Regional Climate Summaries: European Heat Wave
Regional Climate Summaries: Indian Summer Monsoon
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During the 1994 rainy season (May - September) rainfall totals in the Sahel were among the largest recorded in the past 30 years and were more than 120% of normal in many areas. In the western Sahel, 1994 precipitation ranked in the 60th percentile relative to the 1951-1980 base period (Fig. 4.16, top) and was the wettest year since 1967. However, relative to the 1961-1990 base period, precipitation ranked in the 70th percentile (Fig. 4.16, bottom) and was comparable in magnitude to the 1988 and 1989 seasons. Thus, changing the base period results in an apparent weakening of the prolonged 25-30 year drought. [We present both time series in this assessment in order to provide continuity with previous assessments and to demonstrate the effects of changing base periods on the interpretation of time series which contain substantial interdecadal variability. All other time series in this assessment are now based on normals for the 1961-1990 base period.]
Above-normal precipitation during 1994 was most prominent over the western half of the Sahel, and over parts of the Sudan and Ethiopia (Fig. 4.17). Additionally, over 1,000 mm of precipitation was recorded on the Ethiopian highlands and in large areas from 11oN southward to the Equator (Fig. 4.18). In most areas, these totals were sufficient to meet agricultural and hydrological needs. However, drought conditions continued during 1994 in countries south of the western Sahel along the Gulf of Guinea coast, where generally less than 80% of normal seasonal rains fell (Fig. 4.17).
The onset of precipitation in May varied across the Sahel. Well above-normal totals covered most of the western Sahel and parts of the Sudan. Near-normal to below-normal totals were measured in most areas south of 10N, and little to no rain fell on the extreme northwestern part of the region.
During June near-normal to above-normal rainfall covered much of the Sahel, with most areas south of 12oN recording more than 200 mm of rain. This rainfall alleviated immediate famine concerns through much of northeastern Africa.
In July and August, significant rains reached exceptionally far north (past 20N) in central parts of the depicted region, and heavy rains (100-400 mm) drenched most areas of the central and southern Sahel. In contrast, significantly below-normal totals were again observed south of the western Sahel.
In September, abnormally heavy late-season rains of 10-100 mm were reported over most of the Sahel, except in extreme western areas. Exceptionally heavy rains (100 - 400 mm) fell on the central and southern Sahel. Convective complexes continued to track unusually far north into typically dry areas of Mali and Niger during the month, with sporadic localized floods continuing to plague portions of Niger. Rainfall totals across the western Sahel during August and September were similar to totals recorded during the 1950s and early 1960s, with the amounts ranking near the 75th percentile (Fig. 4.19). In contrast, below-normal precipitation again covered areas south of the western Sahel along the Gulf of Guinea coast. Drier conditions finally arrived in the Sahel in October. However, occasional heavy rains persisted unseasonably far north, with new October rainfall records established in southeastern Mauritania, and destructive flooding reported in the Sudan.
Regional Climate Summaries: European Heat Wave
Regional Climate Summaries: Indian Summer Monsoon
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