SIO: INVEST 96S

[Nancy Smar]

96S INVEST 1800 4.0S 74.0E SHEM 15 0

[Nancy Smar]

PART 2 :
TROPICAL WEATHER DISCUSSION:
Currently, an equatorial Rossby wave transits from east to west and favors a wide cyclonic circulation centred approximatively near 4.2S/75.2E. Deep convective activity is strong but very fluctuating over the southern semi-circle within the polerward low level feeding between 65E and 80E. According with the 0346Z ASCAT swath, maximum winds are estimated at 15 kt but reaching 25/30 kt far from the centre by gradient effect. Minimal pressure is estimated at 1005 hPa.
Environmental conditions remain unfavourable due to a weak low level equatorward convergence and especially a strong eastern to northeastern vertical windshear. Model guidance are in good agreement to forecast a soutsouthwestward moving. On this track, the vertical windshear is expected to temporally decrease Wednesday and Thursday ahead a deep mid-latitudes upper level trough. With an improving upper level divergence, the LLCC should slightly deepen although the environment should become drier and drier. But, from Friday, behind the upper level trough, the western vertical windshear is forecasted to become moderate and the LLCC should begin to fill up drifting within the trade winds.
The risk of development of a moderate tropical storm is low south-west of Diego-Garcia.

[wxman57]

Overnight ScatSat had a well-defined LLC with 35kt winds. It appears to be an unclassified tropical storm.

[Nancy Smar]

MMS：Tropical Depression

[wxman57]

MMS：Tropical Depression

What agency is MMS? La Reunion is giving this system only a slight chance of developing. Recent scatterometer data indicate it's a tropical cyclone with 35-40 kt winds.

[TorSkk]

MMS：Tropical Depression

What agency is MMS? La Reunion is giving this system only a slight chance of developing. Recent scatterometer data indicate it's a tropical cyclone with 35-40 kt winds.

Mauritius Meteorological Services, they name systems west of 55 E

[wxman57]

MMS：Tropical Depression

What agency is MMS? La Reunion is giving this system only a slight chance of developing. Recent scatterometer data indicate it's a tropical cyclone with 35-40 kt winds.

Mauritius Meteorological Services, they name systems west of 55 E

Ah, they're not the RSMC for the SW Indian Ocean. La Reunion is responsible for classifying systems there.

[TorSkk]

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 1/1/20192020
1.A ZONE OF DISTURBED WEATHER 1
2.A POSITION 2019/07/23 AT 1800 UTC:
WITHIN 40 NM RADIUS OF POINT 13.5 S / 68.6 E
(THIRTEEN DECIMAL FIVE DEGREES SOUTH AND
SIXTY EIGHT DECIMAL SIX DEGREES EAST)
MOVEMENT: SOUTH-WEST 15 KT
3.A DVORAK ANALYSIS: NIL
4.A CENTRAL PRESSURE: 1002 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 25 KT
RADIUS OF MAXIMUM WINDS (RMW): 278 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
NIL
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 1100 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: SHALLOW
1.B FORECASTS:
12H: 2019/07/24 06 UTC: 15.3 S / 68.0 E, VENT MAX= 030 KT, TROPICAL DEPRESSION
24H: 2019/07/24 18 UTC: 17.3 S / 68.3 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
36H: 2019/07/25 06 UTC: 18.8 S / 67.5 E, VENT MAX= 030 KT, TROPICAL DEPRESSION
48H: 2019/07/25 18 UTC: 19.4 S / 65.5 E, VENT MAX= 020 KT, FILLING UP
60H: 2019/07/26 06 UTC: 19.7 S / 63.3 E, VENT MAX= 020 KT, REMNANT LOW
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
T=CI=NIL
FOLLOWED FOR SEVERAL DAYS IN THE AWIO20 FMEE WARNINGS, THE DISTURBED
AREA LOCATED SOUTHWEST OF DIEGO-GARCIA SHOWS QUITE FLUCTUATING
CONVECTION FLUSHING OVER THE LAST 6 HOURS. THE CLOCKWISE CIRCULATION
HAS DIFFICULTY ORGANIZING ITSELF NEAR THE STRONGEST CONVECTION AS
SHOWN BY THE LATEST MICROWAVE IMAGES : THESE DO NOT ALLOW US TO
PRECISELY DEFINE A WELL-ESTABLISHED CENTRE FOR THIS ZONE OF DISTURBED
WEATHER. THE LAST USEFULL ASCAT SWATH (AT 0440UTC) ALLOWS US TO
ESTIMATE WINDS OF AROUND 20/25KT IN THE SOUTHERN SECTOR OF THE
CIRCULATION QUITE FAR FROM THE CENTRE.
WITH A SLIGHTLY EXTENDED VERTICAL CIRCULATION, THE ZONE OF DISTURBED
WEATHER 01 IS SUBJECTED TO A FAIRLY LOW-LEVEL DIRECTIONAL FLOW WHICH
DIRECTS A TRACK GENERALLY TOWARDS THE SOUTH-SOUTHWEST UNDER THE
EFFECT OF A NEAR EQUATORIAL TROUGH. THIS TRACK TEMPORARILY POSITIONS
THE SYSTEM IN A WEAKLY WINDSHEARED ENVIRONMENT, OFFERING IT A SHORT
PERIOD OF INTENSIFICATION OVER THE NEXT 18 HOURS. THEREAFTER, UNDER THE
EFFECT OF A STRONG WIND SHEAR TO FRONT OF A TROUGH CIRCULATING
FURTHER SOUTH, THE SYSTEM WILL FILL UP AND FOLLOW THE TRADE WINDS
TOWARDS THE MASCAREIGNES AT AN EXPIRY DATE OF 2 TO 3 DAYS.
THIS SYSTEM DOES NOT REQUIRE A REGULAR WARNING. NEXT WARNING
TOMORROW AT 06UTC.

[TorSkk]

What agency is MMS? La Reunion is giving this system only a slight chance of developing. Recent scatterometer data indicate it's a tropical cyclone with 35-40 kt winds.

Mauritius Meteorological Services, they name systems west of 55 E

Ah, they're not the RSMC for the SW Indian Ocean. La Reunion is responsible for classifying systems there.

Mauritius is one of two sub-regional tropical cyclone advisory centres in that area (the other one being Madagascar). TCs are named by the Sub-regional Tropical Cyclone Advisory Centre (in this case MMS) after consultation with Meteo-France.