Plains<span> occur as lowlands along the bottoms of </span>valleys<span> or on the doorsteps of mountains, as coastal </span>plains<span>, and as plateaus or uplands. In a </span>valley<span>, a </span>plain<span> is enclosed on two sides but in other cases a </span>plain<span> may be delineated by a complete or partial ring of hills, by mountains or cliffs.</span>
It would be stormy because weather moves eastword in the US.
Arid
<span>Lacking moisture, especially having insufficient rainfall to support trees or woody plants</span>
Among all the countries that you mentioned, Gabon is the country that receives the most rainfall.