South Indian: 21S(GUAMBE) forecast to intensify to US/Category 2 by 48hours, 18/09utc update


21S(GUAMBE). 18/07UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A STEADILY IMPROVING CONVECTIVE SIGNATURE WITH WEAK CYCLONIC BANDING FEATURES BECOMING EVIDENT WITHIN THE CENTRAL DENSE OVERCAST (CDO) WHICH IS OBSCURING THE LOW LEVEL CIRCUATION CENTER (LLCC). CLICK ON THE IMAGERY TO ANIMATE IF NEEEDED.


21S(GUAMBE). 18/07UTC. ANIMATED MULTISPECTRAL SATELLITE  IMAGERY DEPICTS A STEADILY IMPROVING CONVECTIVE SIGNATURE WITH WEAK  CYCLONIC BANDING FEATURES BECOMING EVIDENT WITHIN THE CENTRAL DENSE  OVERCAST (CDO) WHICH IS OBSCURING THE LOW LEVEL CIRCUATION CENTER  (LLCC).
21S(GUAMBE). 18/07UTC. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A STEADILY IMPROVING CONVECTIVE SIGNATURE WITH WEAK CYCLONIC BANDING FEATURES BECOMING EVIDENT WITHIN THE CENTRAL DENSE OVERCAST (CDO) WHICH IS OBSCURING THE LOW LEVEL CIRCUATION CENTER (LLCC).
2021 FEB 18 08UTC #SOUTHERNHEMISPHERE
TC #21S #GUAMBE  #SOUTHINDIANOCEAN #MOZAMBIQUECHANNEL
WARNING 2
As of 06:00 UTC Feb 18, 2021:
Location: 22.6°S 37.7°E
Maximum Winds: 50 kt (95km/h)
Gusts: 65 kt ( 120km/h)
Minimum Central Pressure: 991 mb
INTENSIFYING
21S (GUAMBE), LOCATED AT 18/06UTC APPROXIMATELY 260KM WEST OF EUROPA ISLAND, HAS TRACKED SOUTH-SOUTHEASTWARD AT 07 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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Patrick Hoareau
 Météo974
M974World
Cyclone Class 4
 Cheers,PH.

Joint Typhoon Warning Center

21S(GUAMBE). WARNING 2 ISSUED AT 18/09UTC.  ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS WITH A  DEVELOPING POINT SOURCE DIRECTLY OVER THE LLOW LEVEL CENTER PROVIDING LOW (5-10  KTS) WIND SHEAR, MODERATE TO STRONG, NEARLY RADIAL OUTFLOW AND WARM (29- 30C) SSTS. TC 21S IS CURRENTLY ENSCONCED BETWEEN A BUILDING  SUBTROPICAL RIDGE (STR) CENTER OVER NORTHERN MADACASGAR AND A  SECONDARY STR CENTER OVER NORTHERN SOUTH AFRICA, RESULTING IN SLOW  MOVEMENT SOUTHWARD. OVER THE NEXT 12-24 HOURS, THE EASTERN STR IS  EXPECTED TO BUILD SUFFICIENTLY TO BECOME THE DOMINATE STEERING  MECHANISM AND TURN TC 21S TO A WEST-SOUTHWESTWARD TRACK. AS THE STR  MOVES SOUTH-SOUTHEASTWARD THROUGH 48H, TC 21S WILL ACCELERATE  SOUTH THEN SOUTHEASTWARD AS IT ROUNDS THE RIDGE AXIS. AFTER 72H  THE SYSTEM RAPIDLY ACCELERATES SOUTHEASTWARD ALONG THE BAROCLINIC  ZONE AS IT BEGINS TO INTERACT WITH STRONG MID-LATITUDE WESTERLY FLOW  ALOFT. TC 21S IS EXPECTED TO STEADILY INTENSIFY UNDER FAVORABLE  CONDITIONS TO A PEAK OF 85 KNOTS/CATEGORY 2 BY 48H, THEN MAINTAIN INTENSITY  THROUGH 72H. THEREAFTER, INCREASING WIND SHEAR WILL OFFSET THE STRONG  POLEWARD OUTFLOW, LEADING TO SLOW WEAKENING. TC 21S WILL BEGIN  EXTRATROPICAL TRANSITION BY 96H, AND BECOME A STORM-FORCE  EXTRATROPICAL SYSTEM BY 120H.
21S(GUAMBE). WARNING 2 ISSUED AT 18/09UTC. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS WITH A DEVELOPING POINT SOURCE DIRECTLY OVER THE LLOW LEVEL CENTER PROVIDING LOW (5-10 KTS) WIND SHEAR, MODERATE TO STRONG, NEARLY RADIAL OUTFLOW AND WARM (29- 30C) SSTS. TC 21S IS CURRENTLY ENSCONCED BETWEEN A BUILDING SUBTROPICAL RIDGE (STR) CENTER OVER NORTHERN MADACASGAR AND A SECONDARY STR CENTER OVER NORTHERN SOUTH AFRICA, RESULTING IN SLOW MOVEMENT SOUTHWARD. OVER THE NEXT 12-24 HOURS, THE EASTERN STR IS EXPECTED TO BUILD SUFFICIENTLY TO BECOME THE DOMINATE STEERING MECHANISM AND TURN TC 21S TO A WEST-SOUTHWESTWARD TRACK. AS THE STR MOVES SOUTH-SOUTHEASTWARD THROUGH 48H, TC 21S WILL ACCELERATE SOUTH THEN SOUTHEASTWARD AS IT ROUNDS THE RIDGE AXIS. AFTER 72H THE SYSTEM RAPIDLY ACCELERATES SOUTHEASTWARD ALONG THE BAROCLINIC ZONE AS IT BEGINS TO INTERACT WITH STRONG MID-LATITUDE WESTERLY FLOW ALOFT. TC 21S IS EXPECTED TO STEADILY INTENSIFY UNDER FAVORABLE CONDITIONS TO A PEAK OF 85 KNOTS/CATEGORY 2 BY 48H, THEN MAINTAIN INTENSITY THROUGH 72H. THEREAFTER, INCREASING WIND SHEAR WILL OFFSET THE STRONG POLEWARD OUTFLOW, LEADING TO SLOW WEAKENING. TC 21S WILL BEGIN EXTRATROPICAL TRANSITION BY 96H, AND BECOME A STORM-FORCE EXTRATROPICAL SYSTEM BY 120H.

ALL MEMBERS OF THE CONSENSUS CONCUR  ON THE OVERALL FORECAST TRACK SCENARIO BUT DISPLAY SIGNIFICANT CROSS TRACK  UNCERTAINTY THOUGH 48H, WITH NAVGEM AND THE COAMPS-TC TAKING THE  SYSTEM MUCH CLOSER TO THE COAST OF MOZAMBIQUE, AND THE GFS AND ECMWF  KEEPING THE SYSTEM WELL OFFSHORE IN THE MOZAMBIQUE CHANNEL. AFTER  72H, THE PACE AND STRENGTH OF THE INTERACTION WITH THE WESTERLIES  RESULT IN EXTREMELY LARGE ALONG-TRACK UNCERTAINTY, WITH THE GFS,  UKMET AND ECMWF WELL OUT AHEAD (1480KM) OF THE REMAINING MEMBERS OF  THE CONSENSUS. THE JTWC FORECAST TRACKS CLOSE TO THE ECMWF THROUGH  48H, BUT CLOSER TO THE NAVGEM THROUGH 120H. OVERALL THE JTWC  FORECAST IS MUCH FASTER AFTER 72H THAN THE PREVIOUS FORECAST. DUE  TO THE VERY HIGH UNCERTAINTY IN THE LATER PORTIONS OF THE FORECAST,  THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK.
ALL MEMBERS OF THE CONSENSUS CONCUR ON THE OVERALL FORECAST TRACK SCENARIO BUT DISPLAY SIGNIFICANT CROSS TRACK UNCERTAINTY THOUGH 48H, WITH NAVGEM AND THE COAMPS-TC TAKING THE SYSTEM MUCH CLOSER TO THE COAST OF MOZAMBIQUE, AND THE GFS AND ECMWF KEEPING THE SYSTEM WELL OFFSHORE IN THE MOZAMBIQUE CHANNEL. AFTER 72H, THE PACE AND STRENGTH OF THE INTERACTION WITH THE WESTERLIES RESULT IN EXTREMELY LARGE ALONG-TRACK UNCERTAINTY, WITH THE GFS, UKMET AND ECMWF WELL OUT AHEAD (1480KM) OF THE REMAINING MEMBERS OF THE CONSENSUS. THE JTWC FORECAST TRACKS CLOSE TO THE ECMWF THROUGH 48H, BUT CLOSER TO THE NAVGEM THROUGH 120H. OVERALL THE JTWC FORECAST IS MUCH FASTER AFTER 72H THAN THE PREVIOUS FORECAST. DUE TO THE VERY HIGH UNCERTAINTY IN THE LATER PORTIONS OF THE FORECAST, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK.

21S(GUAMBE). 18/08UTC. INTENSIFYING SYSTEM. Eumetsat. Enhanced by Patrick Hoareau.
21S(GUAMBE). 18/08UTC. INTENSIFYING SYSTEM. Eumetsat. Enhanced by Patrick Hoareau.


18/06UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON 01W AND 12HOURLY WARNINGS ON 21S. 3 HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.
18/06UTC. JTWC IS ISSUING 6HOURLY WARNINGS ON 01W AND 12HOURLY WARNINGS ON 21S. 3 HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.
Rédigé par PATRICK HOAREAU le Jeudi 18 Février 2021 à 12:30