Manuel and Ingrid (2013) over Mexico: Effects and Impacts

The centers of Tropical Storm Manuel and Hurricane Ingrid moved over mainland Mexico on 15 and 16 September 2013, respectively. Manuel had developed as a tropical depression in the eastern tropical Pacific basin off the coast of the State of Guerrero on 13 September and Ingrid had developed in the southern Gulf of Mexico on 12 September and reached category 1 on 14 September. Even though these were not particularly intense systems, the combined effect of the steady rains that affected a large part of the country, led to extensive damage and a total of 157 deaths (mostly due to fresh water flooding and landslides). Two tropical cyclones making landfall in Mexico almost simultaneously is not a common event, having previously occurred 58 years ago. This rare situation observed in September 2013 highlights the unique challenges that Mexico faces being impacted by systems from two separate basins.

The large-scale and synoptic environments were favorable for the genesis and development of the two systems that separately may not have been an unprecedented threat. However, the simultaneous systems led to a huge loss of life, as well as massive damage to infrastructure and to subsistence agriculture, which is widespread in many of the municipalities affected by the heavy rains. The persistent precipitation observed from each system was the result of trajectories being close enough to land (even when the centers were offshore), combined with the enhancement due to orographic forcing on both eastern and western mountain ranges. The intense precipitation caused over flooding of riverbanks and saturated slopes leading to landslides.

We investigate the flow of official warning and forecast information from the Federal Civil Defense Agency down to the municipal level. In particular we evaluate two municipalities as case studies (Pungarabato and Tlacoapa), both located in the State of Guerrero. We also analyzed the official forecast issued by the U.S. National Hurricane Center and its changes as the systems evolved in time and highlight the degree of coordination between different government levels. A non-linear econometric model previously developed, is used to estimate losses in maize production due to the extreme precipitation and the associated medium-term effects on child malnutrition. We conclude that the social and environmental vulnerability of large segments of the population in the State of the Guerrero, together with mis-coordination of the flow of information and response-preparedness by some local authorities, may be responsible for the disaster where about 65% of the fatalities occurred.