The onset of the rainy season in The Gambia is defined using criteria as first fall (1st May) amounting to 20 millimetre or more in one or two consecutive days that is not followed by a dry spell of 10 days in the next 30 days, says Fatou Sima, a meteorologist and head of the Climate Unit at the Department of Water Resources (DWR).

This fact, Sima said, indicates that the 18th May rains that Gambia experienced is not the actual onset of this year’s cropping season, hence a good 14 days dry spell occurred since that first rains.

Speaking to the Daily Observer on Thursday at her office, she said the analysis of her department indicated that the onset of rains in The Gambia is expected around June in the West Coast Region (WCR). “We always base the onset of rains to advise farmers on the right time to commence growing their crops,” she explained.

According to her, rainfall results are usually expressed as being either below normal or normal or above normal with normal rainfall defined as the average rainfall during a 30-year period.

2012 wet season climate forecast

According to results of this year’s wet season climate forecast which was prepared by the Department of Water Resources in collaboration with the National Meteorological Services within the sub-region and beyond, it is indicated that it must be noted that seasonal forecasting relies on prediction of averages over space and time and may not reflect all the various factors that influence regional and national climate differences.

Accordingly, it indicates that the forecast is relevant only for the entire season and within relatively large areas, since local and month-to-month variations may occur. Consequently, the forecast indicated that for the rainy season July, August and September (JAS) 2012, the forecast is one of normal (most likely) to below normal rainfall (likely), that a threshold of at least 690 millimetres of rainfall in The Gambia.

As at now, the forecast is based on the best estimate of the impact of the various factors affecting rainfall in the country, and would be updated on a monthly basis starting from the end of June 2012. The forecast further indicated that it is worthy of note that the 2012 rainfall season is expected to undergo more variability with events such as late onset and disruption in the distribution of rain.

Accordingly, the Department of Water Resources will undertake to provide decadal climate and short to medium range weather forecast to better anticipate impacts of intra-seasonal climate events. It is also indicated that the forecast is highly recommended for use in the planning of interventions in several socio-economic sectors.