Met forecasts preliminary rains this week

The Department of Climate Change Management and Meteorological Services has forecast sporadic thundery showers, particularly over southern parts of the country, this week, triggering the preliminary rains locally known as chidzimalupsya.

According to the department, the chizimalupsya is expected from Friday, October 14 to Saturday, October 15.

The department said in a statement that the chizimalupsya will be followed by an outburst of moderate Mwera winds over Lake Malawi and a drop in day time temperatures.

In the week-long weather update released on Sunday, the department said that during October, chidzimalupsya do occur, triggered by the warming of the lower levels of the atmosphere and cooling of the middle levels of the atmosphere, technically called conditional instability.

“These are also triggered by the interaction of relatively warm and moist airflow from either the east or north east in the lower levels of the atmosphere with airflow from the west in the middle levels.

“The meeting of relatively warm and moist airflow from the north east with cool and most airflow from the south east meteorologically known as convergence ahead of pressure surge also triggers these sporadic thunderstorms [chidzimalupsya rains] which then merges with the main rainfall mainly in November,” reads in part the statement signed by the department’s director Jolamu Nkhokwe.

The statement added that the onset of the first rains is usually associated with strong winds, thunder and lightning due to accumulation of energy in the atmosphere caused by protracted heating from the sun.

The department has since warned that the thunderstorms and strong winds are likely to cause damages to infrastructure such as ripping off roofs from buildings, lightning strikes and hail stones.

Meanwhile, the 2016/17 rainfall season forecast released by the department last month indicated a higher probability for above normal rainfall amounts compared to previous years, which usually leads to floods.

The forecast said between October and December, the northern half of Malawi will have 40 percent chances for normal rainfall and 25 percent chances for above normal rainfall amounts.

It also said the southern half of Malawi will have a similar chance on normal rainfall, but increased chances for above normal rainfall of 35 percent. n