India Meteorological Department Tropical Cyclone Advisory #12 DEPRESSION BOB05-2013 8:30 AM IST November 15 2013 ==================================== At 3:00 AM UTC, the depression over southwest Bay of Bengal moved southwestward and lays center near 9.5N 83.5E, about 530 km southeast of Chennai, and 420 km east southeast of Nagapattinam. The system would move west northwestward and cross northern Tamil Nadu coast near Nagapattinam some time around Saturday evening. According to satellite imagery, the Dvorak intensity of the system is T1.5. Associated broken low/medium clouds embedded with intense to very intense convection is seen over Bay of Bengal between 8.0N to 12.5N and 80.0E to 85.0E. The lowest cloud top temperature due to convection is about -80C. 3 minute sustained winds near the center is 25 knot with gusts of 35 knots. The state of the sea is rough to very rough around the center. The central pressure of the depression is 1003 hPa. Oceansat-II observations based on 1830 UTC November 14 indicate 20-30 knots in northwest and northeast sector and 15-25 knots in southern sector. The upper tropospheric ridge runs along 14.0N in association with the anticyclonic circulation to the northeast of the system center. The low level convergence along with low level relative vorticity remained same during past 12 hrs. The sea surface temperature is about 28-29c and ocean thermal energy is about 60-80 kj/cm2. The vertical wind shear of horizontal wind is moderate to high (15-25 knots). Due to this high wind shear, the convection shows flaring and ragged wrapping. The Madden-Jullian Oscillation index lies over phase 3 with amplitude less than 1. Numerical weather prediction models suggest that Madden-Jullian Oscillation would move to phase 2 during next 24 hrs with decreasing amplitude. It is not supportive for intensification. Numerical weather prediction models guidance continues to show large variations with respect to track, landfall point and landfall time though most of the models suggest the landfall over Tamil Nadu. With respect to intensification, there is more consensus suggesting no further intensification. Even some models suggest weakening of the system before landfall. Current forecast is based on consensus Numerical weather prediction and dynamical statistical guidance and synoptic analysis.
Posted on: Fri, 15 Nov 2013 13:36:19 +0000
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