Abstract: The paper is based on real-time diagnosis about three major factors producing severe sandstorm, they are strong cold air, thermal instability and ground layer environment. Through analyzing the three factors, and according to the starting point of severe sandstorm forecast of Ningxia, we similarly test the physical structure of three-dimensional space and dynamic process which produce severe sandstorm, then permeate the comprehensive index and grouping model that have the definite sense of synoptic meteorology and have the ability to practically forecast severe sandstorms of Ningxia. In support of the technology of automatic discernment of synoptic system, and applying the amendment scheme of spiral degree we determin the falling area of severe sandstorm, and then create the automatic and objective system that can monitor and forecast severe sandstorm weather of Ningxia.

Key words: dynamic similarity filter, spiral degree amendment, severe sandstorm, forecast system