Tropical Lows in Southern Africa

• Cloud Structure In Satellite Images
• Meteorological Physical Background
• Key Parameters
• Typical Appearance In Vertical Cross Sections
• Weather Events
• References

Weather Events

Significant weather events associated with tropical weather systems over the continent of Africa is predominantly heavy rainfall.

ITCZ over the ocean

Parameter	Description
Precipitation	Band of clouds consisting of showers, with occasional thunderstorms, that encircles the globe near the equator. The tendency for convective storms in the tropics is to be short in their duration, usually on a small scale but can produce intense rainfall. http://www.srh.noaa.gov/jetstream/tropics/itcz.htm
Wind (incl. gusts)	Weak winds known as the doldrums. When convective squall lines develop the storm may be associated with strong gust fronts.
Lightning	Cumulonimbus clouds over oceanic areas may not actually produce any significant thunder or lightning Even the tallest towers with ample instability might not produce any lightning. http://www.weatherwise.org/Archives/Back%20Issues/2009/Nov-Dec%202009/full-Intertropical-Converge.html

ITCZ over the Continent

Parameter	Description
Precipitation	Organized bands of rain. Showers The sheer depth of the troposphere in the tropics allows the highest cloud tops to reach 50,000 ft and sometimes even more than 70,000 ft MSL. http://www.weatherwise.org/Archives/Back%20Issues/2009/Nov-Dec%202009/full-Intertropical-Converge.html
Wind (incl. gusts)	Gust fronts if the convection orginizes into squall lines or MCS When convective squall lines develop the storm may be associated with strong gust fronts.
Lightning	The seasonal motion of peak lightning over tropical Africa has the same phase as the migration of the ITCZ but that there is no precise space-time coincidence. It is also shown that over shorter time scales the tropical band of lightning activity does not simply follow the Sun nor does it adhere to the ITCZ. What emerges is a complex pattern of behavior which, though clearly influenced by solar declination and the ITCZ, is also determined by the underlying terrain and humidity. It is sometimes considered that lightning in the tropics would be a good locator of the ITCZ, but it is not the case. (Collier and Hughes, 2011)

Easterly lows

Parameter	Description
Precipitation	Due to the low wind shear environments in which these storms develop they are very slow moving and may therefor result in very heavy rainfall and flooding.
Lightning	The number of lightning strikes varies between 40-80 thousand strikes per MCS.
Other relevant information	Easterly waves are also associated with tropical cyclone formation, especially over the tropical Atlantic.

Continental tropical lows

Parameter

Description

Precipitation

Its major weather hazard is heavy rainfall to the east of the low. As these systems are associated with weak vertical wind shear and very light steering winds in the mid troposphere the convective cells which develop from them is semi-stationary making them extreme precipitation efficient. Many flood events over southern Africa has been associated with CTL. MITS provide indication of the areas where heavy rainfall can develop.