Saturday 24 October 2020

Landslide kills two in Jamaica.

Two people have after their home was destroyed by a landslide at Shooters Hill in St Andrew Parish, Jamaica, on Friday 23 October 2020. The body of Romeo Leechman, 42, was recovered following the incident, which happened at about 8.00 am local time, his daughter Saneeka Leechman, 15, was found the following day. The incident is reported to have happened following days of heavy rain in the area, associated with a low trough over the western Caribbean. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. A second home was also damaged during the incident.

 
Residents of Shooters Hill, Jamaica, searching for a missing teenage girl following a landslide on 23 October 2020. Nicholas Nunes/The Gleaner.

Low pressure systems over oceans are caused by warming of the air over the ocean, which causes the air over the affected area to rise, while fresh air is drawn in from elsewhere and in turn be warmed and rise. At the same time the heat causes high levels of evaporation from the ocean, so that the rising air is also waterlogged. Eventually this air rises high enough in the atmosphere that it matches the pressure of the air around it, at which point it stops rising and drifts with the prevalent wind. Eventually it passes into cooler areas, where it starts to lose its water as precipitation (rain), as cooler air cannot hold as much evaporated water as warmer air. As land has different thermal properties to water, this often means that the cooler areas encountered by the warm, waterlogged air are over land, leading to high rainfall in coastal areas.

Jamaica has a tropical climate, with a rainy season that lasts from May to November, with peak rainfall typically falling October, when the St Andrews Parish area typically receives about 175 mm of rain. This is driven by winds from the southeast, which bring warm, water-laden air packages from the equatorial Atlantic Ocean over the islands of the Greater Antilles. During the remaining months of the year the climate is driven by winds from the northwest, brining dry air from the North American continent.

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