Stormy signs poor in forecast (9)
I believe the answer is:
prognosis
'forecast' is the definition.
(synonyms)
'stormy signs poor' is the wordplay.
'stormy' is an anagram indicator (stormy suggests disruption).
'signs'+'poor'='signspoor'
'signspoor' with letters rearranged gives 'PROGNOSIS'.
'in' acts as a link.
(Other definitions for prognosis that I've seen before include "Medical opinion" , "Prediction as to how something will turn out" , "Forecast, outlook" , "Medical prediction" , "Forecast of course of illness as by doctor" .)