This loop of GOES-8 10.7 micron longwave IR imagery shows the westward motion of a low-level mesoscale vortex over the western North Atlantic Ocean (centered near 31 N latitude, 73 West longitude) on 15 September 1998. The vortex exhibited cloud top temperatures between +20 C (blue enhancement) and +10 C (yellow enhancement), indicating that it was a lower-tropospheric feature. Colder cloud tops (+9 C and below, red to white enhancement) indicated areas of convection or cirrus debris across the region.

The first image (at 11:45 UTC) shows the 12:00 UTC ETA model 850 hPa wind streamline analysis. The ETA model did not initialize this particular cyclonic curculation feature.