1. By Dr. H. Kabelwa

2. What is WRF? Is the Weather Research and Forecasting Model Is a next-generation meso-scale numerical weather prediction system Is designed to serve both operational forecasting and atmospheric research needs. It features multiple dynamical cores, Data assimilation system.

3. Domain of LVB WRF model is run over East African (bigger domain) http://www.meteo.go.tz/pd/index.php with nested over Lake Victoria (small domain) http://196.46.109.62/NEST/ The resolution of big domain is 15km while that of small domain is 5km with ratio of 1:3 WRF model is initialized from Global Forecast System (GFS) data of 1200z. The model is run for 72 hrs starting from 1200z every day.

4. Products Accessibility: EAD

6. Products Accessibility: LVB

7. WIND FLOW WIND AT 850hPa WIND AT 700hPa

8. WIND FLOW (cont.. WIND AT 500hPa WIND AT 200hPa

9. RELATIVE HUMIDITY RH AT 850hPa RH AT 700hPa

10. WRF model Strength High resolution in space, 5km. High resolution in time, 3hr model outputs. 3-hour accumulated rainfall Products: Wind profile, wind flow patterns, Relative humidity, PW, etc Most of the time Captures the Lake features.

11. Comparison against Observations 24HRS RAINFALL ACCUMULATION AS PER 07/11/2012 0600z Satellite imagery of IR&VIS 07/11/2012 at 1015z KIGOMA 10.6 KIBONDO 5.1 MWANZA 1.8 UKIRIGURU 6.4 MUSOMA TR BUKOBA NIL

12. Observations Both 850 and 700hPa wind flow patterns show convergence of North-easterly and Easterly winds over southern part of LVB At 500hPa shows northward movement of convergence line The moisture flux also shows some good agreement with areas of convergence Precipitation forecast also give good signal which tiles with rainfall observation and satellite imagery

13. WRF model Weakness Forecasting length - 48hrs Very sensitive to atmospheric conditions. No data assimilation Wind gust cannot well capture

14. Event  Location of the event is the western part of the lake Victoria in the Tanzanian side.  Strong winds occurred in some of the villages in Rural Bukoba district. 30 knots was reported AT Bukoba station which is located a couple of tens of kilometers away. Note: RFSC-Dar threshold for strong/severe wind is 20 knots.  Basing on the evidence of damage caused and reports from the villagers the case is suspected to be of a tornado.  Heavy precipitation did not Happen with only 10.1 mm Recorded at Bukoba station.

15. A way forward More research is required on physics and paramaterization settings on the