Hurricane Patricia struck Culxmala, Mexico, a little after 6 pm on Friday, October 23, 2015. The tropical storm is still racing eastward and inland across central Mexico. National Weather Service (NWS) indicates Patricia is one of the strongest Saffir-Simpson Category 5 hurricanes ever recorded, reaching barometric pressures as low as 879 millibars, while packing sustained winds over ocean of 200mph with incredible gusts up to 235mph and higher, prior to making land fall as a somewhat weaker Category 5 storm. Once the storm made landfall, it rapidly reduced to Category 4 hurricane while moving inland from the coastal areas with lesser sustained wind speeds of around 130 mph.
Hurricane storm surge, flooding, and mud slides may be the greatest damaging effect from this major storm’s landfall. Along with storm surge and high winds, Patricia is bringing an incredible amount of predicted rainfall. Many areas are expected to get from 8-12 inches of rain while other areas may get more than 20 inches of rain in a single day. The topography of the Mexican Riveria, along the west coast, is home to many large well built hotels and large estate homes surrounded by indigenous barrios with weak engineering. Those smaller villages are particularly vulnerable to flash flooding along steep hillsides that rise quickly from sea level near vacation spots like Puerto Vallarta, Mazatlan, and Manzanillo.
Storm tracker Lauren Forney said, “What was particularly remarkable about this storm is the relatively short time in which hurricane Patricia intensified from a tropical storm to a Cat. 5 in less than 24 hours, and that is really unprecedented.” This fact is remarkable. Usually a Cat. 5 storm takes a number of days to evolve into the strongest of hurricanes. Most meteorologists and oceanographers tend to agree that in 2015, a strong warm El Niño current is the likely cause contributing to such a rapid increase in storm scale over such a short time. Lauren also indicated that “this storm is a great case study, from a disaster response perspective, as it really highlights the importance of computing these type of strong ‘outlier events’ into our emergency preparedness planning. These types of large scale dangerous weather events can and do happen.”
Modern risk assessment theory takes into consideration ‘high consequence’ events, such as major hurricanes. For example, when engineering for earth quakes, standards in middle America are generally lower than those for Southern California, for obvious reasons, a recent exception being Oklahoma. Frequency or likelihood of occurrence is a factor in natural risk assessment, while consequence is another consideration for estimating risk. When you combine increased probability, such as a strong El Niño effect and a high consequence outcome, such as a major hurricane landfall, the area is then facing increased risk. As weather and topographical changes evolve, so do population increases into vulnerable areas, such as river deltas and flood plains. Emergency plans of yesterdays past should be updated to account for changing conditions resulting from major shifts in climate, topography, and population.
Mexico is in need of support. If you are interested in volunteering or donating, most NGOs recommend sending support to International Red Cross.