple ) method ) ) ( for ( ( forecasting ( air-mass thunderstorms ) ) ( in ( the ( Eastern ( United States ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP AIR-MASS)) (VP (VBZ THUNDERSTORMS) (SBAR (S (NP (DT This) (NN method)) (VP (VBZ is) (NP (NP (DT a) (ADJP (RB reasonably) (JJ simple)) (NN method)) (PP (IN for) (S (VP (VBG forecasting) (NP (JJ air-mass) (NNS thunderstorms)) (PP (IN in) (NP (DT the) (NNP Eastern) (NNP United) (NNPS States))))))))))) (. .)))
AIR-MASS THUNDERSTORMS This method is a reasonably simple method for forecasting air-mass thunderstorms in the Eastern United States.
(ROOT (S (NP (NP (DT The) (JJS best) (NN explanation)) (PP (IN for) (SBAR (WHADVP (WRB how)) (S (NP (NN air) (NNS masses)) (VP (VBP move) (PP (IN across) (NP (DT the) (VBN united) (NNS states)))))))) (VP (VBZ is) (SBAR (IN that) (S (NP (DT the) (VBG prevailing) (NNS westerlies)) (VP (VP (VBP move) (NP (NN air) (NNS masses)) (PP (IN from) (NP (NN west))) (PP (TO to) (ADJP (JJ east))) (PP (IN across) (NP (DT the) (VBN united) (NNS states)))) (CC but) (VP (MD may) (VP (VB be) (VP (VBN deflected) (PP (IN by) (NP (DT the) (NN jet) (NN stream)))))))))) (. .)))