Abstract: Kibel's forecasting equations,both to the first and to the second approximation,are re-derived on the base of the principle,of thermal wind.The physical meaning of such procedure is easy to grasp.The significance of θ-lines is discussed and it is demonstrated by a graphic method,that surface isobars and isotherms must move along θ-lines with the speed numerically equal to the gradient of θ-lines.With the aid of thermal wind it is shown that there must exist the steering layer,the significance of which is discussed iri detail.Tt is demonstrated that to the first approximation,variations of pressure below and above the steering layer have opposite signs while variations of temperature are characterized by the same signs.It is proved with emphasis that the first approximation implies that isobara,as well as isotherms,at all levels within the entive troposphere are steered by the same steering layer and transmitted at the very same velocity.