21 st May 2012 Case Study for Gode zone (Somali region) flood due to heavy rainfall

1. National Meteorological Agency of Ethiopia 21st May 2012 Case Study for Gode zone (Somali region) flood due to heavy rainfall Gode Chali Debele (Senior Meteorologist) Meheret Muluneh (Senior Forecaster)

2. Contents 1. Event2. Forecast3. Verification4. Discussion5. Conclusion

3. 1. Event • On 21st May 2012, a severe weather event occurred in the South-eastern part of Ethiopia at place of Gode. • The event was in the form of heavy precipitation. the rainfall amount of measurement was 50.1 mm. • The flash flooding result in loss of house, property and crop yield . • More than 702 households were affected by flash flooding on 21 May 2012 in Gode zone (Somali region). The flooding caused significant damage, with numerous livestock deaths and damage to planted crops and stored food reported in the affected areas.

4. 2. RSMC-Nairobi Guidance Forecast

5. RSMC-Nairobi Guidance Forecast Day1 for 21st May 2012 Ethiopia Region

6. SWFDP GUIDANCE PRODUCTS SHORT-RANGE (DAY 1 AND DAY 2) Issue Date: Monday 20th May, 2012 Valid for 20th and 21st May, 2012 Regional and global models were employed in this forecast Day 2: Monday 21st May, 2012 Heavy rains expected over western and Central Kenya, Ethiopia, Northern Tanzania and southern Uganda. Winds with more than 25 knots expected over Kenya and Tanzania. Wave height with more than 2 meters expected over the coastal regions as indicated on the risk table. Degree of confidence: High.

7. MEDIUM-RANGE (DAY 3 TO DAY 5)Issue Date: Saturday 19th May, 2012

8. Forecast -RSMC-Kenya • RSMC-Nairobi Guidance Forecast Day4 for 21st May 2012

9. 3.Verification In each case, the extreme weather is identified by comparing the actual and the model forecast product.

10. 3.1 Actual amount of rainfall on 21st May 2012 over Ethiopia On 21st May 2012 heavy rainfall of 50.1mm was reported at Gode station Gode

11. 3.2 Satellite Imagery on 21st May 2012 The satellite picture indicates dense patches of cloud over the southeastern Ethiopia (affected areas)

12. 3.3 Verification of day 1(Mon 21st )guidance forecast issued against the actual observed on 21st May 2012. • Relationship between the model forecast and local observed weather. The RSMC guidance forecast indicate heavy rainfall across eastern and southern Ethiopia which is false alarm and also missed heavy fall at places of Gode station CV Gode

13. 4. Discussion • RSMC-Nairobi Guidance Forecast Day1-4 for 21st May 2012 missed heavy fall over south-eastern part of Ethiopia. but false alarm was provided by the RSMC-Nairobi Guidance. • while satellite picture has the corresponding signal of the event. • In general, the model (RSMC), which were analyzed, did not suggest heavy precipitation over the south-eastern part of Ethiopia.

14. 5. Conclusion • RSMC-Nairobi Guidance model not captured the event across southeastern parts of the country. • There is a need to perform further validation studies over different topography of Ethiopia. • The heavy rainfall forecasting model needs to be adjustment accordingly for better use in sever weather monitoring activities in Ethiopia.