 The technique is applied when a tropical cyclone interacts with a frontal boundary or loses its central convection while maintaining its forward speed or accelerating.The XT scale corresponds to the Dvorak scale and is applied in the same way, except that "XT" is used instead of "T" to indicate that the system is undergoing extratropical transition.Also, the XT technique is only used once extratropical transition begins; the Dvorak technique is still used if the system begins dissipating without transition.