CLIMATE OUTLOOK FOR MARCH – MAY, 2014 RAINFALL SEASON

Our ref: TMA/1622                                                                           27^thFebruary, 2014

This statement gives a review of the performance of the October to December (OND), 2013 short rainfall season, the ongoing seasonal rains over central, western, southwestern highlands, southern region and southern coast, and an outlook for the March to May (MAM), 2014 long rainfall season (Masika).

During the October to December 2013 short rains (Vuli), most parts of the country featured normal rainfall. However, some parts of the coastal and central areas experienced below normal rainfall. Generally, the season was characterized by poor temporal and spatial rainfall distribution particularly over much of bimodal areas. During January and February, 2014 forecasted severe weather events such as strong winds and heavy rains that resulted into loss of life and properties over few parts of the country were observed. The spatial distribution of the rains in January and February 2014 was generally good over unimodal areas. During the same period, bimodal areas experienced episodes of off-seasonal rains.

The outlook for the March to May, 2014 rainfall season indicates that most parts of the bimodal areas (Lake Victoria Basin, northeastern highlands and northern coast) are likely to receive normal to above normal rains over most parts except for northern coastal  areas where below normal rains are anticipated.   Ongoing seasonal rains over the unimodal areas are likely to be normal to above normal.

The principal contributing climate factors to the MAM 2014 seasonal rainfall are the westerly wind anomalies over most parts of the country particularly in the month of March and April 2014 thus enhancing moisture intrusion from CongoBasin. The predominant westerly wind flow as a result of cooler Sea Surface Temperatures condition over eastern Atlantic Oceanis likely to be sustained throughout the season. Warming condition off the southern tip of Africa is expected to suppress rainfall over the coastal areas of the country.

During the October to December 2013 short rains (Vuli), most parts of the country featured normal rainfall. However, some parts of the coastal and central areas experienced below normal rainfall. Generally the season was characterized by poor temporal and spatial rainfall distribution particularly over much of Northeastern highlands and northern coast areas (Manyara, Arusha, Kilimanjaro, Dar es salaam) and Musoma over the Lake VictoriaBasin. Moreover the rains were preceded by unusual late onset as predicted over Dar es Salaam, Kilimanjaro, Arusha and Manyara regions.  During November to December, 2013 onset and distribution of rains over Kigoma, Katavi, Rukwa, Mbeya, Iringa, Njombe and Ruvuma were generally good. However, over central areas (Dodomaand Singida) the rains started late and were below normal during the period. During January and February, 2014, most of the bimodal areas including northern Morogoro, Kilimanjaro, Arusha, Manyara, Dar es Salaam, Coast and Shinyanga received significant off seasonal rains. The heavy rains associated with strong winds and floods resulted into loss of lives and destruction of properties and infrastructure over some areas including Same, Mwanga, Hai and Kilosa districts.

The recorded rainfall during October to December 2013 for some selected stations with their respective percentages of long term means in brackets are indicated below:

Northern Coast and hinterlands: Matangatuani recorded 390.1 mm (81%), Pemba 159.4 mm (57.9%), Amani 573.9 mm (110.9%), JNIA 184.6 mm (59.0%),  Zanzibar 338.9 mm (53.2%) and Morogoro 151.3mm (77.0%) of rainfall.

Northeastern highlands: Moshi recorded 124.6 mm (89.4%), Arusha 222.8 mm (103.1%), Lyamungo 195.9 mm (91.8%), Same 130.0 mm (78.6%) and KIA 129.3 mm (118.3%) of rainfall.

Lake VictoriaBasin: Mwanza recorded 365.4 mm (95.8%), Bukoba 501.5 mm (90.4%), Musoma 154.4 mm (63.4%) and Shinyanga 274.7 mm (93.9%) of rainfall. 

Western areas: Tabora recorded 394.3 mm (115.2%), Kibondo 369.4 mm (92.5%), Tumbi 361.8 mm (107.5%) and Kigoma 440.3 mm (113.7%) of rainfall.

Central areas: Dodomarecorded 88.5 mm (58.4%), Hombolo 68.2 mm (40.7%) and Singida 135.3 mm (63.9%) of rainfall.

Southwestern highlands: Iringa recorded 77.9 mm (53.0%), Mbeya 228.2 mm (87.5%), Tukuyu 386.7 mm (87.1%), Sumbawanga 273.0 mm (91.0%), Mahenge 536.3 mm (109.1%) and Igeri 345.4 mm (104.9%) of rainfall.

Southern areas: Mtwara recorded 149.8 mm (62.9%), Naliendele 117.8 mm (43.6%)  Kilwa 58.6 mm (24.6%) and Songea 298.2 mm (124.7%) of rainfall.

This outlook is based on a review of the current and expected state of global climate systems and their likely impacts on the upcoming March to May (MAM), 2014 rainfall season in the country.

Currently, the Sea Surface Temperatures (SSTs) indicate anomalous warming condition over the Southwestern Indian Ocean and expected to gradually increase throughout the season. Meanwhile, near normal developing into slightly warm SSTs condition over western Indian and equatorial PacificOceans are expected during the season. On the other hand, cooling condition over eastern Atlantic Ocean are likely to be sustained throughout the season. These conditions are likely to favor enhanced westerly winds over western and central parts of the country particularly during the months of April to May, 2014 thus enhancing moisture inflow from the CongoBasin.

Current anomalous warming condition off the southern tip of Africa is expected to continue during March to May 2014 thus likely to weaken the southern high pressure systems. These conditions suggest the possibility of diffused Inter-Tropical Convergence Zone (ITCZ)   over the coastal areas of the country leading to suppressed rainfall. However, towards the end of the season and beyond, enhanced easterly winds are likely to influence enhanced occasional rains over the coastal areas.

The long rainfall season in the northern sector (bimodal areas) of Tanzania is due to commence in the first weekof March, 2014. The details are as follows:

Lake Victoriabasin: Mwanza, Mara, Geita, Shinyanga, Simiyu and Kagera regions: Rains are expected to start in the first weekof March, 2014 in Kagera and Geita regions and gradually spreading to Mwanza, Mara, Shinyanga and Simiyu regions in the second week of March. Rains in these areas are likely to be above normal except over eastern parts of Mara where normal to above normal rains are expected.

Northern coast and hinterlands (Dar es Salaam, Tanga, Coast, northern part of Morogoro regions and isles of Unguja and Pemba): Rains are expected to start during the second and third week of March, 2014. The Masika rains over much of these areas are likely to be below normal and poorly distributed.  However, most parts of Morogoro region are likely to experience normal to above normal rainfall.

Northeastern highlands (Kilimanjaro, Arusha and Manyara regions): The onset of rainfall is expected during thesecond to third week of March, 2014 and the rains are likely to be normal to above normal over much of these areas except for some parts of Kilimanjaro region (Same district and surrounding areas) where below normal rains are likely to occur.

Western areas (Kigoma, Tabora and Katavi regions):The ongoing seasonal rains over these areas are expected to be mainly normal with pockets of above normal over northeastern parts of Tabora region. These rains are expected to recede during the fourth week of April, 2014.

Central areas (Singida and Dodoma regions): The ongoing seasonal rains are likely to be normal to above normal. These rains are expected to recede during the second week of April, 2014.

Southern coastal areas (Mtwara and Lindi regions): The ongoing seasonal rains are likely to be normal to above normal except for northeastern parts of Lindi where below normal rains are expected. Cessation of rains is expected during the third week of April, 2014.

Southern areas (Ruvuma): The ongoing seasonal rains in these areas are likely to be normal to above normal. Cessation of the rains is expected during the third week of April, 2014.

Southwestern highland areas (Mbeya, Iringa, Njombe, Rukwa and southern part of Morogoro regions): The ongoing seasonal rains in most of these areas are likely to be normal to above normal except for Njombe region where above normal rains are expected. These rains are expected to end during the first week of May, 2014.

Sufficient soil moisture is expected over most areas of the country except along the Coast, Unguja and Pembaisles and few areas of the northeastern highlands  where soil moisture deficit is likely to occur. Areas over the Lake Victoria basin (Kagera, Geita, Mwanza, Shinyanga, Simiyu and Mara regions) together with Morogoro region, farmers are advised to continue with their normal agricultural activities. However, above normal rains are likely to produce excessive soil moisture conditions which can impede crop production, therefore farmers are encouraged to seek advise from extension officers in their respective areas.

Over the northern coast (Dar es Salaam, Pwani and Tanga regions including Unguja and Pemba isles) and north eastern highlands (Manyara, Arusha and Kilimanjaro regions), farmers are advised to plant drought tolerant and early maturing crops.  On the other hand, sufficient soil moisture is expected  over unimodal areas (Kigoma, Tabora, Rukwa, Katavi, Dodoma, Iringa, Lindi, and Mtwara together with southern parts of Morogoro region); farmers are advised to continue with their normal cropping season activities and to salvage the remaining part of the season. However, above normal rains over some areas (Singida, Mbeya, Njombe and Ruvuma regions), are likely to cause excessive soil moisture which can affect crops at  maturity and harvesting  therefore farmers are advised to take necessary precautions.

In areas where above normal rains are expected, water levels over the lakes, dams and river flow discharge are expected to increase during March to May, 2014  rainfall season. Moreover, it is advised that water harvesting systems and storage structures  be improved to stock the excess water during the season. Areas with below normal rains, water harvesting and storage techniques are encouraged.

Pasture and water availability for livestock and wildlife are likely to be good over most areas of the country except along the coastal areas where below normal rains are expected.  Areas expected to receive below normal rains, pastoralists and agro-pastoralists are advised to harvest and conserve pasture for use during dry season. However, pastoralists and agro-pastoralists are strongly encouraged to seek more advice from livestock extension officers.  On the other hand, areas expected to receive normal to above normal rains are likely to have improved biodiversity, plant flowering, honey/wax production and reduced animal migration thus expected to reduce human wildlife conflicts.

During the March to May 2014, rainfall season episodes of heavy rains are expected to occur and may result into disasters. Therefore, Municipals are advised to take precautions including open up and clear of  drainage systems to avoid water accumulation due to surface runoffs so as to reduce the impacts of heavy rains that may result into floods.  Same precautions should be taken for Areas expected to receive normal and below normal rains (coastal belt and some areas of the north eastern highlands), due to the fact that there is likelihood of heavy rain fall  episodes.

In areas where above and below normal rains are expected, there is a likelihood of waterborne and water related diseases such as malaria, trachoma and cholera thus necessary precautions should be taken by communities and the responsible authorities.

Socio-economic sectors are advised to proper utilize March to May, 2014 rainfall outlook in their daily activities and during the implementation of National Development Plan in order to reduce risk that may occur.

Disaster management authorities and other stakeholders are advised to take necessary measures that would ensure preparedness, response, and mitigation of any negative impacts resulting from the expected weather and climate conditions.