TRMM - STAN CAUSES FLOODS WITH DEATHS IN CENTRAL AMERICA

Link to image of STAN OCT 4, 2005 15dBZ 3d isosurface

STAN HITS SOUTHERN MEXICO, TRIGGERS MUDSLIDES IN CENTRAL AMERICA Despite hitting a relatively remote section of the Mexican coastline as a Category 1 hurricane, Stan's effects were felt across the region as 49 people died in El Salvador as a result of mudslides brought on by storms that were triggered by Stan. A total of 65 people perished across the entire region as a result of the Stan. Stan became the 18th named storm of an extremely active 2005 hurricane season on the 1st of October 2005 just east of the Yucatan Peninsula in the far western Caribbean. Moving west, Stan quickly made landfall on the Yucatan Peninsula, which it traversed as a weak tropical storm. After re-emerging over warm water in the Bay of Campeche, Stan turned to the southwest and began to intensify. The storm, however, did not have much room to grow over water before encountering the Mexican coastline and so made landfall south of Vera Cruz, Mexico as a Category 1 hurricane.

The Tropical Rainfall Measuring Mission (TRMM) satellite has been monitoring the storm. TRMM was launched in November of 1997 to measure rainfall over the global Tropics and has proven itself to be a valuable platform for observing tropical cyclones. This first image was taken at 10:20 UTC (6:20 am EDT) on 2 October 2005 as Stan was coming ashore on the Yucatan Peninsula. The image displays the horizontal pattern of rain intensity within Stan as obtained by TRMM's sensors. Rain rates in the center part of the swath are from the TRMM Precipitation Radar (PR), the only radar capable of measuring precipitation from space. The PR can provide fine resolution rainfall data and details on its vertical structure. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). The image shows that Stan is still rather poorly organized with an ill-defined eye (the center is located in the TMI swath within the large blue area of light rain) and an asymmetric rain field. At the time, Stan was a weak tropical storm with maximum sustained winds reported at 40 knots (46 mph) by the National Hurricane Center (NHC).

The next image from TRMM was taken at 10:05 UTC (6:05 am EDT) on October 4th and shows Stan making landfall along the coast of Vera Cruz, Mexico. A band of intense rain (dark red areas) is visible as part of the eastern eyewall with additional heavy rain associated with an outer rain band located just offshore along the coast. The third image was taken at the same time and shows a dramatic 3D perspective of Stan. The vertical height of the isosurface (15 dBZ) is determined by the height of the precipitation-sized particles within the storm as detected by the TRMM PR. The tall towers (in red) just east of the center extend up to 17 km and are associated with the area of intense rain in the eastern eyewall as shown by the previous image. These towers can be a sign of future strengthening and likely indicate that Stan was in the process of intensifying as it approached the coast. As water vapor condenses into the cloud droplets that produce rain, heat is released. This heat, known as latent heat, is what drives the storm's circulation. It is most effective when it is released near the core of the storm as is the case here with Stan. At the time of these images, Stan was a Category 1 storm with maximum sustained winds reported at 65 knots (75 mph) by NHC.

The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides estimates of rainfall over the global Tropics. The final image shows MPA rainfall totals over southern Mexico and the surrounding region for the period 29 September to 5 October 2005. Totals immediately along the path of Stan are on the order of 100 to 250 mm (4 to 10 inches) with locally higher amounts across the Bay of Campeche and adjoining coastal areas. The Pacific coastline of southern Mexico, Guatemala, and El Salvador also received upwards of 150 mm (6 inches) of rainfall.