Seasonal Weather Assessment for Ethiopia during March – July 2016

Situation Report
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Ethiopia, broadly speaking has three seasons. The short rains season, known as the Belg, runs from February to May. This is then followed by the long rains season, known as the Kiremt, which is between June and mid September. The Bega, typically occurs between October and January, and is characterised by generally dry weather over the bulk of the country, with wet weather and a secondary peak in rainfall over the south.

Across southern and eastern parts of the country there is an increase in the probability of above-average rainfall during the Belg rains. Further north, there are no strong signals away from climatology. Heading into the Kiremt (i.e. beyond May) predictions are more uncertain, with both above- and below-average rainfall considered to be equally probable at this stage. More detailed information on the forthcoming Kiremt rains (June-September) may be possible in the coming months.

Forecast or trends for next 6 months

The strong, near record, El Niño event peaked in December 2015 and since then has been in decline.
Despite a reduction in sea surface temperatures in the eastern Pacific, El Niño is still strong and is likely to have wide reaching global impacts in the months ahead. By late spring or early summer, most seasonal predictions systems suggest near neutral conditions, with a chance of La Niña developing by the end of the year. As we head into the summer months the effect of El Niño on rainfall patterns across the globe is uncertain, with it being a decaying event.

Specifically, for Ethiopia the impact El Niño has on rainfall patterns varies across the country and through different seasons. Typically, across southern parts of the country El Niño increases the probability of aboveaverage rainfall during the Belg (Feb-May). In the Kiremt (Jun to Sep), below-average rainfall is more probable in El Niño years nationwide. However, with a transition to neutral conditions in the tropical Pacific through the coming months, the influence of the current El Niño on the Kiremt rains is uncertain.

Seasonal prediction systems from the Met Office GloSea5 system and from ECMWF, both suggest an increase in the probability of above-average rainfall across southern and eastern parts of Ethiopia. Further north predictions are more uncertain; both systems have very weak signals. On balance, near to belowaverage rainfall is thought to be most probable during the Belg. Forecasts for averages over long periods cannot provide details about short spells of weather during the period. Thus even in wetter-than-average seasons dry spells may still occur and lead to significant local impacts. As already noted, predictions for rainfall in the Kiremt are very uncertain and no useful information can be given at this time.

Predictions from the seasonal forecast systems, particularly across southern parts of the country, are consistent with our understating of how El Niño influences climate across the region.