&S
REPUBLIC OF KENYA
MINISTRY OF ENVIRONMENT & NATURAL RESOURCES
KENYA METEOROLOGICAL DEPARTMENT
Dagoretti Corner, Ngong Road, P. O. Box 30259, 00100 GPO, Nairobi, Kenya
Telephone: 254 (0) 20 3867880-7, Fax: 254 (0) 20 3876955/3877373/3867888,
E-mail: [email protected], [email protected] Website: http://www.meteo.go.ke
Ref. No. KMD/FCST/4-2017/MO/05
Date: 29th May 2017
WEATHER REVIEW DURING MAY AND THE FORECAST FOR JUNE 2017
1. HIGHLIGHTS
WEATHER REVIEW FOR MAY 2017
The month of May marks the cessation of the “Long Rains” season over most parts of the country. However, this
is the peak rainfall month for the coastal strip. The western highlands also continue to receive significant
amounts of rainfall into June.
During May 2017, most parts of the country recorded generally depressed rainfall that was also poorly
distributed both in time and space. The Coastal region, however, recorded enhanced rainfall that exceeded 125
percent of the Long-Term Mean (LTM) for May at some stations. Short-lived and very intense rainfall events
significantly contributed to the enhanced rainfall that resulted associated flash floods in some isolated parts of
this region. Mtwapa and Mombasa were respectively pounded by 192.5mm and 235.1mm in 24 hours on 8 th
May 2017 just four days after having recorded 75.2mm and 64.8mm on 4 th May 2017.The 235.1mm at
Mombasa surpassed the 233.3mm that was recorded on 19th October 1997 at the same station during the 1997
El-Nino related heavy rains.
THE FORECAST FOR JUNE 2017
June is generally a dry month over most parts of the country except the western and coastal parts. The weather
outlook for June 2017 indicates that most parts of the country are expected to remain generally dry as
reminiscent of this month. However, the western and coastal areas will continue to receive significant amounts
of rainfall. The June 2017 outlook is as follows:
•The Western areas (Kericho, Kisumu, Kakamega, Kisii, Kitale, Eldoret) and parts of Central Rift Valley
(Nakuru, Nyahururu), are likely to receive near normal rainfall tending to above normal (slightly enhanced
rainfall). This rainfall may occasionally spread eastrwards to Nairobi and central Kenya.
•The Coastal Strip (Mombasa, Mtwapa, Kilifi, Malindi, Msabaha, and Lamu) is likely to receive near normal
rainfall with a tendency to above normal (enhanced rainfall).
•Occasional cool and cloudy conditions are expected to prevail in the central highlands (Meru, Nyeri, Embu
etc) and Nairobi area during the month as the cool season gradually sets in. However, warmer than average
temperatures are expected during the month.
2. REVIEW OF RAINFALL PERFORMANCE DURING MAY 2017
The rainfall analysis for May 2017 indicates that much of the country experienced generally depressed rainfall
during the month. This was more so in Northwestern, Central including Nairobi and parts of Northeastern
Kenya where most meteorological stations recorded below 50 percent of their monthly LTMs. The Coastal
region, however, recorded enhanced rainfall that was characterized by heavy storms. Isolated areas in the
region experienced flash floods that occurred as a result of the heavy storms. For example: Mtwapa and
Mombasa were respectively pounded by 192.5mm and 235.1mm in 24 hours on 8th May 2017 just four days
after a lashing of 75.2mm and 64.8mm on 4th May 2017.The 235.1mm at Mombasa surpassed the 233.3mm
that was recorded on 19th October 1997 at the same station during the 1997 El-Nino related heavy rains. The
monthly rainfall totals over these two stations were 207% and 189% of their LTMs respectively.
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Elsewhere, most stations in western Kenya and some stations in the central highlands recorded near-average
to enhanced rainfall during the month.
Meru station recorded the highest percentage of 227.5%. Lodwar and Wajir did not record any rainfall
throughout the month while Wilson Airport station in Nairobi received a paltry 38.3mm of rainfall that was
just 38 percent of its May LTM. (See Figure 1.)
Up to 28th May, Mtwapa Meteorological Station along the Coastal strip recorded the highest monthly rainfall
total of 586.9mm (189%) as compared to its May LTM of 310.2mm. Other stations that recorded more than
200 mm of rainfall include Mombasa-524.2mm (207%), Msabaha-354mm (114%), Lamu-290mm (95%),
Malindi-255.9mm (82%), Nyeri-255.7mm (114.3%), Meru-241.1mm (227.5%), Kericho-240.4mm (89.8%),
Kakamega-212.3mm (86%) and Embu-210.2 (128.6%). Eldoret A/p, Kisii, Kitale, Eldoret met., Laikipia, Moyale
and Kisumu stations recorded between 100 and 200mm while the rest of the stations recorded less than 100
mm as depicted in Figure 2.
3. SYNOPTIC CONDITIONS IN MAY 2017
During the month of May, Cooler Sea Surface Temperatures (SSTs) prevailed over much of the Indian Ocean
and more so the eastern side. Slightly warmer SSTs were also observed over the eastern parts of the
equatorial Atlantic Ocean. Slightly warm SST anomalies were observed over the eastern and central equatorial
Pacific Ocean (the Niño areas).
The Mascarene region was characterized by weaker than average pressures. Pressures over the Arabian region
were also generally weak for most of the month. The Zonal (east-west) arm of the Inter-Tropical Convergence
Zone (ITCZ) therefore remained very diffuse for most of the period and this led to the poor rainfall
performance over most of the eastern half of the country. The Meridional (North-South) arm of the ITCZ was
mainly over Uganda and some parts of western Kenya.
4. EXPERIENCED IMPACTS
The depressed rainfall recorded over much of the country was associated with:
 Improved crop performance over the agricultural areas of the country including the maize-basket
areas of Kitale, Eldoret etc.;
 Poor pasture for livestock especially in the pastoral areas of Narok, Kajiado and other areas within the
Rift Valley and the northern parts of the country due to delayed onset, poor rainfall performance and
early cessation of the Long Rains season;
 Slight increase in water levels in the Seven-Forks as well as Turkwel and Sondu Miriu hydroelectric
power generation dams;
 Flash floods that destroyed property and infrastructure in the coastal strip due to intense rainfall
 Landslides in parts of central Kenya
5. OUTLOOK FOR JUNE 2017
This forecast is based on regression of sea surface temperatures (SSTs) and SST gradients on rainfall over
western Kenya and the Coastal region. Climatology was applied elsewhere in the country. The forecast
indicates that most parts of the country will be generally dry during the month. However, near-average rainfall
tending to above-average (slightly enhanced rainfall) is expected over most parts of western Kenya while the
Coastal strip of Kenya is likely to experience near-average rainfall tending to above-average (enhanced rainfall)
as seen in figure 4.
Occasional cool and cloudy conditions accompanied with light morning rains/drizzles will be observed in the
central highlands including Nairobi area and some parts of western Kenya and central Rift Valley as the cool
season gradually sets in.
The specific outlook for individual areas is as follows:
The Highlands west of the Rift Valley (Kitale, Kericho, Nandi, Eldoret, Kakamega), Lake Basin (Kisumu, Kisii,
Busia), parts of Central Rift Valley (Nakuru, Nyahururu) are likely to receive near normal rainfall tending to
above normal (slightly enhanced rainfall).
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The Coastal strip (Mombasa, Mtwapa, Malindi, Msabaha, Kilifi, Lamu) is expected to receive near normal
rainfall with a tendency to above normal (enhanced rainfall).
The Highlands East of the Rift Valley (Nyeri, Muranga, Kiambu, Embu, Meru), Nairobi area (Dagoretti,
Wilson, Eastleigh, Kabete etc) are expected to experience occasional cool and cloudy (overcast skies for long
hours of the day) conditions with occasional light morning rains. A few days are expected to be cold and chilly
daytime (maximum) temperatures falling below 20°C in various parts due to overcast skies for long hours.
Northwestern regions (Lodwar, Lokichoggio, Lokitaung), Northeastern Kenya (Marsabit, Garbatulla, Wajir,
Mandera, Moyale) and Southeastern Kenya (Machakos, Makindu, Voi) are likely to remain generally sunny
and dry. Occasional cool and cloudy conditions may occur over some parts of southeastern Kenya especially
those bordering the central districts.
6. POTENTIAL IMPACTS
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The expected near normal to slightly enhanced rainfall in Western Highlands will lead to further
improvement in crop performance in the areas.
Crops in the central highlands are likely to benefit from the occasional cool and cloudy conditions with
light drizzles
The generally dry weather condition expected elsewhere in the country implies that the crops in these
areas will be adversely affected leading to poor harvest.
Food security is expected to deteriorate over most parts of the country and more so the northern
areas of Kenya.
Problems related to water scarcity and lack of pasture for livestock is expected to arise especially in
the Arid and Semi-Arid Lands (ASALs), due to the expected sunny and dry weather conditions in June
2017.
Cases of respiratory diseases like asthma, pneumonia and common colds (flu) are likely to occur in
areas like Nairobi, Central highlands, Central Rift Valley and parts of the highlands west of the Rift
Valley, due to the expected cool/cold conditions.
The water levels in the hydro-electric power generation dams in central Kenya are expected to reduce
start declining during the month of June due to the expected dry weather conditions in the river
catchment areas.
NB: This forecast should be used in conjunction with regular updates issued by this Department.
Mr. Peter G. Ambenje
DIRECTOR OF METEOROLOGICAL SERVICES & PERMANENT REPRESENTATIVE OF KENYA WITH
WMO
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FIGURE 1: PERFORMANCE OF MAY 2017 RAINFALL VS. LONG TERM MEAN
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FIGURE 2: RAINFALL PERFORMANCE IN MAY 2017
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FIGURE 3: RAINFALL PERFORMANCE IN MAM 2017
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FIGURE 4: JUNE 2017 WEATHER OUTLOOK
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