CAPACITY BUILDING WORKSHOP CONSENSUS CLIMATE OUTLOOK FOR THE GREATER HORN OF AFRICA FOR THE PERIOD JUNE – SEPTEMBER 2001
SUMMARY
During
the months of June to September, most of the rainfall is usually concentrated
to the northern sector of the sub region. Substantial rainfall is also
received in the coastal and western equatorial parts of the sub region.
The outlook for June to September 2001 season shows that there is increased
likelihood of near to below normal rainfall over much of the Greater Horn
of Africa sub region. However there is increased likelihood for near to
above normal rainfall over the northeastern parts of the sub region.
THE
CAPACITY BUILDING WORKSHOP
From 14 to 26 May 2001, a regional capacity building workshop was organised by the Drought Monitoring Centre Nairobi (DMCN), a specialized institution of IGAD, in order to develop seasonal climate outlook for the northern sector of Greater Horn of African sub-region for the period June – September 2001. The workshop was held within the frame work of the USAID funded project “Applications of meteorology to the reduction of climate and weather related risks to food security, water resources and health for sustainable development in the Greater Horn of Africa sub-region”. NOAA/Office of Global programs is also supporting some user pilot applications projects in the sub region.
The
workshop participants included representatives from Meteorological Services
of six countries in the Greater Horn of Africa sub-region that receive
substantial rainfall during June to September season. They are Sudan Meteorological
Authority; Djibouti Meteorological Department; Meteorological and Hydrological
Service of Eritrea; National Meteorological Service Agency, Ethiopia; Kenya
Meteorological Department; and Uganda Meteorological Department. The Kenya
Meteorological Department, University of Nairobi/Department of Meteorology
and the Drought Monitoring Centre, Nairobi, provided technical support
to the workshop.
METHODOLOGY
The workshop reviewed the state of the global climate system and its implications for this region. Among the principal factors taken into account were the evolution patterns of the sea-surface temperature anomalies over various parts of the global Oceans. The prevailing and projected sea-surface temperature anomalies (SSTs) over the Indian and Atlantic oceans including the recent development of the zonal and meridional SST gradients were also considered. These and other factors affecting the climate of the Greater Horn of Africa sub-region were assessed using various statistical methods. Products from coupled ocean-atmosphere models and physically based statistical models from several major climate centres were further considered in the development of the workshop consensus climate outlook. The centres whose products were utilized include the International Research Institute for climate prediction (IRI); National Oceanic and Atmospheric Administration/National Centers for Environmental Prediction (NOAA/NCEP); European Centre for Medium Range Weather Forecasts (ECMWF) and United Kingdom Meteorological Office. The workshop participants established consensus probability distributions to indicate the likelihood of below-, near- or above-normal rainfall for each zone (see Map). Below-normal rainfall is defined as within the driest third of recorded rainfall amounts in each region; near-normal is the third centred around the climatological median; above-normal rainfall is defined as within the wettest third of rainfall amounts. In cases where climatology is indicated[33 in all boxes], no skillful forecast information could be provided.
The
current status of seasonal-to-interannual forecasting allows prediction
of spatial and temporal averages, and may not fully account for all factors
that influence regional and national climate variability.Most of the current
methods used at the DMCN are statistically based. Efforts are being made
to develop climate-modeling capacity through support from IRI, WMO and
other partners.
OUTLOOK
June to September is the major rainfall season over much of the northern sector of Greater Horn of Africa sub-region including Ethiopia, Sudan, Eritrea and Djibouti. Substantial rainfall is also received over the coastal and western equatorial parts of the sub region during the same period.
The outlook for June to September 2001 indicates increased likelihood of near normal to above normal over northeastern Ethiopia and extreme northern Somalia. Much of Sudan, western and northern Ethiopia, southwestern and northern Ethiopia and Djibouti have high likelihood of experiencing below normal to near normal rainfall. The March to May rainfall over the coastal and western equatorial sector of the sub region is expected to extend into the June to August season. The consensus climate outlook indicates high likelihood of near normal to below normal rainfall over much of Uganda and coastal and western Kenya. Climatology is indicated over northern Sudan, northwestern and eastern Eritrea, much of Somalia, much of Kenya, Tanzania, Rwanda and Burundi.
This Outlook is relevant only to seasonal time scales and relatively large areas; local and month-to-month variations may occur. Users are strongly advised to contact the respective National Meteorological Services for interpretation of this Outlook and for updates and additional guidance.