TC 07S(CHALANE) intensifying over the MOZ Channel, Update 28/09UTC

2020 DEC 28 0955UTC #SOUTHINDIANOCEAN
TC #07S #CHALANE
WARNING 8
As of 06:00 UTC Dec 28, 2020:
Location: 20.3°S 43.7°E
Maximum Winds: 35 kt ( 65km/h)
Gusts: 45 kt ( 85km/h)
Minimum Central Pressure: 1007 mb
INTENSIFYING
Satellite bulletins are to be found in the comments of this post on JTWC BIS.
REMARKS:
280900Z POSITION NEAR 20.1S 43.3E.
28DEC20. TROPICAL CYCLONE 07S (CHALANE), LOCATED APPROXIMATELY
236 NM EAST-NORTHEAST OF EUROPA ISLAND, HAS TRACKED WEST-
SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION
FLARING TO THE NORTHWEST AND OVER THE ASSESSED LOW LEVEL CIRCULATION
CENTER (LLCC), WITH THE LOW LEVEL CLOUD BANDS EXPOSED ON THE
SOUTHERN SIDE. ANALYSIS OF THE EXPOSED LOW LEVEL CLOUD BANDS, AND A
280550Z ASCAT-A SCATTEROMETER PASS LEND HIGH CONFIDENCE TO THE
INITIAL POSITION. THE INITIAL INTENSITY IS HEDGED SLIGHTLY HIGHER
THAN THE PGTW DVORAK INTENSITY ESTIMATE OF T1.5 (25 KTS) BASED ON AN
ADT ESTIMATE OF T2.5 (35 KTS), A SATELLITE CONSENSUS ESTIMATE OF 36
KTS AND THE AFOREMENTIONED 280550Z ASCAT-A PASS, WHICH SHOWED A BAND
OF 30-35 KNOT WINDS STRETCHING FROM THE NORTHEAST TO SOUTHEAST
QUADRANTS, BETWEEN THE LLCC AND THE COASTLINE. ENVIRONMENTAL
ANALYSIS REVEALS GENERALLY SUPPORTIVE CONDITIONS, WITH LOW (<10 KTS)
VWS, AND VERY WARM (31-32C) SSTS, BEING OFFSET SOMEWHAT BY WEAK
OUTFLOW ALOFT, AS THE SYSTEM LIES DIRECTLY ALONG THE AXIS OF A 200
MB RIDGE EXTENDING FROM FAR NORTHERN SOUTH AFRICA TO NORTHEAST
MADAGASCAR. TC 07S CONTINUES TO TRACK WEST-SOUTHWESTWARD ALONG THE
NORTHWESTERN PERIPHERY OF A LOW TO MID-LEVEL STR LOCATED TO THE
SOUTHEAST OF MADAGASCAR. OVER THE NEXT 12 HOURS, THE STEERING
PATTERN IS EXPECTED TO CHANGE, WITH A BUILDING STR TO THE SOUTH OF
THE MOZAMBIQUE CHANNEL EXPECTED TO PRESUME THE DOMINANT STEERING
ROLE, SHIFTING TC 07S TO A WESTWARD TRACK THROUGH THE REMAINDER OF
THE FORECAST. NUMERICAL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH
THE ENTIRETY OF THE FORCAST PERIOD, WITH A MAXIMUM SPREAD OF 90NM AT
TAU 48, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THERE IS
HOWEVER SIGNIFICANT UNCERTAINTY IN THE INTENSITY GUIDANCE, WITH THE
HWRF NOW BACKING OFF THE RAPID INTENSIFICATION IT HAS BEEN
PREDICTING IN EARLIER RUNS, WHILE THE ECMWF AND COAMPS-TC SOLUTIONS
CONTINUE TO SHOW A PEAK INTENSITY NEAR 55 KNOTS. IN THE NEAR-TERM,
WEAK OUTFLOW AND MID-LEVEL DRY AIR WILL LIMIT THE OPPORTUNITY FOR
INTENSIFICATION THROUGH TAU 24. THERAFTER THE MID-LEVELS MOISTEN,
OUTFLOW SLOWLY IMPROVES AND THE SYSTEM MOVES OVER A POOL OF HIGH
OHC, ALLOWING FOR FASTER INTENSIFICATION THROUGH TAU 36. THE SYSTEM
IS EXPECTED TO REACH PEAK INTENSITY OF 65 KNOTS AT TAU 48 AS IT
MOVES THROUGH A VERY FAVORABLE ENVIRONMENT. THE ONLY FACTOR LIMITING
THE INTENSIFICATION IS THE AMOUNT OF OUTFLOW ALOFT, AND ANALYSIS OF
UPPER-LEVEL MODEL FIELDS LENDS SUPPORT TO A HIGHER INTENSITY THAN
THE INTENSITY GUIDANCE WOULD SUGGEST. THE COAMPS-TC ENSEMBLE
SUGGESTS A HIGH PROBABILITY OF INTENSIFICATION UP TO 65 KNOTS, WITH
A SLIGHT POSSIBILITY OF A HIGHER INTENSITY JUST PRIOR TO LANDFALL
NEAR BEIRA, MOZAMBIQUE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 280600Z
IS 12 FEET. NEXT WARNINGS AT 282100Z AND 290900Z.//
NNNN

Cheers,
Patrick Hoareau