A preflare situation in a loop structure for stability to the development of plasma waves at the chromosphere part of a current circuit of a loop is investigated. We consider the situation when plasma has the spatial gradients of the density and temperature. In accordance with Heyvarts-Priest-Rust theory such a preflare situation would typically exist when the amplitude of weak electric field in the circuit of an “old” loop in an active region begins to increase as “new” magnetic flux emerges from under the photosphere (Heyvaerts, Priest & Rust (1977)).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html