Late season North Atlantic basin tropical cyclone (TC) genesis events often favor the western Caribbean Sea and Gulf of Mexico. The development of TC Ida in early November 2009, like the similar development of TC Paloma one year earlier, is an excellent example of a late season TC genesis event in the western Caribbean. TC Ida developed from a low-level vorticity maximum situated just north of Panama. Noteworthy was the presence of 5-10 other candidate low-level vorticity maxima within a radius of 2000 km, none of which developed into a TC, prompting the question as to how to distinguish developing from non-developing vorticity centers in advance. Environmental features important to the Ida genesis were anticyclonic wave breaking, barotropic instability, a cool surge through the Gulf of Tehuantepec, and the presence of a potential vorticity streamer to the north that facilitated upper-level outflow and deep warm-air advection to the north of the storm. The presence or absence of mid-level moisture in conjunction with vertical shear profiles appeared to be development discriminators in this case.