South Indian: 21S(GUAMBE) forecast to intensify to 80knots( Strong Category 1) by 48hours, 17/21utc update

21S(GUAMBE). ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH A DEVELOPING CENTRAL DENSE OVERCAST FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC).

21S( GUAMBE). WARNING 1 ISSUED AT 17/21UTC. UPPER-LEVEL ANALYSIS INDICATES MARGINALLY-FAVORABLE CONDITIONS WITH LOW TO MODERATE VERTICAL WIND SHEAR OFFSET BY NEAR RADIAL OUTFLOW AND WARM (29-30C) SST VALUES.THERE IS SOME UNCERTAINTY IN THE INITIAL POSITION DUE TO THE PRESENCE OF DEEP CONVECTION OVER THE LOW LEVEL CENTER AND THE LACK OF HIGH-RESOLUTION MICROWAVE IMAGERY AT THIS TIME. TC 21S IS FORECAST TO TRACK SOUTHWARD TO SOUTH- SOUTHWESTWARD THROUGH 72H ALONG THE WESTERN PERIPHERY OF A NORTH- SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. AFTER 72H, THE SYSTEM WILL RECURVE SOUTHEASTWARD TO EAST-SOUTHEASTWARD AS IT ROUNDS THE STR AND BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES. EXTRA-TROPICAL TRANSITION WILL COMMENCE NEAR 96H AND CONTINUE AT 120H AS THE SYSTEM TRACKS WITHIN THE WESTERLY FLOW ALONG THE NORTHERN EDGE OF THE BAROCLINIC ZONE.TC 21S IS EXPECTED TO GRADUALLY INTENSIFY THROUGH 48H WITH A PEAK INTENSITY OF 80 KNOTS/CATEGORY 1 AT 48H. STEADY WEAKENING WILL OCCUR AFTER 72H AS VERTICAL SHEAR INCREASES AND SST VALUES COOL TO 26-27C.

21S(GUAMBE). 17/1838UTC. ASCAT-B IMAGE SHOWING A SWATH OF 40-45 KNOT WINDS OVER THE EASTERN SEMICIRCLE. ADDITIONALLY, A 171827Z SCATSAT IMAGE SHOWED 43-47 KNOTS OVER THE EASTERN QUADRANT.

21S(GUAMBE). NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT AND SUPPORTS THE JTWC FORECAST TRACK WITH MODERATE CONFIDENCE.

21S(GUAMBE). 17/1535UTC. SMAP READ WINDS OF 53KNOTS( 10MINUTES AVERAGE) WHICH IS SIGNIFICANTLY ABOVE THE 1MINUTE ESTIMATE FROM JTWC AT 17/18UTC.

21S(GUAMBE). 17/2215UTC. Eumetsat. Enhanced by Patrick Hoareau.

17/2130UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON 01W AND 12HOURLY WARNINGS ON 21S. 3 HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.