The coexistence of different regimes in a class of atmospheric flow models is analyzed from the standpoint of irreversible thermodynamics. The entropy production, measuring the degree of dissipation within the system is evaluated across the bifurcation point. Some interesting trends are brought out, regarding the relative importance of dissipation in two qualitatively different circulation regimes referred to as zonal and blocked flows. It is shown that in the presence of stochastic disturbances entropy production exhibits critical behavior both in the vicinity of the bifurcation point and in parameter values where the two flow regimes are equally probable.