SOUTH INDIAN: 26S(SEROJA) could reach US/CAT 3 by 96hours. 27S slow-moving 550km South of Christmas island, 05/03utc update

05/04/2021

05/03UTC. 5H LOOP. TC 26S(SEROJA) ON THE RIGHT AND TC 27S. IF NEEDED CLICK TO ANIMATE.

2021 APR 05 03UTC #SOUTHERNHEMISPHERE #SOUTHINDIANOCEAN
TC #26S #SEROJA  #WESTERNAUSTRALIA
WARNING 3
As of 00:00 UTC Apr 05, 2021:
Location: 10.6°S 122.6°E
Maximum Winds: 45 kt ( 85km/h)
Gusts: 55 kt ( 100km/h)
Minimum Central Pressure: 992 mb
INTENSIFYING
26S LOCATED AT 05/00UTC APPROXIMATELY 925 KM WEST-NORTHWEST OF DARWIN, AUSTRALIA, HAS TRACKED WEST-
SOUTHWESTWARD AT 07 KM/H OVER THE PAST SIX HOURS.
Satellite bulletins are to be found in the comments of this post on JTWC BIS
----------------------------------------------------------
TC 27S  #SOUTHINDIANOCEAN #WESTERNAUSTRALIA
UPDATE
As of 00:00 UTC Apr 05, 2021:
Location: 15.3°S 104.9°E
Maximum Winds: 35 kt ( 65km/h)
Gusts: 45 kt ( 85km/h)
Minimum Central Pressure: 998 mb
INTENSIFYING
27S LOCATED AT 05/00UTC APPROXIMATELY 540KM SOUTH OF CHRISTMAS ISLAND HAS TRACKED SOUTH-SOUTHEASTWARD AT 07KM/H OVER THE PAST 6 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

TC 26S(SEROJA). WARNING 3 ISSUED AT 05/03UTC.TC 26S IS IN A FAVORABLE ENVIRONMENT WITH GOOD RADIAL  OUTFLOW AND LOW TO MODERATE (10-15KT) VERTICAL WIND SHEAR(VWS) ALOFT, AND WARM (29C) SEA SURFACE TEMPERATURE (SST) IN THE SUVA SEA.  THE CYCLONE IS QUASI STATIONARY IN A COL TOWARD THE CENTER OF A NEAR EQUATORIAL  RIDGE (NER) TO THE NORTHWEST, A NER TO THE NORTHEAST, AND A  SUBTROPICAL RIDGE (STR) TO THE SOUTH. THE STR IS EXPECTED TO BUILD,  REORIENT TO THE SOUTHEAST AND SLOWLY DRIVE TC 26S SOUTHWESTWARD. THE  FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALONG THE FORECAST TRACK  AND PROMOTE STEADY INTENSIFICATION TO A PEAK OF 100KNOTS/US CAT 3 BY 96H.  AFTERWARD, INCREASING VWS AND COOLING SST WILL WEAKEN THE SYSTEM DOWN  TO 90KNOTS/CAT2 BY 120H AS THE CYCLONE TRACKS MORE SOUTHWARD IN RESPONSE  TO THE STEERING STR WEAKENING AND RECEDING EASTWARD.
TC 26S(SEROJA). WARNING 3 ISSUED AT 05/03UTC.TC 26S IS IN A FAVORABLE ENVIRONMENT WITH GOOD RADIAL OUTFLOW AND LOW TO MODERATE (10-15KT) VERTICAL WIND SHEAR(VWS) ALOFT, AND WARM (29C) SEA SURFACE TEMPERATURE (SST) IN THE SUVA SEA. THE CYCLONE IS QUASI STATIONARY IN A COL TOWARD THE CENTER OF A NEAR EQUATORIAL RIDGE (NER) TO THE NORTHWEST, A NER TO THE NORTHEAST, AND A SUBTROPICAL RIDGE (STR) TO THE SOUTH. THE STR IS EXPECTED TO BUILD, REORIENT TO THE SOUTHEAST AND SLOWLY DRIVE TC 26S SOUTHWESTWARD. THE FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALONG THE FORECAST TRACK AND PROMOTE STEADY INTENSIFICATION TO A PEAK OF 100KNOTS/US CAT 3 BY 96H. AFTERWARD, INCREASING VWS AND COOLING SST WILL WEAKEN THE SYSTEM DOWN TO 90KNOTS/CAT2 BY 120H AS THE CYCLONE TRACKS MORE SOUTHWARD IN RESPONSE TO THE STEERING STR WEAKENING AND RECEDING EASTWARD.

26S(SEROJA). NUMERICAL MODELS  ARE IN FAIRLY TIGHT AGREEMENT UP TO 48H. AFTERWARD, NOTABLE  SPREADING OCCURS TO OVER 540KM BY 120H WITH ECMF, EEMN, AND NVGM  ON THE RIGHT MARGIN OF THE ENVELOPE, LIKELY DUE TO EXCESSIVE BINARY  INTERACTION WITH TC 27S, CURRENTLY IN THE INDIAN OCEAN SOUTH OF  CHRISTMAS ISLAND, THAT IS PROJECTED TO APPROACH TC 26S TOWARD THE  EXTENDED FORECAST BUT WELL OUTSIDE OF 1110KM. THIS, AND THE UNCERTAINTY AS  TO WHEN THE SYSTEM MOVES OUT OF THE COL AND ITS QUASI STATONARY STATE, LEND  OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST THAT IS LAID OVER  BUT SLIGHTLY SLOWER THAN THE MODEL CONSENSUS UP TO 72H. AFTERWARD,  THE FORECAST TRACK IS LAID JUST LEFT OF THE CONSENSUS TO OFFSET THE  RIGHT MARGIN OUTLIERS.
26S(SEROJA). NUMERICAL MODELS ARE IN FAIRLY TIGHT AGREEMENT UP TO 48H. AFTERWARD, NOTABLE SPREADING OCCURS TO OVER 540KM BY 120H WITH ECMF, EEMN, AND NVGM ON THE RIGHT MARGIN OF THE ENVELOPE, LIKELY DUE TO EXCESSIVE BINARY INTERACTION WITH TC 27S, CURRENTLY IN THE INDIAN OCEAN SOUTH OF CHRISTMAS ISLAND, THAT IS PROJECTED TO APPROACH TC 26S TOWARD THE EXTENDED FORECAST BUT WELL OUTSIDE OF 1110KM. THIS, AND THE UNCERTAINTY AS TO WHEN THE SYSTEM MOVES OUT OF THE COL AND ITS QUASI STATONARY STATE, LEND OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST THAT IS LAID OVER BUT SLIGHTLY SLOWER THAN THE MODEL CONSENSUS UP TO 72H. AFTERWARD, THE FORECAST TRACK IS LAID JUST LEFT OF THE CONSENSUS TO OFFSET THE RIGHT MARGIN OUTLIERS.

26S(SEROJA). 05/0250UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A CONSOLIDATING SYSTEM EVEN AS  RAIN BANDS REMAIN FRAGMENTED AND WITH MINIMAL SEGMENTS OF DEEP  CONVECTION. THE CYCLONE REMAINS QUASI-STATIONARY IN THE SUVA SEA  JUST SOUTHWEST OF TIMOR.
26S(SEROJA). 05/0250UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A CONSOLIDATING SYSTEM EVEN AS RAIN BANDS REMAIN FRAGMENTED AND WITH MINIMAL SEGMENTS OF DEEP CONVECTION. THE CYCLONE REMAINS QUASI-STATIONARY IN THE SUVA SEA JUST SOUTHWEST OF TIMOR.

27S. WARNING 1 ISSUED AT 04/21UTC.ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE (15-20KT)  VERTICAL WIND SHEAR, ROBUST POLEWARD OUTFLOW ALOFT, AND WARM (29C)  SEA SURFACE TEMPERATURE. THESE ARE OFFSET BY COLD DRY AIR INTRUSION  FROM THE SOUTHWEST, AS INDICATED IN A RECENT TOTAL PRECIPITABLE WATER  LOOP. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A LOW  REFLECTION OF THE NEAR EQUATORIAL RIDGE (NER) TO THE NORTHEAST. AFTER  24H, TC 27S WILL TRACK MORE EASTWARD AS THE NER WEAKENS AND  RECEDES WESTWARD. AFTER 48H, THE SYSTEM WILL TURN MORE POLEWARD AS  A NEAR EQUATORIAL RIDGE TO THE SOUTHEAST ASSUMES STEERING.  CONCURRENTLY, A BINARY INTERACTION WITH TC 26S WILL COMMENCE. THE  MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A SLOW INTENSIFICATION TO  A PEAK OF 65KNOTS/US CAT 1. AFTERWARD, THE CYCLONE WILL RAPIDLY WEAKEN TO 50KNOTS  BY 120H AS OUTFLOW FROM TC 26S, BEING THE LARGER AND MORE DOMINANT  CYCLONE, WILL BEGIN TO SUPPRESS TC 27S.
27S. WARNING 1 ISSUED AT 04/21UTC.ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE (15-20KT) VERTICAL WIND SHEAR, ROBUST POLEWARD OUTFLOW ALOFT, AND WARM (29C) SEA SURFACE TEMPERATURE. THESE ARE OFFSET BY COLD DRY AIR INTRUSION FROM THE SOUTHWEST, AS INDICATED IN A RECENT TOTAL PRECIPITABLE WATER LOOP. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A LOW REFLECTION OF THE NEAR EQUATORIAL RIDGE (NER) TO THE NORTHEAST. AFTER 24H, TC 27S WILL TRACK MORE EASTWARD AS THE NER WEAKENS AND RECEDES WESTWARD. AFTER 48H, THE SYSTEM WILL TURN MORE POLEWARD AS A NEAR EQUATORIAL RIDGE TO THE SOUTHEAST ASSUMES STEERING. CONCURRENTLY, A BINARY INTERACTION WITH TC 26S WILL COMMENCE. THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A SLOW INTENSIFICATION TO A PEAK OF 65KNOTS/US CAT 1. AFTERWARD, THE CYCLONE WILL RAPIDLY WEAKEN TO 50KNOTS BY 120H AS OUTFLOW FROM TC 26S, BEING THE LARGER AND MORE DOMINANT CYCLONE, WILL BEGIN TO SUPPRESS TC 27S.

27S. THERE IS A LARGE DISCREPANCY  AMONG THE NUMERICAL MODELS DUE TO THE LARGE VARIANCE IN THE PROJECTED  TRACKS CAUSED BY DIFFERENT SOLUTIONS TO THE BINARY INTERACTION WITH  TC 26S, LENDING LOW CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS  LAID CLOSE TO THE MODEL CONSENSUS.
27S. THERE IS A LARGE DISCREPANCY AMONG THE NUMERICAL MODELS DUE TO THE LARGE VARIANCE IN THE PROJECTED TRACKS CAUSED BY DIFFERENT SOLUTIONS TO THE BINARY INTERACTION WITH TC 26S, LENDING LOW CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID CLOSE TO THE MODEL CONSENSUS.

05/03UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON TC 27S(SEROJA) AND 12HOURLY WARNINGS ON TC 27S. 3HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.
05/03UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON TC 27S(SEROJA) AND 12HOURLY WARNINGS ON TC 27S. 3HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.