SOUTH INDIAN: 26S(SEROJA) forecast to intensify significantly after 48h/ 27S: slow-moving, 06/03utc update

06/04/2021

06/02UTC. 7H LOOP. TC 26S(SEROJA) ON THE RIGHT AND TC 27S. IF NEEDED CLICL TO ANIMATE.

2021 APR 06 03UTC #SOUTHERNHEMISPHERE #SOUTHINDIANOCEAN
TC #26S #SEROJA  #WESTERNAUSTRALIA
WARNING 7
As of 00:00 UTC Apr 06, 2021:
Location: 11.5°S 120.1°E
Maximum Winds: 55 kt ( 100km/h)
Gusts: 70 kt ( 130km/h)
Minimum Central Pressure: 991 mb
INTENSIFYING
26S(SEROJA) LOCATED AT 06/00UTC APPROXIMATELY 1360 KM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 13 KM/H OVER THE PAST SIX HOURS.
Satellite bulletins are to be found in the comments of this post on JTWC BIS
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TC 27S  #SOUTHINDIANOCEAN #WESTERNAUSTRALIA
WARNING 5
As of 00:00 UTC Apr 06, 2021:
Location: 16.3°S 105.4°E
Maximum Winds: 40 kt ( 75km/h)
Gusts: 50 kt ( 95km/h)
Minimum Central Pressure: 999 mb
27S LOCATED AT 06/00UTC APPROXIMATELY 1130 KM NORTHWEST OF LEARMONTH, AUSTRALIA, HAS
TRACKED SOUTHEASTWARD AT 05 KM/H OVER THE PAST SIX HOURS.
Satellite bulletins are to be found in the comments of this post on JTWC BIS

Cheers,
Patrick Hoareau
M974World
ILES SOEURS
Cyclone Class 4
 Cheers,PH.

Joint Typhoon Warning Center

26S(SEROJA). WARNING 7 ISSUED AT 06/03UTC.UPPER-LEVEL ANALYSIS REVEALS A MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE (15-20 KNOTS) VERTICAL WIND SHEAR OFFSET BY DIFFLUENT FLOW ALOFT. TC 26S IS FORECAST TO TRACK ALONG THE NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE POSITIONED OVER WESTERN AUSTRALIA THROUGH 72H THEN TURN POLEWARD THROUGH 120H AS A DEEP MIDLATITUDE TROUGH APPROACHES AUSTRALIA.TC 26S IS FORECAST TO INTENSIFY STEADILY THROUGH THE FORECAST PERIOD TO A PEAK INTENSITY OF 105 KNOTS/US CAT 3 BY 96H WITH GRADUAL WEAKENING ANTICIPATED BY 120H.
26S(SEROJA). WARNING 7 ISSUED AT 06/03UTC.UPPER-LEVEL ANALYSIS REVEALS A MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE (15-20 KNOTS) VERTICAL WIND SHEAR OFFSET BY DIFFLUENT FLOW ALOFT. TC 26S IS FORECAST TO TRACK ALONG THE NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE POSITIONED OVER WESTERN AUSTRALIA THROUGH 72H THEN TURN POLEWARD THROUGH 120H AS A DEEP MIDLATITUDE TROUGH APPROACHES AUSTRALIA.TC 26S IS FORECAST TO INTENSIFY STEADILY THROUGH THE FORECAST PERIOD TO A PEAK INTENSITY OF 105 KNOTS/US CAT 3 BY 96H WITH GRADUAL WEAKENING ANTICIPATED BY 120H.

26S(SEROJA). NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT LENDING MODERATE CONFIDENCE TO THE JTWC FORECAST TRACK.
26S(SEROJA). NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT LENDING MODERATE CONFIDENCE TO THE JTWC FORECAST TRACK.

26S(SEROJA). 06/0220UTC. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A DEVELOPING CENTRAL DENSE OVERCAST OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC).
26S(SEROJA). 06/0220UTC. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A DEVELOPING CENTRAL DENSE OVERCAST OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC).

26(SEROJA). 05/2032UTC. SSMIS 91GHZ COLOR COMPOSITE IMAGE SHOWS A PARTIALLY-EXPOSED LLCC WITH THE UPPER-LEVEL CIRCULATION CENTER (MICROWAVE EYE FEATURE) TILTED TO THE WEST DUE TO EASTERLY VERTICAL WIND SHEAR.
26(SEROJA). 05/2032UTC. SSMIS 91GHZ COLOR COMPOSITE IMAGE SHOWS A PARTIALLY-EXPOSED LLCC WITH THE UPPER-LEVEL CIRCULATION CENTER (MICROWAVE EYE FEATURE) TILTED TO THE WEST DUE TO EASTERLY VERTICAL WIND SHEAR.


27S. WARNING 5 ISSUED AT 06/03UTC. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MODERATE NORTHEASTERLY VERTICAL WIND SHEAR OFFSET SLIGHTLY BY ENHANCED POLEWARD OUTFLOW. HOWEVER, ANIMATED WATER VAPOR IMAGERY INDICATES PULSES OF OUTFLOW FROM TC 26S IMPINGING ON THE NORTHWEST PERIPHERY OF THE SYSTEM. THE FORECAST PHILOSOPHY HAS BEEN REVISED SIGNIFICANTLY BASED ON THE LIKELY BINARY INTERACTION SCENARIO WITH THE LARGER, MORE DOMINANT TC 26S. TC 27S IS FORECAST TO DRIFT SLOWLY EASTWARD TO NORTHEASTWARD UNDER THE LOW-LEVEL NEAR- EQUATORIAL RIDGE TO THE NORTH THROUGH 36H. BY 48H,  TC 27S IS EXPECTED TO APPROACH WITHIN 780KM OF TC 26S, WHICH  WILL BECOME THE DOMINANT STEERING INFLUENCE THROUGH THE  REMAINDER OF THE FORECAST PERIOD. SPECIFICALLY, TC 27S WILL TURN EASTWARD THEN SOUTHEASTWARD AS IT ACCELERATES AROUND THE NORTHERN PERIPHERY OF TC 26S. THE SYSTEM WILL PEAK OPTIMISTICALLY AT 50 KNOTS BY 36H BUT WILL RAPIDLY DISSIPATE AFTER 48H AS IT BECOMES ABSORBED IN THE OUTER PERIPHERY OF TC 26S.
27S. WARNING 5 ISSUED AT 06/03UTC. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MODERATE NORTHEASTERLY VERTICAL WIND SHEAR OFFSET SLIGHTLY BY ENHANCED POLEWARD OUTFLOW. HOWEVER, ANIMATED WATER VAPOR IMAGERY INDICATES PULSES OF OUTFLOW FROM TC 26S IMPINGING ON THE NORTHWEST PERIPHERY OF THE SYSTEM. THE FORECAST PHILOSOPHY HAS BEEN REVISED SIGNIFICANTLY BASED ON THE LIKELY BINARY INTERACTION SCENARIO WITH THE LARGER, MORE DOMINANT TC 26S. TC 27S IS FORECAST TO DRIFT SLOWLY EASTWARD TO NORTHEASTWARD UNDER THE LOW-LEVEL NEAR- EQUATORIAL RIDGE TO THE NORTH THROUGH 36H. BY 48H, TC 27S IS EXPECTED TO APPROACH WITHIN 780KM OF TC 26S, WHICH WILL BECOME THE DOMINANT STEERING INFLUENCE THROUGH THE REMAINDER OF THE FORECAST PERIOD. SPECIFICALLY, TC 27S WILL TURN EASTWARD THEN SOUTHEASTWARD AS IT ACCELERATES AROUND THE NORTHERN PERIPHERY OF TC 26S. THE SYSTEM WILL PEAK OPTIMISTICALLY AT 50 KNOTS BY 36H BUT WILL RAPIDLY DISSIPATE AFTER 48H AS IT BECOMES ABSORBED IN THE OUTER PERIPHERY OF TC 26S.

27S. NUMERICAL MODEL GUIDANCE IS IN BETTER AGREEMENT WITH THE BULK OF THE SOLUTIONS SUPPORTING THE JTWC FORECAST TRACK,  HOWEVER, THERE IS LOW CONFIDENCE IN THE OVERALL FORECAST TRACK DUE TO WEAK STEERING / ERRATIC MOTION IN THE EARLY FORECAST  AND THE COMPLEX SCENARIO / BINARY INTERACTION.
27S. NUMERICAL MODEL GUIDANCE IS IN BETTER AGREEMENT WITH THE BULK OF THE SOLUTIONS SUPPORTING THE JTWC FORECAST TRACK, HOWEVER, THERE IS LOW CONFIDENCE IN THE OVERALL FORECAST TRACK DUE TO WEAK STEERING / ERRATIC MOTION IN THE EARLY FORECAST AND THE COMPLEX SCENARIO / BINARY INTERACTION.

27S. 06/0230UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A WELL- DEFINED LOW-LEVEL CIRCULATION CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE, WITH LIMITED BANDING OVER THE SOUTHERN SEMICIRCLE.
27S. 06/0230UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A WELL- DEFINED LOW-LEVEL CIRCULATION CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE, WITH LIMITED BANDING OVER THE SOUTHERN SEMICIRCLE.

27S. 05/2319UTC. SSMIS 91GHZ IMAGE REVEALS SHALLOW BANDING WRAPPING INTO THE EXPOSED CENTER WITH FRAGMENTED BANDING OVER THE EASTERN AND SOUTHERN SEMICIRCLES.
27S. 05/2319UTC. SSMIS 91GHZ IMAGE REVEALS SHALLOW BANDING WRAPPING INTO THE EXPOSED CENTER WITH FRAGMENTED BANDING OVER THE EASTERN AND SOUTHERN SEMICIRCLES.


06/03UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON 26S(SEROJA) AND 27S. 3HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.
06/03UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON 26S(SEROJA) AND 27S. 3HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.