Heavy rainfall due to interacting air masses
The rainfall that was experienced in several parts of the country last night was as a result of an interaction between two air masses as well as heating in the atmosphere.
“What we are experiencing is due to interaction between dry air from the Sahara and moist air from the sea,” Torgbui Gbegbie Fiamekor I, Senior Forecaster and Deputy Officer in charge of the Ghana Meteorological Agency, Kotoka International Airport, told the GNA in an interview.
He said the two air masses met and produced what is known in climatology as a vortex which is a mechanism by which moist air is raised up and condenses to form a cloud.
Torgbui Gbegbie Fiamekor said on Tuesday afternoon, a vortex developed over Nigeria and begun to move westward but instead, turned and moved into the sea.
By doing so it triggered instability ahead of it, especially over southern Ghana, extending to Togo, leading to the formation of cells, which were two, over Central Togo.
These cells then moved southwards towards the sea. A massive moisture flow emanating from the sea at that time fed into what is known as a convergent zone along the Kwahu Ridge as well as the Akwapim ridge and the one over the Akwapim Ridge intensified and affected Accra.
He said the the Accra cell was so intense that it produced rainfall with an intensity of 32 millimeters per hour. This system moved along the coast but was very weak on reaching the Western Region.
Torgbui Gbegbie Fiamekor said earlier on a primary cell which developed from the vortex over Nigeria entered the sea and moved along Ghana’s coastal areas, adding that its northern fringes affected the coast.
“That is what prolonged the rain from Tuesday evening to Wednesday morning,” he said.
He said the country was not yet in the rainy season, adding that whilst the rainy season was expected to begin around February ending, the exact time of its start had not yet been determined.
Torgbui Gbegbie Fiamekor said the systems which had to be present to sustain the kind of rainfall that characterized the rainy season were absolutely absent at the moment.
“What we have now is the dry season rainfall, where dry and moist air, with the effect of heat in the atmosphere, interacts to form vortexes which raise moisture to form clouds,” he said.
Source: GNA