1. The document analyzes weather data from satellites, models and observations to forecast heavy rainfall and flooding in northwest Kenya around April 10-12, 2013. 2. Analysis of satellite imagery, moisture levels, wind patterns and the position of the Intertropical Convergence Zone predicted strengthening low-level convergence and deep convection leading to widespread heavy showers and thunderstorms. 3. The forecasts unfortunately verified with satellite imagery showing extreme rainfall of 30 mm/hr that caused flooding, destroyed bridges, killed livestock and 3 people in northwest Kenya on April 12th.

1. Kagenyi J.N.
kagenyijn@gmail.com
IMTR-NAIROBI
Kenya

2. Review Weather Events
1. The Following is a step by step a analysis on the
prevailing weather events leading to the flooding
that killed people and destroyed bridges
2. Use of Satellite and Model data as well as synoptic
station observtations from Synergie
3. News paper report on 13th April 20113
2

3. Synergie SAT-Data 10/04/2013
 To Review Past WX from RGB imagery over border of
Kenya and Ethiopia from 0915 to 1800
1. How active is ITCZ ?
2. How is MPE data ( source MPEF )
3. Does MPE pattern follow the ITCZ zones?
4. 24-Hours Night Micro Physics RGB 0915 (for high
deep clouds at night they appear dirty red)
5. Day MicroPhysics RGB149 (Red areas for deep
convection)
6. Note Severe storm RGB12,12,9 violent updrafts at KE-
ET border
3

4. Example : Day Microphysics RGB149
4
1. Look for Deep
convection
areas
2. Animate to
monitor
translation of
development

5. 5
Overlay
MSLP on VIS
at 12 on
11/04/2013.
Area with
likely
convergence
is outlined
NB:
MSLP is a
forecast of
the coming
pressure
field

6. 6
Overlay of
MSLP and
WV7.3 for
MOISTURE
Availability at
lower levels of
atmosphere.
Identify Areas
of great impact
by both north
PG and
southern PG
** Deep
convection is
possible

7. 850 hPa Confluence zones by streamlines on Color
composite At 4:000 11/04/2013
7

8. 700 hPa streamlines: 12/04/2013
8
Depth of
Convergence

9. 850 hPa streamlines: 11/04/2013
12utc
9

10. 00 streamlines at
850 hPa on 11/04.
color composite
imagery 0400
morning.
>High moisture is
evident
> Convergence in
the area
10

11. @NWP data
 Analyze MSLP surface pressure: determine position
and Intensity of EA Ridge, Arabian Ridge, Intensity
and Orientation of Libyan Ridge. Position of ITCZ
 Is the region under low pressure? 12 UTC 11/4/13
 Fcast 24 hrs 11th /04/13 Convergence Intensification
(pressure build up in south & Northern Areas)
 Fcast 48 hrs 12th/04/13 Convergence Intensification
 View Animation MSLP and Winds, Streamlines
Mentor model 12th weather is likely to be dangerous
11

12. 10/04/13 Fcast 00-12utc
12
Active ITCZ
surface
Position on
MSLP 10/04/13
at 12:00

13. Expected streamlines 850 hPa: 12/04/2013
13
24 hrs fcast
Streamlines
observation
Strong
Convergence
at 850 on
12/4/2013

14. Expected Wind field at 850 hPa: 12/04/2013
14
Deep
confluence
up to 850
hPa
Vertical
lifting
certain

15. Low
pressure belt
identified as
area of low
level
convergence
(ITCZ)
Expected pressure field: 12/04/2013
15

16. 24 hr Pressure Fcast valid 12 utc 12/04
16

17. Most Fcast 48HR
from 10/04/13
active zone.
You start
agreeing with
NWP fcast when
Sat data
coincides with
fcast
17

18. Streamlines
confluences
along deep
clouds. ITCZ
Position?
18

19. Synoptic data 18:00 10/04/13
 Review the observed reported data from regional
synoptic stations
 NW Kenya (Lodwar reports Ta-Td = 2 degrees Humid
and warm (Ta=23 Td =21)
 Usually Depression for Lodwar, semi-arid area is
usually greater than 5: low relative humidity.
19

20. Observed Synoptic: 10/04/2013 18:00
20
A station to the
East of Lodwar,
Wajir reported
few CBs with Clod
base 2400 ft

21. Synoptic at 19:00 0n 10/4/13
 Broken
Clouds at
2200 ft
21

22. Expected
pressure
patterns on
12/4/13 at 12
utc
22

23. 24 hrs Fcast
low level
convergence
from surface
to 850 hPa
23

24. Overlay of
WV6.2
with MSLP
11/4/2013
at 12:00
ITCZ is Very
Active’
Moisture is
sufficient
Wind field
confluent
24

25. MPE at 04:45 LODWAR ONLY TRACE
25
At 04:00
Dated: 12/4/2013

26. MPE at 5:30 25 mm/hr
26
Dated: 12/4/2013

27. MPE at 6:00 28mm/hr
27
Dated: 12/4/2013

28. observation: 11-12/04/2013
28
•NW Kenya in Lodwar
to the west of Lake
Turkana.
•At 01;15 No active WX
but 6 hours later heavy
storm and flooding
occurred
•Facts: Area with deep
moisture for
convection,
•Strong pressure
gradient,
•Active ITCZ across
•Cloud top Temp: -75-
81 o C

29. 11th 04-2013- From Analysis:
 Animations On 11 from 00-06-12-18-00 compare RGB
NMP, for 0615-1230, indicates enhanced WV,
 WV6.2 HUMIDITY PLENTY
 MSLP SUGGEST INTENSE ITCZ
 WIND FIELD CONVERGENCE
 RUN 12 UTC SHOWS CONVERGENCE ON 12TH AT 12
UTC
 MOISTURE >80, Instability on GII >43K
 EA RIDGE PRESSURE GRADIENT INTENSIFYING
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30. What happened as shown on WV
30

31. FORECAST FOR 12/04/2013
a) Deep convection is expected leading to Heavy
Showers and Thunderstorms at wide spread level in
NW Kenya
b) Landslides on sloppy areas, Flooding on low lands
are most likely to occur
c) Evacuations alert should be dispatched to
administration and safety agencies.
d) Human and animals not allowed to be in the valleys
31

32. Enhanced WV6.2 temp -81 , -24
32

33. VERIFICATION: What happened?
1. USING SATELLITE IMAGERY
2. REPORTS FROM MEDIA
 Water vapour 6.2 microns (Enhanced on
temperatures) Displays the heavy storms that
generated 30 mm/hr that flooded the area on NW
parts of Kenya
 Bridges were run over, flooding animals were killed
including loss of life (3 persons).
33