Tuesday 29 May 2018

Journalists die in North Carolina as Tropical Storm Alberto makes landfall in Florida.

Tropical Storm Alberto made landfall in Bay County, Florida, on Monday 28 May 2018, bringing high winds and flooding to much of the southeastern United States. Two people are known to have died as a result of this storm, Mike McCormick and Aaron Smeltzer, journalists employed by television station WYFF who were killed when a falling tree struck their vehicle as they covered the storm in North Carolina.

Floodwaters in Wakulla County, Florida, as Tropical Storm Alberto made landfall on 28 May 2018. Southeast Area Weather/Twitter.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

 The passage of Tropical Storm Alberto till 8.51 am GMT on mOnday 29 May 2018 (thick line) with its predicted future path (thin line). Colours indicate the strength of the storm. Tropical Storm Risk.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides, which are 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.
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