In extreme events of space weather, very large fluxes of "storm" particles are formed preceding the arrival of a shock wave into the Earth's orbit. They are the ones that pose the greatest danger to life-support systems in the upper atmosphere, in space, and on the Earth. The results have been checked of the prediction of "storm" particles accelerated by shock waves from variations in high-energy cosmic rays by measurements on the ACE spacecraft (United States). The forecast reliability is assessed at P >= 80%.