Abstract:
Heavy rainfall has potential damage to the life and properties of the people of
Bangladesh. But forecasting of this weather phenomenon is the most challenging one in
context of both location and time specific. Latest technologies like Doppler radar have
enabled meteorologists to understand the characteristics and it is proven to be helpful in
now-casting. Numerical modeling of this synoptic scale phenomenon was difficult in the
past due to the non-availability of data with fine resolutions. Now-a-days, simulation
facilities of these events have improved a lot due to the development of information
technologies as well as conventional and non-conventional observations that provide
data with high resolution. The simulation using meso-scale models would helpful to
understand the underlying causes of this weather event. Most of the atmospheric
prediction centres using global numerical models at present to predict the atmospheric
variables including heavy rainfall or precipitation and regional models for higher spatial
resolution. But regional models like MM5 are widely used to predict such type of
weather system. Local modeling efforts have expanded dramatically with explosion of
inexpensive, high-speed personal computers. Many National Weather Services (NWS)
run the NCAR /PSU MM5 models using personal computers. In order to run regional or
local models initial and boundary conditions are collected from the National Centers for
Environmental Prediction (NCEP). In this regard it is essential to justify the prediction
capability of MM5 model using existing facilities so that forecasters can use it in their
day to day forecast.
In this study fifth generation non-hydrostatic meso-scale model MM5 was run
individually for five cases separately with the horizontal resolution of about 8.9 km (~
9.0 km) and 2.97 km (~ 3.0 km) with the two selected domains D1 and D2 respectively.
Case 1 (during 0000 UTC of 09 April to 0000UTC of 11 April 2007), Case 2 (during
0000 UTC of 21 April to 0000UTC of 23 April 2007), Case 3 (during 0000 UTC of 07
May to 0000UTC of 09 May of 2007) and Case 4 (during 0000 UTC of 10 June to
0000UTC of 12 June 2007) are run for the period of 48 hours and Case 5 (during 0000
UTC of 15 June to 1800UTC of 17 June 2007) is run for 66 hours with initial conditions
collected from NCEP. The model predictions for these cases were having good
indication about the events with respect to time and location. The amounts of simulated
rainfall were comparable with the rain gauge value and TRMM estimation. The point or
location specific simulated rainfall was comparable in some cases but for other cases the
results were not satisfactory.
