Extended Range Tropical Cyclone Predictions for East Coast of India - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 136

gradient across the cyclone and the magnitude of the cyclone's lower
troposphere and middle to upper troposphere's thermal wind. After the tracking
scheme has been implemented for each ensemble member, any tracks that
originate over land are removed unless the ensemble tracks are within
300 n mi (1 n mi = 1.852 km) of an observed tropical cyclone. Furthermore, all
ensemble forecast tracks must have a lifetime of at least one day. The scheme
does have limitations with respect to exceedances in lower-tropospheric winds
and relative vorticity, which can produce unrealistic track forecasts, such as in
the vicinity of 108-178N, 408-558W.
3. Medium Range Forecasts for Cyclone Genesis
Potential and Tracks in South and Central Bay of
Bengal (2007-2010)
Extended range CFAN cyclone genesis potential and tracks predictions for
low-pressure systems, in South and Central BoB since 2007 are analysed. Here
we are presenting a few extended range prediction results for the tropical
cyclones formed in BoB.
3.1 Cyclone Sidr (12 th -16 th Nov 2007)
An area of disturbed weather developed near the Andaman Islands on November
9. Initially moderate upper-level wind shear inhibited organization, while
strong diffluence aloft aided in developing convection. Vertical shear decreased
greatly as the circulation became better defined, and a Tropical Cyclone
Formation Alert was issued on November 11.
The Joint Typhoon Warning Center (JTWC) named it to TC 06B
after Dvorak estimates indicated winds of 65 km/h. Later that day, it intensified
into a deep depression as it moved slowly northwestward. IMD upgraded the
system to Cyclonic Storm Sidr early on November 12. The system then began
to intensify quickly as it moved slowly northwestward, and the IMD upgraded
it to a severe cyclonic storm later that day and a very severe cyclonic storm
early the next day.
On the morning of November 15, the cyclone intensified to reach peak
winds of 215 km/h according to the IMD, and a peak of 260 km/h according to
the JTWC best track. Sidr officially made landfall around 1700 UTC later that
day, with sustained winds of 215 km/h. On 2 nd November 2007, CFAN predicted
the very high tropical cyclone potential genesis probability near South East
BoB and adjacent to Andaman Sea, which is extended up to Central BoB (Fig.
1, right). CFAN model predicted the Sidr cyclone genesis with lead-time of
eight days. CFAN Ensemble mean trajectory and intensity predictions (Fig. 2,
right) on 11 th Nov indicated that Cyclone Sidr would move northward direction
and landfall near South Bangladesh.