PROSPECTS FOR THE 2022/2023 RAINFALL SEASON IN MALAWI
BOTTOM LINE: Generally, normal to above-normal rainfall amounts are expected over most parts of Malawi
The period October to April is the main rainfall season over Malawi. October therefore marks the beginning of the official monitoring of rainfall season in the country. But the main rains are usually experienced from November starting from the south and progressively spreading to central and northern areas. However, pre-season rains locally known as Chizimalupsya are experienced at the beginning of the season.
The main rain bearing systems that influence rainfall over Malawi include the Inter-tropical convergence zone, Congo air mass, easterly waves and tropical cyclones. Key driving factors of these rain bearing systems include mean sea level pressure, upper-level winds and sea surface temperatures over the tropical Pacific, Indian and Atlantic Oceans.
Global climate models are projecting La Nina conditions during the better part of 2022/2023 rainfall season. La Nina phenomenon is unusual cooling of waters over the Eastern Central Equatorial Pacific Ocean and is known to enhance rains over Southern Africa which may include southern Malawi while suppressing rains over Eastern Africa which may include northern part of Malawi. Past rainfall seasons that experienced La Nina conditions similar to the current La Nina projections are: 1995/96, 2000/01, 2011/12, 2017/18 and 2020/21. Climate analyses on these analog years show that the country had normal onset with isolated delayed onset over the south, normal cessation of rains, and generally normal total rainfall amounts.
The analyses and forecasts from climate experts in Malawi, with additional inputs from Southern African region’s climate experts meeting that preceded the 26th Southern Africa Regional Climate Outlook Forum held virtually from 15th to 26th August 2022, indicate that:
- During the period October to December 2022, normal to above-normal total rainfall amounts are expected over most areas of the country. However, there is high chance of below normal rainfall amounts in the month of December mainly over the central and northern areas of Malawi.
- During the period January to March 2023, normal to above-normal total rainfall amounts are expected over most areas, with some pockets of below normal likely over the south eastern and central areas of Malawi.
The forecast implies that during the 2022/2023 rainfall season, there is a high chance of many parts of the country receiving good rainfall amounts. However, extreme weather events such as heavy rains leading to floods are likely to occur in prone areas while some parts of the country may experience pockets of prolonged dry spells during the season.
This forecast is relevant for relatively large areas and seasonal time scales and therefore may not account for all factors that influence localized climate variability, such as daily and weekly variations. To account for local the factors, downscaled district forecasts have been produced and in addition, seasonal updates, ten-day agrometeorological bulletins, weekly forecasts, five-day and daily forecasts will be continuously issued. Warnings and advisories on extreme weather events including tropical cyclones will also be issued during the season. For additional information on the possible monthly distribution, monthly total rainfall amount probabilities are presented in detailed forecast.
In applying this forecast, users from different sectors such as Agriculture, Disaster Management, Energy and Water are encouraged to seek advice from the relevant ministries.
For further information and interpretation of this seasonal forecast, users are advised to contact the Director of Climate Change and Meteorological Services, P.O. Box 1808, Blantyre; E-mail: metdept@metmalawi.com; Tel: (265) 1 822014; Fax: (265) 1 822215. Website: www.metmalawi.gov.mw
The maps above are the forecast maps for the 2022/2023 rainfall outlook which covers the period October to December (OND) 2022, and January to March (JFM) 2023 presented in the form of probabilities of occurrence of rainfall amounts:
In Map A, the greater part of Malawi has 40% probability of rainfall amounts occurring in the normal category; a 35% probability in the normal category; and a 25% probability in the below-normal category, implying normal to above-normal total rainfall amounts are expected over most areas, with likelihood of below normal over few areas.
In Map B, there is a 40% probability of rainfall amounts occurring in the normal category for most areas; a 35% probability of rainfall amounts occurring in the above-normal category for some areas in northern and southern Malawi; and a 25% probability in the below-normal category. This implies normal to above-normal total rainfall amounts are expected over most areas with pockets of dry spells in some areas.
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Director of Climate Change and Meteorological ServicesMinistry of Natural Resources and Climate Change
Blantyre
Date of issue: Thursday, 15th September, 2022.