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.
See also...
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