Ref. No. KMD/FCST/4-2017/MO/12 Date: 29 November, 2017 REVIEW OF THE WEATHER IN NOVEMBER AND THE OUTLOOK FOR DECEMBER 2017

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1 REPUBLIC OF KENYA MINISTRY OF ENVIRONMENT & NATURAL RESOURCES KENYA METEOROLOGICAL DEPARTMENT Dagoretti Corner, Ngong Road, P. O. Box 30259, GPO, Nairobi, Kenya Telephone: 254 (0) , Fax: 254 (0) / / , Website: Ref. No. KMD/FCST/4-2017/MO/12 Date: 29 November, 2017 REVIEW OF THE WEATHER IN NOVEMBER AND THE OUTLOOK FOR DECEMBER SUMMARY Near-average to above-average (generally enhanced) rainfall was recorded over most parts of the country during the month of November (the rainfall peak month) Several meteorological stations in the country recorded near-average rainfall (between 75 and 125 percent) of their November Long-Term Means (LTMs). Stations like Wajir, Marsabit, Mombasa, Malindi, Mtwapa, Moyale, Nyeri, Meru, Thika, Dagoretti Corner, Msabaha and Lodwar, however, recorded aboveaverage (more than 125 percent) rainfall. The rainfall distribution, both in time and space, was generally good over most parts of the country especially during the first half of the month. The outlook for December 2017 indicates that most parts of the country will experience depressed rainfall during the month. Most of the Northeastern and Northwestern parts of the country are likely to experience generally sunny and dry weather conditions for most of December. The rainfall distribution, both in time and space, is expected to be generally poor especially over the eastern sector of the country. The October-November-December (OND) 2017 seasonal rainfall is expected to cease during the first week of December over the northern parts of the country. The cessation over the Central and parts of Southeastern Kenya is expected during the second to third week of December while the western region and parts of South Eastern Kenya will experience the cessation during the third to fourth week of December. 2. WEATHER REVIEW FOR NOVEMBER 2017 The November 2017 rainfall analysis indicates that the performance was quite good over the better part of the country. This was more so over the northern parts of the country, the coastal region and several parts of central Kenya. Most meteorological stations recorded rainfall that was in excess of their November LTMs. Wajir station, for example, recorded 276 percent of its LTM while Marsabit station recorded 199 percent. Other station that recorded more than 125 percent of their LTMs include Mombasa, Malindi, Mtwapa, Moyale, Nyeri, Meru, Thika, Dagoretti Corner, Msabaha and Lodwar. A few rainfall storms were recorded at the beginning of the month with some stations recording very high daily rainfall amounts. Kwale rainfall station recorded 162mm on 1 st November while Meru, Kerugoya and Marsabit stations recorded 92.5mm (on 6 th ), 125mm (on 4 th ) and 137.4mm (on 1 st ) respectively. In terms of monthly rainfall totals, Meru station recorded the highest amount of 482.3mm, followed by Marsabit mm, Thika mm, Embu mm, Dagoretti Corner mm, Wajir - 1

2 205.0mm and Mombasa 204.5mm. Mtwapa, Nyeri, Machakos, Moi Airbase, Kericho and Moyale recorded between 150 and 200mm while the rest of the stations recorded less than 150 mm. The lowest percentage of just 41% was recorded at Garissa station. Figure 1a shows the total rainfall amount recorded in November (red bars) as compared to the November LTMs (blue bars), while figure 1b shows the spatial rainfall distribution as a percentage of the November LTMs. 3. REVIEW OF THE OCTOBER-NOVEMBER-DECEMBER (OND) 2017 The seasonal rainfall analysis from 1 st October to 30 th November 2017 indicates enhanced rainfall was recorded over several parts of the country. Quite a number of stations had achieved their LTMs for the season by the end of November as a result of the highly enhanced rainfall recorded during the month of November. However, a few stations in southeastern and western Kenya as well as Coast strip and Garissa County were yet to achieve their seasonal LTMs. Makindu, Lamu, Garissa and Voi stations, for example, had recorded just 40%, 36%, 24% and 23% of their seasonal LTMs respectively The highest seasonal amount of 640.7mm was recorded at Meru station. Embu, Dagoretti Corner, Thika, Kisii, Eldoret Airport, Marsabit and Kericho stations recorded 458.2mm, 386.7mm and 383.5mm, 372.4mm, 362.7mm, 327.7mm and 314.2mm respectively. The rest of the stations recorded less than 300mm. Lodwar, Voi, Lamu and Garissa stations recorded less than 100mm. Figure 2a shows the total rainfall amount recorded in October-November (red bars) as compared to the OND LTMs (blue bars), while figure 2b shows the October-November spatial rainfall distribution as a percentage of the OND LTMs. 4. THE PREVAILING GLOBAL SEA SURFACE TEMPERATURES (SSTs) CONDITIONS Cooler than average to near average Sea Surface Temperatures (SSTs) were observed over the eastern and central equatorial Pacific Ocean (the Niño areas) while warmer than average SSTs prevailed over western equatorial Pacific Ocean. This was an indication that La Niña-like conditions were present in the Pacific Ocean. Various models forecasted an increased likelihood of Negative ENSO towards the end of the year Near average to cooler than average SSTs were dominant over eastern equatorial Indian Ocean with much of the central to western equatorial Indian Ocean experiencing warmer to near average SSTs. 5. EXPERIENCED IMPACTS DURING OCTOBER AND NOVEMBER 2017 The good rainfall performance over most parts of the country resulted into good crop performance over most agricultural areas of the country. The heavy recorded in the catchment areas of the sevenfolks hydroelectric dams result into good inflows and increased water levels in the dams. A few cases of flooding were reported especially in the Coastal region due to heavy rainfall recorded within short periods of time. 6. FORECAST FOR DECEMBER 2017 This climate outlook for December 2017 is mainly based on the prevailing and expected Sea Surface Temperature Anomalies (SSTAs) over the Pacific, Indian and Atlantic Oceans. The current near-neutral conditions in the Pacific Ocean and the neutral Indian Ocean Dipole were highly considered. The predicted Cessation and distribution of rainfall were derived from statistical analysis of past years, which exhibited similar characteristics to the current year. The forecast indicates that most of the country is likely to experience depressed rainfall during the month of December 2017 as depicted in figure 3. The rainfall distribution, both in time and space, is expected to be generally poor especially over the Northern and Eastern sector where generally sunny and dry weather conditions are likely to prevail during the month. The specific outlook for individual areas is as follows: 2

3 The Highlands West of the Rift Valley (Kericho, Nandi, Kakamega) and the Lake Basin (Kisii, Kisumu, Busia) are likely to receive near-average rainfall with a slight tendency to above-average (slightly enhanced) rainfall. The North-Rift (Eldoret, Kitale), Central Rift Valley (Nakuru, Narok, Kajiado), Central Highlands (Nyeri, Muranga, Nyandarua, Kiambu, Embu, Meru, Nanyuki), Nairobi area (Dagoretti, Wilson, Kabete, MAB), Southeastern Kenya (Machakos, Makindu, Voi, Taita, Taveta, Galole) and Sothern Coastal Strip (Mombasa, Kwale, Mtwapa) are likely to receive near-average to below-average (generally depressed) rainfall. The Northwestern regions (Lodwar, Lokichoggio, Lokitaung), Northeastern Kenya (Marsabit, Moyale, Mandera, Wajir, Garissa, Isiolo) and most of the Coastal strip (Kilifi, Malindi, Msabaha, Lamu) are likely to receive below-average (highly depressed) rainfall. 7. EXPECTED CESSATION Rainfall over most parts of western Kenya, central Rift Valley and parts of South-eastern Kenya is likely to cease during the third to fourth week of December The Central highlands including Nairobi and Southeastern Kenya are likely to experience the cessation during the second to third week of December The Coastal strip is likely to experience the cessation during the first to second week of December The entire Northwestern and Northeastern regions will experience the cessation during the first week of December Indeed, most of these regions are likely to remain generally sunny and dry throughout the month (see figure 4). 8. POTENTIAL IMPACTS Poor crop performance will be expected in most agricultural areas of the country. This is due to the poor rainfall performance expected in these areas. Foliage and pasture conditions in the pastoral areas of Northern, Northwestern and Northeastern Kenya are expected to slightly diminish due to the expected sunny and dry conditions in December. Water levels in both the Seven Folks and Turkwel hydroelectric power generating dams are likely to reduce slightly due to the forecasted slightly depressed rainfall in the catchment areas. The forecasted sunny and dry conditions in areas like Garissa and other regions in Arid and Semi-Arid Lands (ASALs) is likely to lead to a continued drought situation. The current contingency measures should therefore be enhanced to avert any loss of lives due to lack of food and water especially as we move to the January-February 2018 period that is expected to be sunny and dry with very high daytime temperatures. N.B: This forecast should be used in conjunction with the daily 24-hour and the weekly forecasts issued by this Department. MR. PETER G. AMBENJE DIRECTOR OF METEOROLOGICAL SERVICES & PERMANENT REPRESENTATIVE OF KENYA WITH WMO 3

4 Figure 1b: % November 2017 Rainfall Distribution Figure 2b: % OND 2017 Rainfall Distribution 4

5 Figure 3: Rainfall outlook for December 2017 Figure 4: Expected Cessation of OND