Status and Plans for Operational Tropical Cyclone Forecasting and Warning Systems in the North Indian Ocean Region - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 157

probability is estimated directly from the 20-member global ensemble. At each
grid point, the number of ensemble members having a 24-hour precipitation
amount within a specified range (e.g. 1-2 cm, 2-5 cm etc.) is counted (M) and
the probability is expressed as 100 × (M/20).
A cyclone genesis parameter, termed the genesis potential parameter (GPP),
for the North Indian Ocean is developed (Kotal et al., 2009; Kotal and
Bhattacharya, 2013). The parameter is defined as the product of four variables,
namely vorticity at 850 hPa, middle tropospheric relative humidity, middle
tropospheric instability, and the inverse of vertical wind shear. The parameter
is operationally used for distinction between non-developing and developing
systems at their early development stages. The composite GPP value is found
to be around three to five times greater for developing systems than for non-
developing systems. The analysis of the parameter at early development stage
of a cyclonic storm found to provide a useful predictive signal for intensification
of the system. The grid point analysis and forecast of the genesis parameter up
to seven days is also generated on real time (available at http://www.imd.gov.in/
section/nhac/dynamic/Analysis.htm).
A statistical-dynamical model (SCIP) (Kotal et al., 2008) has been
implemented for real time forecasting of 12 hourly intensity up to 72 hours.
The model parameters are derived based on model analysis fields of past
cyclones. The parameters selected as predictors are: Initial storm intensity,
Intensity changes during past 12 hours, Storm motion speed, Initial storm
latitude position, Vertical wind shear averaged along the storm track, Vorticity
at 850 hPa, Divergence at 200 hPa and Sea Surface Temperature (SST). For
the real-time forecasting, model parameters are derived based on the forecast
fields of ECMWF model. The method is found to provide useful guidance for
the operational cyclone forecasting.
4.3 Decision Making Process
To ensure the availability of the data and forecast products from various national
and international sources, an institutional mechanism was developed in
consultation with all the stake-holders. A standard operation procedure (SOP)
has been prepared for monitoring and prediction of cyclonic disturbances and
issue of warning. It includes the road map and check lists for this purpose. All
the above initiatives have resulted in improved cyclone warning service delivery,
timeliness of the warning, and reduction in loss of lives as the outcome.
5. Early Warning System—Organizational Structure
The Cyclone Forecasting Organization in IMD has a three-tier structure
(Fig. 6) to cater to the needs of the maritime states and other users. The complete
Cyclone Warning Programme in the country is supervised by the Cyclone
Warning Division (CWD) at New Delhi. The national and international