An advanced model has been developed for predicting the behavior of a fiber as it is formed in the melt blowing process. The model involves the simultaneous solution of the momentum, energy, and continuity equations. Crystallization effects are included. The model equations are solved numerically. As a bottom boundary condition in this solution, a "stop point" is assumed. The stop point is the point where (a) the fiber stress is zero, and (b) the air velocity and fiber velocity are equal. Predicted parameters include fiber diameter, velocity, temperature, stress, and crystallinity. The predicted results show that very little online crystallization takes place under typical melt blowing conditions.