REPUBLIC OF KENYA
Ref.
No.
Met/
1622
Date 3 April 2007
MINISTRY OF TRANSPORT
KENYA METEOROLOGICAL DEPARTMENT
Dagoretti Corner, Ngong Road, P. O. Box 30259, Nairobi, Kenya,
Telephone:254-20-3867880-7 / 3876957 / 3873682; Fax:254-20-3876955/3877373
E-mail:director@meteo.go.ke
SEASONAL WEATHER UPDATE
WEATHER REVIEW DURING MARCH AND THE OUTLOOK FOR APRIL 2007
1.
SUMMARY
In March 2007, most parts of the country experienced highly depressed rainfall that was characterised by
poor spatial and temporal distribution. The most depressed rainfall was recorded at Lamu and Msabaha
stations along the coastal strip. The two stations recorded just 0.8 and 5.5mm of rainfall during the entire
month. However, some parts of Western Kenya (Kisumu, Kitale and Kakamega), Central highlands (Meru)
and Southeastern lowlands (Makindu) experienced rainfall that was within their Long-Term Means
(LTM) rainfall for the month but still below 100 percent. Much of the rainfall over these areas occurred in
the first half of the month.
April is the peak month for the “Long Rains” (March-May) season over most parts of the country. The
outlook for April 2007 indicates that most parts of the country including the Western highlands (Kericho,
Kisumu, Kakamega, Eldoret, Kisii), Central Rift Valley (Nakuru, Narok), Central Highlands and Nairobi
(Embu, Nyeri, Meru, Murang’a, Dagoretti), Southeastern districts (Machakos, Makindu, Voi),
Northwestern (Lodwar, Lokichoggio, Lokitaung) and Northeastern Kenya (Mandera, Moyale, Marsabit,
Wajir) are likely to experience generally depressed rainfall. A few areas along the Coastal Strip and
especially the South coast (Mombasa, Mtwapa, Malindi) are however likely to experience slightly enhanced
rainfall.
2.
REVIEW OF THE WEATHER AND PREVAILING SYNOPTIC CONDITIONS DURING MARCH
2007
2.1 REVIEW OF WEATHER DURING MARCH 2007
The analysis of rainfall performance during March 2007 indicates that most parts of the country
experienced highly depressed rainfall. Apart from stations in Western Kenya, most of the other
stations in the country recorded less than 75 percent of their Long-Term Mean (LTM) rainfall. The
areas which experienced the most depressed rainfall included Lamu and Msabaha along the
coastal strip, Machakos in Southeastern Kenya and Thika in the Central highlands of Kenya. The
meteorological stations in these areas recorded rainfall that was less than 20 percent of their
March LTMs. Lamu station for example recorded just 0.8mm of rainfall during the entire month
while Msabaha station recorded just 5.5mm.
Some parts of Western and Central highlands recorded significant amounts of rainfall though not
exceeding 100 percent of their LTMs. The rainfall was however poorly distributed in time and
space. Kisumu station recorded the highest monthly rainfall total of 154.3mm (93%) out of which
62.6mm was recorded in a single day. Kisii, Kakamega, Meru, Kericho, Kitale, Embu, Narok,
Eldoret Airport and Makindu stations recorded 141.5 (71%), 137.3 (80%), 111.1 (96%), 89.4
(51%), 75.2 (81%), 73.7 (62%), 53.2 (53%), 52.1 (52%) and 50.9mm (83%) respectively. The
rest of the stations recorded less than 50mm. See figure1 below.
2.2 PREVAILING SYNOPTIC CONDITIONS IN MARCH 2007
During March 2007 anomalously warm sea surface temperatures (SST) were observed over the
Southwest Indian Ocean near the Mascarene Islands (Re Union, Mauritius) and Mozambique
Channel areas. This led to weaker than average Sub-Tropical High Pressure Systems
(Anticyclone) over the Atlantic and Indian Oceans. Consequently, the Eastern Africa high-pressure
ridge was therefore weak and resulted into a diffuse rain-bearing system commonly referred to as
the Inter-Tropical Convergence Zone (ITCZ). The warm conditions were also conducive for the
formation of Tropical cyclones that hindered moisture influx from the Indian Ocean into the
country. This situation led to the delayed onset and poor rainfall performance over most parts of
the country.
3.
IMPACTS
The delayed onset and also the poor rainfall performance over various parts of the country
impacted negatively to the farming communities especially in the agricultural areas of Western and
Central Kenya. This was more so to the farmers who planted early awaiting the onset of the
seasonal rains. Farmers in some parts of Central Kenya that are yet to receive any rainfall have
not planted, a situation that is already alarming. There is already some indication of stress in terms
of pastures in some pastoral areas like Wajir and Mandera in the Northeastern areas that
previously suffered from serious flooding during the October-December 2006 “short-rains” season.
4.
APRIL 2007 FORECAST
The rainfall forecast for April 2007 is based on regression of prevailing Sea Surface Temperatures
(SSTs) on Kenyan rainfall, Sea Surface Temperature (SST) gradients and the expected evolution
of global SST patterns. The continuing Tropical Cyclone activities in the southwest Indian Ocean
have also been considered. The forecast indicates that most parts of the country are likely to
experience depressed rainfall save for some few areas along South Coast that are likely to receive
slightly enhanced rainfall during the month. The normal (mean) April rainfall distribution is shown in
figure 2. The specific outlooks for individual areas are as follows:
a. The following areas (shown in green in figure 3 below) are likely to experience mainly near
normal rainfall with a slight tendency to above normal (slightly enhanced) rainfall:
i. The southern Coastal Strip (Mombasa, Malindi, Kilifi, Mtwapa)
b. The following areas (shown in yellow in figure 3 below) are expected to receive near-normal
rainfall tending to below normal:
i.
Parts of Eastern Province mainly bordering Central Province (Embu, Meru,
Machakos etc)
ii.
Central Province (Nyandarua, Nyeri, Thika, Murang’a, Kirinyaga);
iii.
Nairobi Province (Kabete, Wilson Airport, Dagoretti, Moi AirBase etc);
iv.
Central and southern parts of Rift Valley Province (Kericho, Kitale, Eldoret, Narok,
Naivasha, Nakuru, etc);
v.
Nyanza Province (Kisii, Kisumu, Nyamira, etc);
vi.
Western Province (Busia, Butere, Mumias, Vihiga, Kakamega, Bungoma); and
vii.
Northern parts of the Coastal Strip (Lamu).
c. The following areas (shown in red in figure 3 below) are likely to receive below normal (highly
depressed) rainfall:
i. The Northwestern regions (Lodwar, Lokichoggio, Lokitaung);
ii. Northeastern Kenya (Garissa, Marsabit, Wajir, Mandera, Moyale, Garbatulla); and
iii. Southeastern Kenya (Machakos, Makindu, Voi)
2
5.



NB:
POTENTIAL IMPACTS
Poor crop performance is expected in most parts of the country due to the expected poor
rainfall performance during this peak rainfall month of April. The agro-pastoral and pastoral
areas in particular are likely to experience water stress in the near future.
Chances of floods occurring in the flood-prone areas of Nyando, Bundalangi and Kano
plains are very low. However, contingency measures should still be put in place in case of
such occurrence especially in cases of short-lived intense rainfall events.
The seven-folks power generating dams are expected to experience below normal inflows
due to the expected depressed rainfall in the catchment areas. The energy sector should
therefore, optimize on hydroelectric power generation and distribution.
This forecast should be used in conjunction with regular updates issued by this
Department.
Sector-Specific forecasts can be provided on request
Dr. Joseph R. Mukabana
DIRECTOR OF METEOROLOGICAL SERVICES
FIGURE 1: RAINFALL PERFORMANCE IN MARCH 2007
3
LOKO
M91
5N
4N
TODEN
62 ILERE
T58
LOKIC
H83
MAND
92
MOYA
185
270MM
LODW
49
3N
ELWA
K90
260
250
MARS
238
2N
BARA
99
ELGO
MARL
162
KITAL
85
N 178
E
COLCH
ELDORE
GARB
98
137
112
ISIOL
T
KAKA
127
259
NANY MERU
244
145
KISUM
214
KAIS NAKUR
125
NYEREMBU KATZE
251
U
170 286
OLEN
158
MONI 206
KISII
NAIV
G
257191
111
THIKA
NARO
211
150
DAGO
219
KATUMAN
I 140
MUTO
120
1N
0
1S
2S
230
WAJIR
92
210
190
170
150
130
GARI
83
110
100
GALO
69
90
80
LAMU
140
MAKI
104
75
70
3S
MALI
171
VOI
89
50 MM
MOMB
168
4S
VANG
132
A
5S
34E
35E
36E
37E
38E
39E
40E
41E
42E
FIGURE 2: MEAN APRIL RAINFALL DISTRIBUTION IN
KENYA
FIGURE 3: RAINFALL OUTLOOK FOR APRIL 2007
4