Indian-S: Bongoyo W7
From
Weather Alert@21:1/175 to
All on Mon Dec 7 20:33:00 2020
WTIO30 FMEE 071819
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 7/3/20202021
1.A MODERATE TROPICAL STORM 3 (BONGOYO)
2.A POSITION 2020/12/07 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 15.4 S / 79.9 E
(FIFTEEN DECIMAL FOUR DEGREES SOUTH AND
SEVENTY NINE DECIMAL NINE DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 11 KT
3.A DVORAK ANALYSIS: 3.0/3.0/D 0.5/6 H
4.A CENTRAL PRESSURE: 994 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT
RADIUS OF MAXIMUM WINDS (RMW): 65 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 75 SE: 280 SW: 335 NW: 75
34 KT NE: 0 SE: 75 SW: 185 NW: 0
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2020/12/08 06 UTC: 16.8 S / 78.0 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 55 SE: 250 SW: 205 NW: 75
34 KT NE: 45 SE: 75 SW: 95 NW: 65
24H: 2020/12/08 18 UTC: 17.9 S / 77.0 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 55 SE: 205 SW: 185 NW: 75
34 KT NE: 45 SE: 55 SW: 85 NW: 65
36H: 2020/12/09 06 UTC: 18.8 S / 76.4 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 45 SE: 130 SW: 165 NW: 75
34 KT NE: 35 SE: 100 SW: 75 NW: 65
48H: 2020/12/09 18 UTC: 19.2 S / 75.4 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 45 SE: 215 SW: 110 NW: 75
34 KT NE: 35 SE: 85 SW: 45 NW: 65
60H: 2020/12/10 06 UTC: 19.3 S / 73.8 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 35 SE: 95 SW: 120 NW: 55
72H: 2020/12/10 18 UTC: 19.2 S / 71.8 E, VENT MAX= 025 KT, FILLING UP
2.B LONGER-RANGE OUTLOOK:
96H: 2020/12/11 18 UTC: 18.7 S / 65.6 E, VENT MAX= 025 KT, REMNANT
LOW
2.C ADDITIONAL INFORMATION:
T=CI=3.0-
DURING THE LAST 6 HOURS, THE BONGOYO CLOUD CONFIGURATION HAS EVOLVED
FROM A CURVED BAND CONFIGURATION TO A SHEARED CONFIGURATION TO
FINALLY BECOME A CDO PATTERN WHOSE CENTER IS LOCATED AT THE EASTERN
EDGE OF THE CDO. THIS EVOLUTION IS CERTAINLY RELATED TO A MODERATE
WINDSHEAR OF THE MIDDLE TROPOSPHERE ACCOMPANIED BY AN INTRUSION OF
DRY AIR WHICH WEAKENED THE CONVECTION. THIS HAS BROKEN THE CONVECTIVE
CENTER OF THE CURVED BAND STILL PRESENT FURTHER EAST OF THE SYSTEM.
THE DVORAK ANALYSIS CAN BE REVISED SLIGHTLY UPWARDS WITH A CI OF 3.0
LEAVING WINDS OF THE ORDER OF 40KT VALIDATED LOCALLY BY THE 1531UTC
ASCAT SWATH.
LIMITED CHANGE IN THE PHILOSOPHY OF THE TRACK FORECAST: BONGOYO
MAINTAINS A SOUTHWEST TRACK UNDER THE INFLUENCE OF THE SUBTROPICAL
RIDGE FURTHER SOUTH. WITH THE PASSAGE FURTHER SOUTH OF A TROUGH, THE SUBTROPICAL RIDGE INDUCES A LESS MARKED DIRECTIONAL FLOW: THE TRACK
SLOWS DOWN AND TAKES ON A MORE MARKED MERIDIONAL COMPONENT BY MIDDAY
ON TUESDAY. IN MID-WEEK, A NEW SUBTROPICAL RIDGE IS POSITIONED
SOUTHWEST OF BONGOYO AGAIN IMPOSING A WESTWARD TRACK WHICH
ACCELERATES.
DURING THIS DISPLACEMENT, BONGOYO SEEMS TO HAVE FINISHED BENEFITING
FROM ITS FAVORABLE WINDOW, WITH THE REINFORCEMENT OF THE CONSTRAINT
IN THE MIDDLE TROPOSPHERE. THIS CONSTRAINT WILL GRADUALLY LIMIT THE
DEVELOPMENT OF THE SYSTEM ON TUESDAY. ON WEDNESDAY, THE DEEP VERTICAL
SHEAR SHOULD ALSO INCREASE AND BE ASSOCIATED WITH GREATER DRY
INTRUSIONS. THE SYSTEM SHOULD THEN RAPIDLY EVOLVE INTO A REMNANT LOW
AS IT MOVES TOWARDS THE MASCARENE ISLANDS.
=
--- SBBSecho 3.11-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)