Tropical Storm Marty Tries to Strengthen South of Mexico
Tropical Storm Marty, which formed into an depression from an area of low pressure about 300 miles southwest of Acapulco, Mexico Saturday afternoon (local time), has been trying to strengthen while drifting slowly northward toward the southwest coast of Mexico. This first image was captured by NASA's GPM core satellite at 00:11 UTC 27 September (7:11 pm CDT 26 September) just a few hours after Marty had formed into a tropical depression. GPM shows substantial areas of rain on the eastern half of the storm, but more importantly, there is already evidence of curvature and banding within those areas of rain, indications that a cyclonic circulation is becoming established. Furthermore, there are areas of heavy rain located near the center (in red).
The next image, taken at the same time, shows a 3D perspective of Marty from the GPM DPR. It shows that those areas of heavy rain near the center are associated with a deep convective tower that reaches up to 17.5 km (highlighted in red). When these "convective bursts" as they are known occur near the cyclone's center, they can be a sign of intensification due to the associated release of heat into the storm's core. Based in part on this information, the National Hurricane Center (NHC) upgraded Marty to a tropical storm in its following advisory.
The next set of images were taken by GPM Monday morning at 10:41 UTC (5:41 am CDT) on the 28th. The first image shows just the rainrates estimated from GPM. At this time, several prominent rainbands are clearly evident and appear larger and more robust than in the previous image, an indication that the storm is continuing to become better organized; however, they are again located primarily east of the center of circulation. This is due to the effects of westerly wind shear, which is inhibiting Marty's ability to strengthen. Despite this, the presence of yet another convective burst evident in this last image shows Marty is continuing to battle the shear and is at least likely to maintain its strength in the short term.