Tropical Storm Activity: South Indian Ocean (15 January 2013)

Update: Tropical Cyclone 09S (Emang) Issued at 14/2100Z

142100Z POSITION NEAR 13.2S 78.6E.
TROPICAL CYCLONE (TC) 09S (EMANG), LOCATED APPROXIMATELY 515 NM
SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHWESTWARD AT 06 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE BANDING EVEN AS
THE LOW LEVEL CIRCULATION CENTER HAS MOVED UNDER THE CENTRAL
CONVECTION. THE INITIAL INTENSITY IS BASED ON CONGRUENT DVORAK
ESTIMATES FROM PGTW, KNES, AND FMEE. THE INITIAL POSITION IS BASED ON
THE ABOVE ANIMATION WITH POOR CONFIDENCE. UPPER LEVEL ANALYSIS
INDICATES THE SYSTEM IS 07 DEGREES NORTH OF THE RIDGE AXIS IN AN AREA
OF LIGHT TO MODERATE 10-20 KNOT VERTICAL WIND SHEAR (VWS). THE
CYCLONE IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE TO THE SOUTH. THIS RIDGE IS EXPECTED TO BUILD OVER
THE NEXT 12-24 HOURS CAUSING TC 08S TO TRACK ON A MORE WESTWARD
TRAJECTORY. AS THE SYSTEM GETS CLOSER THE THE RIDGE AXIS, THE VWS
WILL WEAKEN AND PROMOTE GRADUAL INTENSIFICATION. THE LIMITED
AVAILABLE NUMERICAL GUIDANCE IS IN TIGHT AGREEMENT. GIVEN THE SOLID
STEERING PATTERN AND THE TIGHT GROUPING IN THE NUMERIC GUIDANCE,
THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 141800Z IS 15 FEET.

- JTWC + Eumetsat