SIO: ALVARO - Post-Tropical

[Subtrop]

95S INVEST 231229 0600 19.8S 35.3E SHEM 15 1008

[Subtrop]

WTIO30 FMEE 310640
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 6/1/20232024
1.A TROPICAL DEPRESSION 1

2.A POSITION 2023/12/31 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 20.3 S / 38.3 E
(TWENTY DECIMAL THREE DEGREES SOUTH AND
THIRTY EIGHT DECIMAL THREE DEGREES EAST)
MOVEMENT: SOUTH-EAST 5 KT

3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/6 H

4.A CENTRAL PRESSURE: 1000 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 110 SE: 120 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 600 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2023/12/31 18 UTC: 21.0 S / 39.9 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 155 SE: 185 SW: 0 NW: 100
34 KT NE: 75 SE: 130 SW: 0 NW: 75

24H: 2024/01/01 06 UTC: 21.5 S / 41.6 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 175 SE: 215 SW: 110 NW: 110
34 KT NE: 95 SE: 150 SW: 0 NW: 85

36H: 2024/01/01 18 UTC: 21.6 S / 43.9 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 195 SE: 230 SW: 120 NW: 110
34 KT NE: 100 SE: 165 SW: 0 NW: 85

48H: 2024/01/02 06 UTC: 21.3 S / 45.9 E, VENT MAX= 025 KT, OVERLAND
DEPRESSION

60H: 2024/01/02 18 UTC: 21.6 S / 48.5 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 230 SE: 270 SW: 130 NW: 130
34 KT NE: 130 SE: 195 SW: 75 NW: 95

72H: 2024/01/03 06 UTC: 22.2 S / 50.0 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM

2.B LONGER-RANGE OUTLOOK:
NIL


2.C ADDITIONAL INFORMATION:
T=CI=2.5

OVER THE LAST 6 HOURS, THE CONVECTION HAS CLEARLY IMPROVED, IN THE
EASTERN SEMICIRCLE, SHOWING SIGNS OF CURVATURE SUGGESTING AN
INTENSIFICATION. THIS IS ALSO CONFIRMED BY SSMIS-F17'S MICROWAVE PASS
FROM 0348Z, SHOWING A HOOK SHAPE ON THE 89GHZ COLOR IMAGE, MOVING
UPWARDS IN THE EASTERN SEMICIRCLE. THE POOR QUALITY OF THE 37GHZ
MICROWAVE DOES NOT CLEARLY SHOW A RING AT PRESENT, SUGGESTING THAT
THE SYSTEM IS STILL BEYOND THE TROPICAL STORM STAGE. THUS, GIVEN
THESE ELEMENTS AND DVORAK'S SUBJECTIVE STUDY, THE SYSTEM SEEMS TO
HAVE REACHED THE TROPICAL DEPRESSION STAGE.

THE SYSTEM CONTINUES TO CROSS THE MOZAMBIQUE CHANNEL, UNDER THE
INFLUENCE OF A WEST-NORTH-WEST FLOW DRIVEN BY A RIDGE OF HIGH
PRESSURE NEAR THE EQUATOR TO THE NORTH. ITS TRAJECTORY WILL THEREFORE
BE TOWARDS THE WEST COAST OF MADAGASCAR, WHICH IT COULD REACH LATE ON
MONDAY OR DURING THE NIGHT FROM MONDAY TO TUESDAY. THE DISPERSION OF
NUMERICAL WEATHER FORECASTS REMAINS QUITE SIGNIFICANT FOR ITS SPEED
OF MOVEMENT, WITH A BIG DIFFERENCE BETWEEN GFS AND THE OTHER MODELS.
THE TRACK FORECAST BY RSMC IS CLOSE TO THE LATEST IFS AND AROME RUNS
IN TERMS OF TIMING.THE AMERICAN GFS MODEL IS STILL TOO FAST, BOTH FOR
LANDING AND FOR EXITING THE SOUTH-WEST INDIAN OCEAN BASIN. HOWEVER,
WHEN IT COMES TO EXITING THE EASTERN COAST OF MADAGASCAR, EUROPEAN
GUIDANCES ARE NOW IN AGREEMENT WITH THE AMERICAN MODEL ON THIS
POSSIBILITY.THE RSMC ANALYSIS THEREFORE TAKES THIS SCENARIO INTO
ACCOUNT, EVEN IF THERE IS STILL A WIDE DISPERSION IN TERMS OF TIMING,
AT THE BEGINNING OF NEXT WEEK.

IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR
SHORT-TERM DEVELOPMENT, WITH FAIRLY GOOD LOW-LEVEL CONVERGENCE,
STRONG OCEANIC POTENTIAL AND GOOD POLAR HIGH-LEVEL DIVERGENCE.
HOWEVER, THESE CONDITIONS ARE OFFSET BY MODERATE WEST-SOUTH-WEST
SHEAR IN THE MID-TROPSPHERE. THIS MID-LEVEL SHEAR SHOULD GRADUALLY
STRENGTHEN, BRINGING DRY AIR TO THE MID-TROPOSPHERE. FROM MONDAY
EVENING ONWARDS, DEEP SHEAR IS SET TO BE ADDED. THIS INFLUX OF DRY
AIR COULD SLOW THE SYSTEM'S DEVELOPMENT UNTIL LANDING. THE CURRENT
FORECAST THEREFORE SUGGESTS AN INTENSIFICATION THROUGH SUNDAY NIGHT
INTO MONDAY, FOLLOWED BY A LEVELLING OFF IN INTENSITY DUE TO THE
EFFECTS OF THE SHEAR. THE SYSTEM COULD PROBABLY REACH THE STAGE OF A
MODERATE TROPICAL STORM TODAY, OR EVEN OVER THE COURSE OF THE NEXT
EVENING. AFTER WEAKENING OVER MADAGASCAR, THE SYSTEM COULD
TEMPORARILY STRENGTHEN OVER THE WARM WATERS OF THE INDIAN OCEAN TO
TROPICAL STORM STRENGTH, BEFORE WEAKENING PERMANENTLY UNDER THE
EFFECT OF PERSISTENT NORTH-WESTERLY SHEAR.

IMPACTS ON INHABITED LAND :
MADAGASCAR (TOLIARA PROVINCE, FIANARANTSOA PROVINCE):
- GALE-FORCE WINDS LIKELY TO ARRIVE (20-40%) FROM MIDDAY MONDAY UNTIL
NIGHT MONDAY TO TUESDAY.
- HEAVY RAIN FROM MONDAY ON THE WEST COAST, SPREADING TO THE EAST
COAST ON TUESDAY.RAINFALL TOTALS OF 100-200MM, LOCALLY 300M.
- WAVES CLOSE TO 4M NEAR THE IMPACT ZONE AROUND MONDAY EVENING.=

[Subtrop]

WTXS21 PGTW 310730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 95S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 20.2S 38.2E TO 21.8S 44.0E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 310700Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 20.4S 38.5E. THE SYSTEM IS MOVING EAST-SOUTHEASTWARD AT 06
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 95S) PREVIOUSLY LOCATED NEAR
19.8S 37.6E IS NOW LOCATED NEAR 20.4S 38.5E, APPROXIMATELY 158 NM
NORTHWEST OF EUROPA ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER WITH FLARING DEEP
CONVECTION BEGINNING TO BUILD OVER THE CENTER. A 310344Z SSMIS 91 GHZ
MICROWAVE IMAGE SHOWS CONVECTIVE BANDING WRAPPING AROUND THE EASTERN
SEMI-CIRCLE AND PORTIONS OF THE WESTERN SEMI-CIRCLE. ENVIRONMENTAL
ANALYSIS INDICATES THAT 95S IS IN A FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH ROBUST OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND
SHEAR, AND WARM (28-29 C) SEA SURFACE TEMPERATURES. HOWEVER, AT AROUND
TAU 24, ENVIRONMENTAL CONDITIONS BEGIN TO BECOME LESS FAVORABLE AS DRY
AIR IS INTRODUCED TO THE SYSTEM FROM THE WEST. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT 95S WILL TRACK EAST-SOUTHEASTWARD TOWARD MADAGASCAR AND
CONTINUE TO DEVELOP OVER THE NEXT 24-48 HOURS. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
010730Z.//
NNNN

[Subtrop]

The basin has a near-equatorial talweg configuration (NET), located at 05oS between 60o and 75oE. The convective activity present to the north of this NET remains fairly fragmented. The rest of the convective convective activity is centered around the moderate tropical storm ALVARO located in the Mozambique Channel.

Moderate Tropicae Storm ALVARO :

Location at 09UTC : 20.4S / 38.5E

Max average winds (10min) : 35 kt

Central pressure : 997 hPa

Movement : East-south-east, 5 kt

For more information, please refer to warnings WTIO30 and WTIO24 at 12UTC and following.

[Sciencerocks]

 https://twitter.com/cyclonicwx/status/1741490231084208501

[cycloneye]

Just in time to be part of the 2023 list of cyclones.

[al78]

I never cease to be amazed at the frequency of active tropical cyclones on New Years Eve, and this after weeks of crickets.

The issue for me comes down to the TSR web site. To track storms it needs to give each storm a unique ID which remains unchanged through the storm's lifetime. The storm ID consists of the current year, the storm number and a letter corresponding to the basin. When a storm spans a calendar year, the current year changes so the TSR code will treat it as a new storm resulting in a duplicate of the storm with one track segment corresponding to the year 2023 and the other segment corresponding to 2024. I have to put a temporary hack into the code to stop this happening and I was hoping to get away with not having to do it this year, but of course not!

[Hurricane2022]

[DioBrando]

Happy new year Alvaro (UTC)

[cycloneye]

Bulletin of January 1 at 4:06 p.m. local time in Reunion Island (3:06 p.m. local time in Mayotte):

STRONG TROPICAL STORM ALVARO

Maximum winds (averaged over 10 minutes) estimated at sea: 110 km/h.

Maximum gusts estimated at sea: 155 km/h.

Estimated pressure at center: 985 hPa.

Position on January 1 at 4 p.m. local time Meeting: 21.5 South / 42.9 East.

Distance from the Reunion coast: 1280 km to the WEST sector

Distance from Mayotte: 990 km to the SOUTH-SOUTH-WEST sector

Travel: EST, 15 km/h.

System information:

- Alvaro remains at the stage of a strong tropical storm for the moment. Its landing on the west coast of Madagascar is scheduled for late afternoon (around 15 UTC) in the province of Toliara (near Cape Saint-Vincent).

- Strong and even locally destructive winds are expected on Monday from midday until the beginning of the night. With the progression of the system inland, these winds will ease on Tuesday before the system is likely to emerge from the east coast on Wednesday.

- Intense rains linked to the system are expected first in the province of Toliara on Monday, then in the province of Fianarantsoa between Tuesday and Wednesday. Earlier rains (from Monday evening) are also expected in the province of Fianarantsoa linked to the convergence of flows upstream of the tropical system.

- Residents of the areas concerned are therefore invited to follow the evolution of the forecasts.

- After exiting the east coast of Madagascar on Wednesday, this system should not threaten other lands and should circulate a good distance from the Mascarenes while gradually attenuating from Thursday.

Here are the forecast intensities and positions of this low pressure system over the next few days:

DEPRESSION ON EARTH,

Center positioned on 02/01 at 4 p.m. local, at 21.4 South / 46.3 East.

MODERATE TROPICAL STORM,

Center positioned on 03/01 at 4 p.m. local, at 22.7 South / 50.3 East.

POST-TROPICAL DEPRESSION,

Center positioned on 04/01 at 4 p.m. local, at 24.2 South / 54.1 East.

RESIDUAL DEPRESSION,

Center positioned on 05/01 at 4 p.m. local, at 25.6 South / 58.1 East.

[Hurricane2022]

Landfall.

[Hurricane2022]

It may have briefly attained hurricane status.
 https://twitter.com/Sausius_wx/status/1741853127932866738



 https://twitter.com/zeb199818/status/1741747327147356584

[cycloneye]

STRONG TROPICAL STORM ALVARO

Maximum winds (averaged over 10 minutes) estimated at sea: 95 km/h.

Maximum gusts estimated at sea: 130 km/h.

Estimated pressure at center: 989 hPa.

Position on January 1 at 10 p.m. local Meeting: 21.4 South / 43.9 East.

Distance from the Reunion coast: 1180 km to the WEST sector

Distance from Mayotte: 960 km to the SOUTH sector

Travel: EST, at 17 km/h.

System information:

- Alvaro landed as a strong tropical storm, in the province of Tuléar, not far from the town of Morombe around 16 UTC.

- Strong and locally destructive winds are underway in the province of Tuléar, until the middle of next night, before gradually diminishing with the movement of the phenomenon towards the East. In fact, strong winds may occasionally blow over the province of Fianarantsoa tomorrow, Tuesday, then a probable exit of the system via the east coast is expected by Wednesday.

- Intense rains are also underway in the province of Tuléar until Tuesday, then in the province of Fianarantsoa between Tuesday and Wednesday.

- Residents of the areas concerned are therefore invited to follow the evolution of the forecasts.

- After exiting the east coast of Madagascar on Wednesday, this system should not threaten other lands and should circulate a good distance south of the Mascarenes while gradually weakening from Thursday, sinking towards the latitudes southern.

Here are the forecast intensities and positions of this low pressure system over the next few days:

DEPRESSION ON EARTH,

Center positioned on 02/01 at 10 p.m. local, at 21.6 South / 47.7 East.

MODERATE TROPICAL STORM,

Center positioned on 03/01 at 10 p.m. local, at 23.1 South / 51.0 East.

DEPRESSION FILLING,

Center positioned on 04/01 at 10 p.m. local, at 25.2 South / 54.7 East.

[cycloneye]

Bulletin of January 2 at 10:40 a.m. local time in Reunion (9:40 a.m. local time in Mayotte):


DEPRESSION ON EARTH number 1

(ALVARO)

Maximum winds (averaged over 10 minutes) estimated at sea: 45 km/h.

Maximum gusts estimated at sea: 65 km/h.

Estimated pressure at center: 1003 hPa.

Position on January 2 at 10 a.m. local: 21.5 South / 46.0 East.

Distance from the Reunion coast: 955 km to sector: WEST

Distance from Mayotte: 970 km to sector: SOUTH

Travel: EST, at 19 km/h.

System information:

- Alvaro evolved on Madagascar last night and weakened. It continues to move eastwards and should emerge out to sea this evening south of Mananjary.

- Strong winds could occasionally blow strongly in the province of Fianarantsoa today and especially next night on the coast with gusts reaching 100km/h. Intense rains are also expected in this province until late next night.

- After emerging at sea, this system should no longer directly threaten inhabited lands and should circulate a good distance towards the south, south of the Mascarenes while gradually losing its tropical characteristics from Thursday.

Here are the forecast intensities and positions of this low pressure system over the coming days:

MODERATE TROPICAL STORM,

Center positioned on 03/01 at 10 a.m. local, at 22.7 South / 50.0 East.

POST-TROPICAL DEPRESSION,

Center positioned on 04/01 at 10 a.m. local, at 25.6 South / 53.6 East.

EXTRATROPICAL DEPRESSION,

Center positioned on 05/01 at 10 a.m. local, at 28.1 South / 57.1 East.

[Subtrop]

WTIO30 FMEE 030642
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 18/1/20232024
1.A MODERATE TROPICAL STORM 1 (ALVARO)

2.A POSITION 2024/01/03 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 23.3 S / 50.7 E
(TWENTY THREE DECIMAL THREE DEGREES SOUTH AND
FIFTY DECIMAL SEVEN DEGREES EAST)
MOVEMENT: SOUTH-WEST 14 KT

3.A DVORAK ANALYSIS: 3.0/3.5/W 0.5/6 H

4.A CENTRAL PRESSURE: 990 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT
RADIUS OF MAXIMUM WINDS (RMW): 65 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 185 SE: 185 SW: 110 NW: 110
34 KT NE: 150 SE: 150 SW: 65 NW: 65
48 KT NE: 0 SE: 0 SW: 0 NW: 0
64 KT NE: 0 SE: 0 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 600 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2024/01/03 18 UTC: 25.1 S / 53.1 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 215 SE: 260 SW: 175 NW: 150
34 KT NE: 155 SE: 175 SW: 130 NW: 120

24H: 2024/01/04 06 UTC: 26.4 S / 55.2 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 240 SE: 280 SW: 195 NW: 155
34 KT NE: 165 SE: 195 SW: 130 NW: 120

36H: 2024/01/04 18 UTC: 27.6 S / 58.7 E, VENT MAX= 030 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 260 SE: 305 SW: 205 NW: 165

48H: 2024/01/05 06 UTC: 28.4 S / 62.0 E, VENT MAX= 030 KT,
EXTRATROPICAL DEPRESSION
28 KT NE: 285 SE: 325 SW: 215 NW: 185

60H: 2024/01/05 18 UTC: 28.9 S / 64.7 E, VENT MAX= 030 KT,
EXTRATROPICAL DEPRESSION
28 KT NE: 285 SE: 325 SW: 215 NW: 185


2.B LONGER-RANGE OUTLOOK:
NIL


2.C ADDITIONAL INFORMATION:
BASED ON THE LATEST GCOM MICROWAVE IMAGES FROM 2206Z AND SSMIS FROM
0028Z, 0219Z AND 0308Z, ALVARO'S BESTRACK HAS BEEN REVISED A LITTLE
FURTHER SOUTH THAN PREVIOUSLY, WITH A SLIGHTLY EARLIER OUTFLOW TO SEA
EAST OF MADAGASCAR. OVER THE LAST 6 HOURS, CONVECTION HAS WEAKENED
SIGNIFICANTLY AND THE SYSTEM HAS ENCOUNTERED A 25KT WESTERLY SHEAR
THAT HAS EXPOSED ITS CENTER (VISIBLE IN THE IMAGE). IN ACCORDANCE
WITH THE OBJECTIVE AND SUBJECTIVE DATA AVAILABLE, THE SYSTEM IS
MAINTAINED AS A MODERATE TROPICAL STORM WITH MAXIMUM WINDS OF 45KT.

IN TERMS OF TRACK, THE PHILOSOPHY OF MOVING SOUTH-EASTWARDS UNDER THE
INFLUENCE OF THE RIDGE OF HIGH PRESSURE STRENGTHENING OVER THE
NORTHERN MASCARENE ISLANDS REMAINS UNCHANGED. HOWEVER, TO TAKE INTO
ACCOUNT THE POSITION OBSERVED FURTHER SOUTH AND THE LATEST AVAILABLE
MODELS, THE TRACK HAS BEEN SLIGHTLY SHIFTED FURTHER SOUTH AND
SLIGHTLY ACCELERATED.

OVER THE NEXT FEW HOURS, ALVARO WILL GRADUALLY ENCOUNTER LESS
FAVORABLE ENVIRONMENTAL CONDITIONS, WITH STRONG WESTERLY SHEAR
ALLOWING DRY AIR TO INTRUDE. THE MODERATE TROPICAL STORM STAGE SHOULD
BE MAINTAINED FOR A MAXIMUM OF 12 HOURS BEFORE THE SYSTEM BEGINS ITS
EXTRA-TROPICALIZATION PHASE AND LOSES ITS TROPICAL CHARACTERISTICS
WITHIN 48 HOURS.

THE SYSTEM NO LONGER POSES A THREAT TO INHABITED LAND.=