Current Southern Hemisphere Tropical Systems: Tropical Cyclone 15S (Gino)

120300Z POSITION NEAR 14.8S 80.5E.
TROPICAL CYCLONE (TC) 15S (GINO), LOCATED 650 NM SOUTHEAST OF DIEGO
GARCIA, HAS TRACKED SOUTH-SOUTHWESTWARD AT 06 KNOTS OVER THE PAST SIX
HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE CENTRAL
CONVECTION HAS EXPANDED AND DEEPENED WHILE MAINTAINING RELATIVE
SYMMETRY. THE INITIAL POSITION, BASED ON THE ABOVE ANIMATION AND
EXTRAPOLATED FROM A 112059Z AMSU-B MICROWAVE IMAGE, IS PLACED WITH
POOR CONFIDENCE DUE TO THE LOW LEVEL CIRCULATION BEING OBSCURED BY
THE CENTRAL CONVECTION. THE INITIAL INTENSITY IS BASED ON CONGRUENT
DVORAK ESTIMATES FROM PGTW AND KNES. UPPER LEVEL ANALYSIS INDICATES
THE SYSTEM IS UNDER A RIDGE AXIS IN AN AREA OF LIGHT (05-10 KNOT)
VERTICAL WIND SHEAR (VWS) AND EXCELLENT RADIAL OUTFLOW. THE CYCLONE
IS TRACKING ALONG THE NORTHWEST PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE, WHICH IS FORECAST TO WEAKEN WITH THE APPROACH OF A
MID-LATITUDE SHORTWAVE TROUGH OVER THE NEXT 48 HOURS, ALLOWING THE
SYSTEM TO RE-CURVE INTO THE MID-LATITUDE WESTERLIES. TC 15S IS
FORECAST TO INTENSIFY THROUGH TAU 48 UNDER FAVORABLE UPPER-LEVEL
CONDITIONS, PEAKING AT 85 KNOTS. AFTER TAU 48, THE SYSTEM WILL BEGIN
TO WEAKEN DUE TO INCREASING VWS AND COOLER SST (LESS THAN 25C). TC
GINO IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 72
AND WILL COMPLETE ETT BY TAU 96 AS IT BECOMES EMBEDDED WITHIN THE 
BAROCLINIC ZONE. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT WITH
MINOR DIFFERENCES IN THE TIMING OF RE-CURVATURE AND TRACK SPEEDS IN
THE EXTENDED TAUS. THERE IS HIGH CONFIDENCE IN THE JTWC TRACK
FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 120000Z IS 20 FEET.

- JTWC + Eumetsat