Zimbabwe + 7 more

Seasonal rainfall outlook for SADC countries Apr - Jun 2002


HIGHLIGHTS

Significantly below-normal rainfall affected most of Botswana and western Zimbabwe from the month of December to February.

Rain continues in the northeastern sector.

Normal to above normal rainfall is expected for northern sector and Island States.

Central parts of the subregion expects normal to below normal as the rainy season terminates.

SUMMARY OF DECEMBER 2001 - FEBRUARY 2002 RAINFALL PERFORMANCE

Most of the southern parts of SADC region had prolonged dry spells recording only below 300mm for the three months, December to February, Fig. 1(a). The remainder of the region received between 300 to 500mm with northern Mozambique, Malawi and most of Tanzania getting well above 500mm.

Meanwhile, the percentage of normal rainfall indicates that most of SADC region had normal to above-normal rainfall except for western Zimbabwe, most of Botswana, southeast Namibia and northeastern South Africa, which had only 65% of normal rainfall, Fig. 1(b) .

During April the rainfall season across most of the subregion draws to a close. This period is characterized by the northward shift of the ITCZ, the strengthening of the sub-tropical highs and their gradual northward movement. Thus most of the region is expected to receive only about 100 mm, Fig. 2 .

In contrast, the northern parts including Seychelles which has a bi-modal rainfall pattern starts to experience the second phase of the rainfall season. These areas receive between 200 to above 500mm. Mauritius also receives between 300 to 400mm mainly due to tropical cyclone activity.

RAINFALL OUTLOOK (APRIL - JUNE 2002)

Forecast Details:

Zone I: (Northwestern half of Angola, most of DRC, Mozambique and Tanzania)

Normal to above normal rainfall.

Zone II: (Zambia, Zimbabwe, Malawi, south eastern Angola, Botswana, most of Namibia and northern South Africa)

Below-normal to normal rainfall.

Zone III: (Southwest Namibia, Lesotho, Swaziland and southern South Africa)

Normal to above normal rainfall.

Map Caption

The numbers for each zone indicate the probabilities of rainfall in each of the three categories: above- normal, normal and below normal (Fig. 3) . The top number indicates the probability of rainfall occurring in the above-normal category, the middle number for normal, and the bottom for the below normal. For example, in the case of Zone IV (Mauritius) there is a 30% probability for rainfall occurring in the above-normal category; a 45% probability for rainfall in the normal category; and a 25% probability for a below normal category. It is emphasized that boundaries between Zones should be considered as transition zones.

N.B

This update is relevant only for three-monthly time scales and relatively large areas. Local to month-to-month variations may occur due to any changes in the projected patterns of, for instance, Sea Surface temperatures (SSTS) and other indicators.

The users are strongly advised to contact their NMSs for interpretation of this Outlook, finer details, updates and additional guidance.