Why are some TCFA areas shaped like a circle and others like a rectangle?
Rectangular TCFAs are used when the developing cyclone’s location and movement can be reasonably predicted. Circular TCFAs are used if the movement cannot be reasonably predicted or if the developing cyclone is nearly stationary. Back to top Q: How often are warnings updated by JTWC? A: North Pacific tropical cyclone warnings are routinely updated every six hours. Indian Ocean and South Pacific tropical cyclone warnings are routinely updated every twelve hours. The REMARKS section of each warning bulletin lists the times when the next warnings are scheduled. When JTWC issues the final warning for a tropical cyclone, no additional warnings are issued unless the cyclone regenerates. Back to top Q: When are warnings available? A: JTWC products are transmitted not later than 3 hours past the synoptic hour from which a warning has been created. As the synoptic hours are 00Z, 06Z, 12Z, and 18Z, warnings will be available by 03Z, 09Z, 15Z, or 21Z. Back to top Q: What is the shaded area around
