GHACOF53 predicts wetter conditions for most of GHA for the October to December season

By Andrew Kaggwa and David Luganda, AFMC/NECJOGHA

Dar es Salaam, Tanzania – There is a higher chance of wetter conditions in most of the equatorial and southern sectors of the Greater Horn of Africa (GHA) during October to December 2019 but enhanced chances of drier than average conditions are indicated along the Red Sea areas of Sudan and Eritrea.

This is contained in a statement released by the IGAD Climate Prediction and Application Centre (ICPAC) at the end of the Fifty Third Greater Horn of Africa Climate Outlook Forum (GHACOF53) which took place at the Hyatt Regency Hotel in Dar es Salaam Tanzania from August 26 to August 28, 2019.

The Forum brought together climate information providers and users from key socio-economic sectors, governmental and non-governmental organisations, decision-makers, climate scientists, media and civil society stakeholders among others. 

The member States of The Intergovernmental Authority on Development (IGAD) are 8: Djibouti, Ethiopia, Eritrea, Kenya, Somalia, the Sudan, South Sudan and Uganda but Tanzania, Burundi and Rwanda are part of the GHA and covered in this forecast.

The statement says that the downscaled regional objective forecast was arrived at after analysis from 7 Global Producing Centres (GPCs) in the region.

Figure 1: Greater Horn of Africa Objective rainfall Outlook for the October to December 2019 rainfall season
Zone I: In this Zone the highest probability is for above normal rainfall (55%). The probabilities for normal
and below normal are 25% and 20% respectively.
Zone II: In this Zone the highest probability is for above normal (45%). The probabilities of normal and below
normal are 30% and 25% respectively.
Zone III: In this Zone the highest probability is for below normal (45%). The probabilities of normal and above normal are 35% and 20% respectively

“Enhanced chances of drier than average conditions are indicated along the Red Sea areas of Sudan and Eritrea. Raised chances of wetter conditions are indicated over northern Sudan and depressed rainfall in the northern Rift Valley of Ethiopia regions which rarely receive rainfall during the October- November- December (OND) season and this may indicate potential for occurrence of unseasonal rainfall,” it says.

The statement continues to note that while much of the equatorial sector is expected to experience wetter conditions during the OND season, the models predict increased likelihood of drier than average rainfall during September 2019 over south-eastern and north-eastern Ethiopia, eastern Kenya, southern Somalia, western Tanzania and central Sudan.

An earlier than normal start of the rains is indicated across the western sector including Tanzania, Burundi, Rwanda, Uganda, and western Kenya. On the other hand, moderately delayed onset is indicated over eastern Kenya, Somalia, and south-eastern Ethiopia.

Analysis of predicted dry spells in the first 20 days after onset indicates that such spells will generally be short, with only a few consecutive dry days over much of the equatorial sector; however over eastern Kenya, Somalia, and southeastern Ethiopia dry spells of more than 10 days are anticipated.

As for the temperature forecast, the statement says that, the regional objective climate temperature outlook for OND 2019 season indicates increased likelihood of above average temperature over much of the region. In particular, eastern Tanzania, eastern Kenya, much of Ethiopia, Somalia, Eritrea and Sudan are anticipated to have increased likelihood of warmer than average temperature, while western Tanzania, Burundi, Rwanda, eastern Uganda, south-eastern South Sudan, and southwestern Ethiopia are indicated to experience near average temperatures.

Figure 2: GHA Mean Surface Temperature Outlook for October to December 2019
Zone I: Increased likelihood of above normal (i.e., warmer) mean temperatures. The probabilities shown in Zone
1 (above = 70%; normal = 20%; below = 10%) are valid for the corresponding shading interval (dark
orange). Elsewhere, where shading indicates the probability for above normal is higher (red)/lower
(light orange or yellow) than 70%, the probabilities of normal and below normal will be proportionately
lower/higher than 20/10%.
Zone II: Increased likelihood of near normal mean temperatures.

After this, the National Meteorological and Hydrological Services (NMHSs) of the individual countries are to immediately downscale this forecast to highlight local factors. The Uganda National Meteorological Authority (UNMA) has confirmed September 4^th, 2019 as the date when it will release its downscaled forecast for the September-October-November-December (SOND) seasonal weather forecast.

Full GHACOF53 statement here

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