South Pacific: 23P(NIRAN) US/Cat 4,still intensifying likely above the forecast/South Indian: 24S(HABANA): explosive intensification,05/09utc updates


23P(NIRAN). 05/09UTC. ENHANCED INFRA-RED ANIMATION SHOWS COOLING CLOUD TOPS AROUND THE WELL DEFINED EYE .THE SATELLITE SIGNATURE IS NOW IMPRESSIVE FOR THIS COMPACT SYSTEM. THE CYCLONE IS STILL INTENSIFYING. DVORAK ANALYSIS FROM PGTW(JTWC) IS AT 7.0/7.0 AT 05/0850UTC. IF NEEDED CLICK TO ANIMATE.


23P(NIRAN). 05/09UTC. ENHANCED INFRA-RED ANIMATION SHOWS COOLING CLOUD TOPS AROUND THE WELL DEFINED EYE .THE SATELLITE SIGNATURE IS NOW IMPRESSIVE FOR THIS COMPACT SYSTEM. THE CYCLONE IS STILL INTENSIFYING. DVORAK ANALYSIS FROM PGTW(JTWC) IS AT 7.0/7.0 AT 05/0850UTC. IF NEEDED CLICK TO ANIMATE.
23P(NIRAN). 05/09UTC. ENHANCED INFRA-RED ANIMATION SHOWS COOLING CLOUD TOPS AROUND THE WELL DEFINED EYE .THE SATELLITE SIGNATURE IS NOW IMPRESSIVE FOR THIS COMPACT SYSTEM. THE CYCLONE IS STILL INTENSIFYING. DVORAK ANALYSIS FROM PGTW(JTWC) IS AT 7.0/7.0 AT 05/0850UTC. IF NEEDED CLICK TO ANIMATE.
2021 MAR 05 09UTC #SOUTHERNHEMISPHERE
TC #23P #NIRAN  #SOUTHPACIFICOCEAN #CORALSEA
WARNING 18
As of 06:00 UTC Mar 05, 2021:
Location: 17.8°S 156.8°E
Maximum Winds: 115 kt ( 215km/h)
Gusts: 140 kt ( 260km/h)
Minimum Central Pressure: 940mb
CATEGORY US: 4
INTENSIFYING
LOCATED AT 05/06UTC APPROXIMATELY 1080KM WEST-NORTHWEST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EAST-
SOUTHEASTWARD AT 44 KM/H OVER THE PAST SIX HOURS.

 Satellite bulletins are to be found in the comments of this post on JTWC BIS
----------------------------------------------------------------------------------------------------------------------
TC #24S #HABANA  #SOUTHINDIANOCEAN
WARNING 3
As of 06:00 UTC Mar 05, 2021:
Location: 16.4°S 75.5°E
Maximum Winds: 90 kt (165km/h)
Gusts: 110 kt ( 205km/h)
Minimum Central Pressure: 972 mb
CATEGORY US: 2
INTENSIFYING
LOCATED AT 05/06UTC APPROXIMATELY 1085KM SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED EASTWARD AT 19
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
 Météo974
M974World
Cyclone Class 4
 Cheers,PH.

Joint Typhoon Warning Center

23P(NIRAN). WARNING 18 ISSUED AT 05/09UTC. TC 23P IS RAPIDLY MOVING SOUTHEASTWARD ALONG THE  SOUTHWESTERN PERIPHERY OF A COMBINED NEAR EQUATORIAL AND SUBTROPICAL  RIDGE COMPLEX CENTERED TO THE NORTHEAST. THE ENVIRONMENT REMAINS  FAVORABLE FOR THE MOMENT WITH MODERATE (20-25 KT) VERTICAL WIND SHEAR BEING OFFSET  BY VERY STRONG POLEWARD OUTFLOW AND WARM (29C) SSTS. THE SYSTEM IS  FORECAST TO CONTINUE TRACKING SOUTHEASTWARD THROUGH 48H ALONG THE  TIGHT GRADIENT BETWEEN THE RIDGE COMPLEX TO THE NORTHEAST AND AN  APPROACHING MAJOR SHORTWAVE TROUGH TO THE WEST. BY THE END OF THE  FORECAST, THE SYSTEM WILL MOVE SLIGHTLY MORE EASTWARD AS IT COMES  UNDER THE STEERING INFLUENCE OF A DYNAMIC LOW TO MID-LEVEL  ANTICYCLONE TO THE SOUTH. IN THE NEAR-TERM, GOOD ENVIRONMENTAL  CONDITIONS WILL SUPPORT ADDITIONAL INTENSIFICATION TO A PEAK OF 120  KNOTS/US CATEGORY 4 BY12H. THEREAFTER, ENVIRONMENTAL CONDITIONS BEGIN TO  RAPIDLY DETERIORATE AS THE VERTICAL WIND SHEAR INCREASES TO AN EXTENT THAT THE  OUTFLOW CANNOT OVERCOME AND THE CORE BECOMES DISRUPTED. AFTER 48H, VERTICAL WIND SHEAR WEAKENS SLIGHTLY, BUT DRY AIR ENTRAINMENT AND COOL SSTS AT  OR BELOW 26C WILL SERVE TO FURTHER WEAKEN THE SYSTEM AS IT BEGINS  SUBTROPICAL TRANSITION. THE TRANSITION TO A STORM FORCE SUBTROPICAL  SYSTEM WILL BE COMPLETE NO LATER THAN, AND POSSIBLY EARLIER THAN, 72H.
23P(NIRAN). WARNING 18 ISSUED AT 05/09UTC. TC 23P IS RAPIDLY MOVING SOUTHEASTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A COMBINED NEAR EQUATORIAL AND SUBTROPICAL RIDGE COMPLEX CENTERED TO THE NORTHEAST. THE ENVIRONMENT REMAINS FAVORABLE FOR THE MOMENT WITH MODERATE (20-25 KT) VERTICAL WIND SHEAR BEING OFFSET BY VERY STRONG POLEWARD OUTFLOW AND WARM (29C) SSTS. THE SYSTEM IS FORECAST TO CONTINUE TRACKING SOUTHEASTWARD THROUGH 48H ALONG THE TIGHT GRADIENT BETWEEN THE RIDGE COMPLEX TO THE NORTHEAST AND AN APPROACHING MAJOR SHORTWAVE TROUGH TO THE WEST. BY THE END OF THE FORECAST, THE SYSTEM WILL MOVE SLIGHTLY MORE EASTWARD AS IT COMES UNDER THE STEERING INFLUENCE OF A DYNAMIC LOW TO MID-LEVEL ANTICYCLONE TO THE SOUTH. IN THE NEAR-TERM, GOOD ENVIRONMENTAL CONDITIONS WILL SUPPORT ADDITIONAL INTENSIFICATION TO A PEAK OF 120 KNOTS/US CATEGORY 4 BY12H. THEREAFTER, ENVIRONMENTAL CONDITIONS BEGIN TO RAPIDLY DETERIORATE AS THE VERTICAL WIND SHEAR INCREASES TO AN EXTENT THAT THE OUTFLOW CANNOT OVERCOME AND THE CORE BECOMES DISRUPTED. AFTER 48H, VERTICAL WIND SHEAR WEAKENS SLIGHTLY, BUT DRY AIR ENTRAINMENT AND COOL SSTS AT OR BELOW 26C WILL SERVE TO FURTHER WEAKEN THE SYSTEM AS IT BEGINS SUBTROPICAL TRANSITION. THE TRANSITION TO A STORM FORCE SUBTROPICAL SYSTEM WILL BE COMPLETE NO LATER THAN, AND POSSIBLY EARLIER THAN, 72H.

23P(NIRAN). NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH 24H  BUT CROSS AND ALONG-TRACK UNCERTAINTY INCREASES SIGNIFICANTLY  THEREAFTER. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN THROUGH  24H, THEN NEAR THE ECMWF TRACK THROUGH THE REMAINDER OF THE  FORECAST PERIOD. OVERALL THERE IS HIGH CONFIDENCE IN THE FIRST 24  HOURS OF THE FORECAST, AND LOW CONFIDENCE THEREAFTER.
23P(NIRAN). NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH 24H BUT CROSS AND ALONG-TRACK UNCERTAINTY INCREASES SIGNIFICANTLY THEREAFTER. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN THROUGH 24H, THEN NEAR THE ECMWF TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD. OVERALL THERE IS HIGH CONFIDENCE IN THE FIRST 24 HOURS OF THE FORECAST, AND LOW CONFIDENCE THEREAFTER.

23P(NIRAN). 05/0614UTC. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS/US CATEGORY 4, HEDGED SLIGHTLY LOWER  THAN A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T6.5 (127 KTS) AND  CLOSELY ALIGNED TO A 114 KNOT WIND SPEED MEASUREMENT FROM A 050227Z  AMSR2 PASS.
23P(NIRAN). 05/0614UTC. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS/US CATEGORY 4, HEDGED SLIGHTLY LOWER THAN A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T6.5 (127 KTS) AND CLOSELY ALIGNED TO A 114 KNOT WIND SPEED MEASUREMENT FROM A 050227Z AMSR2 PASS.

23P(NIRAN). 05/0630UTC.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE EMERGENCE OF A VERY WELL  DEFINED 22KM EYE BY 0600UTC.
23P(NIRAN). 05/0630UTC.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE EMERGENCE OF A VERY WELL DEFINED 22KM EYE BY 0600UTC.

23P(NIRAN). 05/0630UTC.MICROWAVE IMAGE SHOWED THAT THE DEEP CONVECTION DOES NOT EXTEND ALL THE WAY  AROUND THE SYSTEM, WITH A DISTINCT BREAK IN THE EYEWALL ON THE  SOUTHEASTERN SIDE, INDICATIVE OF INCREASING EASTERLY WIND SHEAR. THE  INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON BOTH THE  SSMIS MICROWAVE IMAGE AND THE 19KM EYE IN THE INFRARED IMAGERY.
23P(NIRAN). 05/0630UTC.MICROWAVE IMAGE SHOWED THAT THE DEEP CONVECTION DOES NOT EXTEND ALL THE WAY AROUND THE SYSTEM, WITH A DISTINCT BREAK IN THE EYEWALL ON THE SOUTHEASTERN SIDE, INDICATIVE OF INCREASING EASTERLY WIND SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON BOTH THE SSMIS MICROWAVE IMAGE AND THE 19KM EYE IN THE INFRARED IMAGERY.

23P(NIRAN). ROBUST POLEWARD DIVERGENCE HAS CONTRIBUTED TO THE INTENSITY SPIKE.
23P(NIRAN). ROBUST POLEWARD DIVERGENCE HAS CONTRIBUTED TO THE INTENSITY SPIKE.


24S(HABANA). WARNING 3 ISSUED AT 05/09UTC. DUE TO THE EXTREMELY RAPID INTENSIFICATION (ERI),THE ENVIRONMENT IS OBVIOUSLY VERY FAVORABLE WITH VERY LOW  (5-7 KTS) WIND SHEAR, STRONG POLEWARD AND MODERATE EQUATORWARD OUTFLOW AND  WARM (29-30C) SSTS. TC 24S IS CURRENTLY TRACKING ALONG THE SOUTHERN  PERIPHERY OF A STRONG NEAR EQUATORIAL RIDGE (NER) ENTRENCHED TO THE  NORTH. THE SYSTEM IS EXPECTED TO CONTINUE TRACKING EAST-NORTHEAST  THROUGH 24H BUT TURN EAST AS THE NER FLATTENS OUT BY 24H.  THROUGH 72H A STR BUILDS EQUATORWARD TO THE EAST, FORCING A TURN  TO THE SOUTH. THEREAFTER A STRONG STR WILL BUILD IN TO THE SOUTH AND  TURN TC 24S ONTO A WESTWARD TRACK THROUGH THE REMAINDER OF THE  FORECAST. WHILE THERE IS HIGH UNCERTAINTY IN THE INTENSITY FORECAST  DUE TO THE UNEXPECTED ERI, THE RAPID INTENSIFICATION GUIDANCE IS  STILL BEING TRIPPED AND THE PRESENCE OF THE CYAN RING IN THE 37GHZ  MICROWAVE IMAGERY IS INDICATIVE OF POSSIBLE ADDITIONAL DEVELOPMENT.  THE FORECAST CALLS FOR THE SYSTEM TO REACH A PEAK OF 100 KNOTS/US CATEGORY 3 BY 12H BEFORE STARTING A SLOW WEAKENING TREND THROUGH THE REMAINDER OF  THE FORECAST, PRIMARILY IN RESPONSE TO A DECREASE IN UPPER-LEVEL  OUTFLOW AND SOME MID-LEVEL DRY AIR ENTRAINMENT.
24S(HABANA). WARNING 3 ISSUED AT 05/09UTC. DUE TO THE EXTREMELY RAPID INTENSIFICATION (ERI),THE ENVIRONMENT IS OBVIOUSLY VERY FAVORABLE WITH VERY LOW (5-7 KTS) WIND SHEAR, STRONG POLEWARD AND MODERATE EQUATORWARD OUTFLOW AND WARM (29-30C) SSTS. TC 24S IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A STRONG NEAR EQUATORIAL RIDGE (NER) ENTRENCHED TO THE NORTH. THE SYSTEM IS EXPECTED TO CONTINUE TRACKING EAST-NORTHEAST THROUGH 24H BUT TURN EAST AS THE NER FLATTENS OUT BY 24H. THROUGH 72H A STR BUILDS EQUATORWARD TO THE EAST, FORCING A TURN TO THE SOUTH. THEREAFTER A STRONG STR WILL BUILD IN TO THE SOUTH AND TURN TC 24S ONTO A WESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST. WHILE THERE IS HIGH UNCERTAINTY IN THE INTENSITY FORECAST DUE TO THE UNEXPECTED ERI, THE RAPID INTENSIFICATION GUIDANCE IS STILL BEING TRIPPED AND THE PRESENCE OF THE CYAN RING IN THE 37GHZ MICROWAVE IMAGERY IS INDICATIVE OF POSSIBLE ADDITIONAL DEVELOPMENT. THE FORECAST CALLS FOR THE SYSTEM TO REACH A PEAK OF 100 KNOTS/US CATEGORY 3 BY 12H BEFORE STARTING A SLOW WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST, PRIMARILY IN RESPONSE TO A DECREASE IN UPPER-LEVEL OUTFLOW AND SOME MID-LEVEL DRY AIR ENTRAINMENT.

24S(HABANA). NUMERICAL MODEL GUIDANCE IS IN POOR AGREEMENT BUT OVERALL AGREES ON THE OVERALL  SCENARIO. SPREAD INCREASES TO 280KM AT 48H, INCREASING TO 410KM  AT 120H. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN WITH LOW  CONFIDENCE.
24S(HABANA). NUMERICAL MODEL GUIDANCE IS IN POOR AGREEMENT BUT OVERALL AGREES ON THE OVERALL SCENARIO. SPREAD INCREASES TO 280KM AT 48H, INCREASING TO 410KM AT 120H. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN WITH LOW CONFIDENCE.

24S(HABANA). 05/0815UTC.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THAT TC 24S HAS UNDERGONE A CYCLE OF  EXTREMELY RAPID INTENSIFICATION (ERI) OVER THE PREVIOUS SIX HOURS. A  SMALL 19KM WIDE EYE FEATURE DEVELOPED JUST PRIOR TO 0600UTC WITH DEEP  CONVECTION COMPLETELY SURROUNDING THE VERY SMALL AND INTENSE CORE.
24S(HABANA). 05/0815UTC.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THAT TC 24S HAS UNDERGONE A CYCLE OF EXTREMELY RAPID INTENSIFICATION (ERI) OVER THE PREVIOUS SIX HOURS. A SMALL 19KM WIDE EYE FEATURE DEVELOPED JUST PRIOR TO 0600UTC WITH DEEP CONVECTION COMPLETELY SURROUNDING THE VERY SMALL AND INTENSE CORE.


24S(HABANA). 05/0815UTC.
24S(HABANA). 05/0815UTC.

24S(HABANA). 05/0630UTC. A  050630Z GMI 89GHZ MICROWAVE IMAGE CONFIRMED THE VERY WELL DEFINED  EYE SURROUNDED BY DEEP CONVECTION. THE 37GHZ IMAGE CONFIRMED THE  PRESENCE OF THE STRONG CYAN RING SIGNATURE, INDICATIVE OF THE RECENT  RAPID INTENSIFICATION AND HINTING AT THE POTENTIAL FOR SOME  ADDITIONAL DEVELOPMENT IN THE NEAR TERM.
24S(HABANA). 05/0630UTC. A 050630Z GMI 89GHZ MICROWAVE IMAGE CONFIRMED THE VERY WELL DEFINED EYE SURROUNDED BY DEEP CONVECTION. THE 37GHZ IMAGE CONFIRMED THE PRESENCE OF THE STRONG CYAN RING SIGNATURE, INDICATIVE OF THE RECENT RAPID INTENSIFICATION AND HINTING AT THE POTENTIAL FOR SOME ADDITIONAL DEVELOPMENT IN THE NEAR TERM.

24S(HABANA). THE CYCLONE IS TRACKING OVER A POOL OF WATER WITH HIGH OCEAN HEAT CONTENT.
24S(HABANA). THE CYCLONE IS TRACKING OVER A POOL OF WATER WITH HIGH OCEAN HEAT CONTENT.
Rédigé par PATRICK HOAREAU le Vendredi 5 Mars 2021 à 13:30