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By Dr. H. Kabelwa
What is WRF?Is the Weather Research and Forecasting
ModelIs 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.
Domain of LVBWRF model is run over East African (bigger
domain) http://www.meteo.go.tz/pd/index.phpwith 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 1:3WRF model is initialized from Global Forecast
System (GFS) data of 1200z.The model is run for 72 hrs starting from 1200z
every day.
Products Accessibility: EAD
Products Accessibility: EAD
Products Accessibility: LVB
WIND FLOW WIND AT 850hPa WIND AT 700hPa
WIND FLOW (cont..WIND AT 500hPa WIND AT 200hPa
RELATIVE HUMIDITYRH AT 850hPa RH AT 700hPa
WRF modelStrengthHigh resolution in space, 5km. High resolution in time, 3hr model outputs. 3-hour accumulated rainfallProducts: Wind profile, wind flow patterns,
Relative humidity, PW , etcMost of the time Captures the Lake features.
Comparison against Observations
24HRS RAINFALL ACCUMULATIONAS PER 07/11/2012 0600z
Satellite imagery of IR&VIS 07/11/2012 at 1015z
KIGOMA 10.6
KIBONDO 5.1
MWANZA 1.8UKIRIGURU 6.4
MUSOMA TRBUKOBA NIL
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
WRF modelWeaknessForecasting length - 48hrsVery sensitive to atmospheric conditions.No data assimilationWind gust cannot well capture
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.
A way forwardMore research is required on physics and
paramaterization settings on the