Extratropical transition technique

The extratropical transition (XT) technique is a system used to subjectively estimate the intensity of tropical cyclones undergoing transition into extratropical cyclones based on visible and infrared satellite imagery. The system is used by the Joint Typhoon Warning Center (JTWC) in place of the Dvorak technique, as the loss of central convection in transitioning tropical cyclones can cause the Dvorak technique to fail; [ [http://www.nhc.noaa.gov/pdf/06velden.pdf untitled ] ] the loss of convection results in unrealistically low estimates using the Dvorak technique. [http://ams.confex.com/ams/pdfpapers/75346.pdf]

Technique details

The system combines aspects of the Dvorak technique, used for estimating tropical cyclone intensity, and the Hebert-Poteat technique, used for estimating subtropical cyclone intensity. [ [http://home1.gte.net/anstett/XT_Pg01.htm JTWC TN 97/002 Page 1 ] ] 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. [http://home1.gte.net/anstett/XT_Pg08.htm JTWC TN 97/002 Page 8 ] ] 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. [http://home1.gte.net/anstett/XT_Pg02.htm JTWC TN 97/002 Page 2 ] ] Also, the XT technique is only used once extratropical transition begins; the Dvorak technique is still used if the system begins dissipating without transition. Once the cyclone has completed transition and become cold-core, the technique is no longer used.

ee also

*Tropical cyclone
*Extratropical cyclone
*Dvorak technique
*Hebert-Poteat technique

References

External links

* [https://metocph.nmci.navy.mil/jtwc.php Joint Typhoon Warning Center]