SIO: HALEH - Post-Tropical

[TorSkk]

96S INVEST 190227 1200 5.7S 79.9E SHEM 15 1010

[TorSkk]

Suspect area East of Diego-Garcia :

A wide clockwise circulation is visible on the sat animations between Diego Garcia and the 90th
meridian, but the ASCAT swath did not cover the central area of circulation this morning.
Convection is strong all over this wide area but currently remains ill-organized. OMM buoy nb
1501515 is monitoring a 3-hPa decrease over the last 24 hours. Over the next days, with
strengthening trade winds, a more meridian monsoon flow and a clear improvement in the upper
levels, the environment becomes particularly conducive for cyclogenesis. The wave activity is
probably responsible for these large-scale changes. All models and ensemble available are now in
good agreement to forecast a cyclogenesis followed by a significant gradual intensification next
week.

Over the next 5 days, the risk of development of a moderate tropical storm becomes moderate
Saturday then high from Monday in the East of Diego Garcia.

[TorSkk]

AN AREA OF CONVECTION (INVEST 96S) HAS PERSISTED NEAR 5.7S
79.9E, APPROXIMATELY 442 NM EAST-NORTHEAST OF DIEGO GARCIA. ANIMATED
ENHANCED INFRARED SATELLITE IMAGERY AND AN 271605Z MHS METOP-A 89GHZ
MICROWAVE IMAGE DEPICT A POORLY ORGANIZED LOW LEVEL CIRCULATION
(LLC) WITH CYCLING DEEP CONVECTION. UPPER LEVEL ANALYSIS SHOWS THAT
MODERATE TO STRONG (20-30 KNOT) VERTICAL WIND SHEAR IS OFFSET BY
GOOD DIFFLUENCE ALOFT. A RECENT PARTIAL ASCAT PASS DEPICTS A BROAD
AND ELONGATED CIRCULATION EMBEDDED IN THE MONSOON TROUGH. SEA
SURFACE TEMPERATURES (28-30 CELSIUS) IN THE SURROUNDING WATERS ARE
FAVORABLE FOR FUTURE DEVELOPMENT. GLOBAL MODELS INDICATE THAT THE
SYSTEM WILL TRACK SOUTHWEST AND GRADUALLY STRENGTHEN OVER THE NEXT
48-72 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO
15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1010
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

[TorSkk]

THE AREA OF CONVECTION (INVEST 96S) PREVIOUSLY LOCATED
NEAR 5.7S 79.9E, IS NOW LOCATED NEAR 7.4S 80.0E, APPROXIMATELY 445
NM EAST OF DIEGO GARCIA. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND AN 281544Z MHS METOP-A 89GHZ SHOW A BROAD LOW LEVEL
CIRCULATION (LLC) WITH PERSISTENT BUT DISORGANIZED CONVECTION AND
FRAGMENTED BANDING. UPPER LEVEL ANALYSIS DEPICTS MODERATE TO STRONG
(20-30 KNOT) VERTICAL WIND SHEAR BEING OFFSET BY STRONG OUTFLOW
ALOFT. A RECENT PARTIAL ASCAT PASS DEPICTS BROAD TROUGHING WITH
STRONGER WINDS TO THE SOUTH. SEA SURFACE TEMPERATURES (28-30
CELSIUS) IN THE SURROUNDING WATERS REMAIN FAVORABLE FOR DEVELOPMENT.
DYNAMIC MODELS ARE IN GENERAL AGREEMENT, INDICATING A SOUTHWESTWARD
TRAJECTORY OVER THE NEXT 24-48 HOURS, BUT VARY IN TIME AND INTENSITY
OF DEVELOPMENT, AND SHOW STRONGER WINDS TO THE SOUTH EVENTUALLY
WRAPPING UP IN THE CIRCULATION. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
MEDIUM.

[TorSkk]

Suspect area East of Diego-Garcia :

This area start to present some signs of organization (building deep convection, early signs of
curvature) within a still broad low pressure area. The partial ascat data of this morning locate
approximately a vorticity center near 8°S / 81°E. MSLP is estimated at 1005 hPa according to
nearby buoys. Environmental conditions are already rather supportive for some development. They
are expected to further improve tomorrow with increasing low level cross equatorial inflow likely
due to combined mixed Rossby and equatorial Rossby wave contribution. Therefore within a very
favorable environment, the development of a tropical storm is expected by the week-end. The
expected track brings rapidly the system on a polewards forward motion away from the inhabited
areas.

Over the next 5 days, the risk of development of a moderate tropical storm becomes high from
Saturday South-East of Diego Garcia.

[TorSkk]

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

0.A WARNING NUMBER: 1/10/20182019

1.A TROPICAL DISTURBANCE 10

2.A POSITION 2019/03/01 AT 1200 UTC:
WITHIN 25 NM RADIUS OF POINT 10.3 S / 75.7 E
(TEN DECIMAL THREE DEGREES SOUTH AND
SEVENTY FIVE DECIMAL SEVEN DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 8 KT

3.A DVORAK ANALYSIS: 1.5/1.5/D 0.5/24 H

4.A CENTRAL PRESSURE: 1003 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 25 KT
RADIUS OF MAXIMUM WINDS (RMW): 37 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
NIL

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 600 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS:
12H: 2019/03/02 00 UTC: 11.1 S / 74.5 E, VENT MAX= 030 KT, TROPICAL DEPRESSION
24H: 2019/03/02 12 UTC: 12.4 S / 73.2 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
36H: 2019/03/03 00 UTC: 13.8 S / 72.5 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
48H: 2019/03/03 12 UTC: 14.9 S / 72.3 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
60H: 2019/03/04 00 UTC: 15.9 S / 72.2 E, VENT MAX= 060 KT, SEVERE TROPICAL STORM
72H: 2019/03/04 12 UTC: 16.7 S / 72.1 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/05 12 UTC: 18.5 S / 71.5 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
120H: 2019/03/06 12 UTC: 20.5 S / 70.1 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM

2.C ADDITIONAL INFORMATION:
T=CI=1.5+

FOR 24 HOURS, A VORTICITY SPOT IS BECOMING STRONGER EAST OF
DIEGO-GARCIA. THIS MORNING ASCAT SWATH SHOW THE EXISTENCE OF AN
ELONGATED ASYMMETRIC LOW LEVELS CIRCULATION, ON THE NORTHERN EDGE
OF THE CONVECTIVE ACTIVITY. WINDS ARE REACHING 25KT FAR IN THE POLAR
FEEDING BUT DO NOT EXCEED 15KT IN THE NORTHERN SIDE. LAST MICROWAVE
DATA ESPECIALLY 0845Z AMSR2 CONFIRM THAT THE CORE IS STIL ELONGATED
NORTH OF A BROKEN CONVECTIVE BAND. THIS PATTERN IS PROBABLY THE
CONSEQUENCE OF THE NORTH-EASTERLY VERTICAL WIND SHEAR ANALYSED
AROUND 15/20KT BY CIMSS.

THE SYSTEM IS MOVING ON THE NORTH-WESTERN EDGE OF THE SUBTROPICAL
ANTICYCLONE, PREVENTING AT FIRST A MERIDIONAL TRACK. THE STEERING FLOW
IS THEN EXPECTED TO BEND NORTHWARD AS THE LOW DEEPEN AND THE RIDGE
WEAKEN AT SOUTH. AT LONGER RANGE, THE SYSTEM MAY MOVE
SOUTH-WESTWARD AHEAD OF A NEW SUBTROPICAL RIDGE. THIS SCENARIO IS
BASED ON THE CONSENSUS OF THE MAIN MODELS, TAKING INTO ACCOUNT A SHIFT
AT ANALYSIS.

BOUT ITS INTENSITY, THE DISTURBANCE 10 IS LIKELY TO BENEFIT FROM MORE
CONDUCIVE CONDITIONS THIS WEEK-END. THE SHEAR WILL DECREASE AS THE
LOW MOVES SOUTH AND THE UPPER DIVERGENCE WILL REMAIN VERY GOOD IN
THE WESTERN AND SOUTHERN SEMI-CIRCLE. HOWEVER A NORTH-WESTERLY
CONSTRAINT, TEMPORARILY TOMORROW NIGHT AND FROM MONDAY TO TUESDAY
NIGHT IS LIKELY TO LIMIT THE POTENTIAL OF THE SYSTEM. MOREOVER THE
CURRENT INNER STRUCTURE TO SLOW DOWN THE DEEPENING RATE AT FIRST. THE
TROPICAL CYCLONE STATUS IS THUS NOT CERTAIN.

[TorSkk]

[TorSkk]

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 96S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 9.9S 77.2E TO 15.5S 72.1E
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 20 TO 25 KNOTS. METSAT
IMAGERY AT 010800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 10.2S 76.9E. THE SYSTEM IS MOVING SOUTHWESTWARD AT 06 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 96S) PREVIOUSLY LOCATED
NEAR 7.4S 80.0E, IS NOW LOCATED NEAR 10.2S 76.9E, APPROXIMATELY 315
NM EAST-SOUTHEAST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 010531Z GMI 89GHZ MICROWAVE IMAGE SHOW A SLIGHTLY
ELONGATED LOW LEVEL CIRCULATION WITH PERSISTING CONVECTIVE BANDING
PRESENT TO THE SOUTH AND CONVECTION ALSO PERSISTING OVER THE CENTER.
A 010359Z ASCAT PASS SHOWS A SLIGHTLY ELONGATED CIRCULATION WITH
PRIMARILY 15-20 KNOT WINDS NEAR THE CENTER, BUT 30 KNOT WINDS TO THE
SOUTH BEGINNING TO WRAP IN. THE DISTURBANCE IS CURRENTLY LOCATED IN
AN AREA OF EXCELLENT POLEWARD DIVERGENCE, LOW VERTICAL WIND SHEAR
(10-15 KNOTS), AND WARM SEA SURFACE TEMPERATURES (28-30 KNOTS).
GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL CONTINUE TO
TRACK TO THE SOUTHWEST OVER THE NEXT SEVERAL DAYS AND SHOW
INTENSIFICATION TO WARNING CRITERIA WITHIN THE NEXT 24 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 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
020900Z.//

[TorSkk]

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 4/10/20182019

1.A MODERATE TROPICAL STORM 10 (HALEH)

2.A POSITION 2019/03/02 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 12.2 S / 75.2 E

MOVEMENT: SOUTH 8 KT

3.A DVORAK ANALYSIS: 2.5/2.5/S 0.0/0 H

4.A CENTRAL PRESSURE: 997 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 90 SE: 460 SW: 220 NW: 90
34 KT NE: SE: 220 SW: 190 NW:

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 600 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

T=CI=2.5+

LAST MICRO-WAVES DATA SHOW A CLOSE EYE IN 37RGB, AS THE SYSTEM HAS
INTENSIFY, SO IT WAS NAMED AT 05Z HALEH. THE C-ASCAT DATA OF 0430Z CONFIRM
GALE FORCE WIND IN THE SOUTHERN SEMI-CIRCLE OF THE CIRCULATION.
DEEP CONVECTION HAS STILL A FLUCTUATING NATURE, BUT LAST DATA IN 89 GHZ
OF AMSU AT 0408Z SEEMS TO DEPICT A BEGGING OF CURVATURE PATTERN IN UPPER
LEVEL.

THE SYSTEM IS MOVING ON THE NORTH-WESTERN EDGE OF THE SUBTROPICAL
ANTICYCLONE. THE STEERING FLOW IS THEN EXPECTED TO BEND NORTHWARD AS
THE LOW DEEPEN AND A WEAKNESS DEVELOPS IN THE SUBTROPICAL RIDGE
UNDER THE INFLUENCE OF THE AFOREMENTIONED TROUGH. AT LONGER RANGE,
THE SYSTEM MAY MOVE SOUTH-WESTWARD AHEAD OF A NEW SUBTROPICAL
RIDGE. THIS SCENARIO REMAINS BASED ON THE CONSENSUS OF THE MAIN
RELIABLE MODELS. THERE IS SOME REASONABLE SPREAD AMONGST THE
GUIDANCE WITH VERY GOOD AGREEMENT BETWEEN LATEST OUTPUTS FROM GFS
AND IFS AND UKMO AS AN OUTLIER TO THE EAST.
REGARDS THE INTENSITY FORECAST, THE SYSTEM IS LIKELY TO BENEFIT FROM
IMPROVING ENVIRONMENTAL CONDITIONS TODAY. RI INDEX STILL SUGGEST THAT
A 25 KT INCREASE IS POSSIBLE UP TO 18Z TONIGHT. THE OFFICIAL FORECAST
REMAINS BELOW THAT RATE AT THIS TIME. AFTER THAT TIME, THE RATE OF
INTENSIFICATION IS SLOW DOWN MAINLY DUE TO MID LEVEL SUBTROPICAL DRY
AIR INGESTION WRAPPING FROM THE WESTERN AND NORTHERN CIRCULATION.
SOME SIGNIFICANT OCEANIC CONTAIN MAY OFFSET THIS NEGATIVE
THERMODYNAMICS EFFECTS.

FROM MONDAY AND BEYOND, THE EXPECTED ENVIRONMENTAL CONDITION IN THE
LAST AVAILABLE MODELS REMAINS FAVORABLE IN UPPER LEVELS WITH GOOD
DIVERGENCE AHEAD OF THE TROUGH INVOLVING LESS INFLUENCE FROM THE DRY
MID LEVEL AIR LOCATED JUST NORTH OF THE SYSTEM.

[TyphoonNara]

TPXS10 PGTW 021450

A. TROPICAL CYCLONE 17S (HALEH)

B. 02/1430Z

C. 12.89S

D. 73.86E

E. THREE/MET8

F. T3.0/3.0/D1.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 13A/PBO TIGHTLY CURVED BNDG/ANMTN. CNVCTN WRAPS .60
ON LOG10 SPIRAL YIELDING A DT OF 3.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS:
02/1225Z 12.55S 74.07E SSMS


MILAM

[TyphoonNara]

JTWC is forecasting a 110 knot peak.

[TyphoonNara]

17S HALEH
As of 12:00 UTC Mar 02, 2019:

Location: 12.6°S 74.1°E
Maximum Winds: 45 kt
Minimum Central Pressure: 993 mb

[TorSkk]

Wind shear has to relax first

[TorSkk]

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

0.A WARNING NUMBER: 6/10/20182019

1.A SEVERE TROPICAL STORM 10 (HALEH)

2.A POSITION 2019/03/02 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 13.3 S / 74.0 E
(THIRTEEN DECIMAL THREE DEGREES SOUTH AND
SEVENTY FOUR DECIMAL ZERO DEGREES EAST)
MOVEMENT: SOUTH 8 KT

3.A DVORAK ANALYSIS: 3.0/3.0/D 1.0/24 H

4.A CENTRAL PRESSURE: 992 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 50 KT
RADIUS OF MAXIMUM WINDS (RMW): 65 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 190 SE: 150 SW: 370 NW: 220
34 KT NE: 90 SE: 110 SW: 220 NW: 90
48 KT NE: SE: SW: 90 NW:

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 900 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:

12H: 2019/03/03 06 UTC: 14.4 S / 73.5 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
24H: 2019/03/03 18 UTC: 15.5 S / 73.0 E, VENT MAX= 060 KT, SEVERE TROPICAL STORM
36H: 2019/03/04 06 UTC: 16.4 S / 72.6 E, VENT MAX= 070 KT, TROPICAL CYCLONE
48H: 2019/03/04 18 UTC: 17.3 S / 72.2 E, VENT MAX= 080 KT, TROPICAL CYCLONE
60H: 2019/03/05 06 UTC: 18.2 S / 71.7 E, VENT MAX= 065 KT, TROPICAL CYCLONE
72H: 2019/03/05 18 UTC: 19.2 S / 71.0 E, VENT MAX= 065 KT, TROPICAL CYCLONE

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/06 18 UTC: 22.1 S / 68.3 E, VENT MAX= 080 KT, TROPICAL CYCLONE
120H: 2019/03/07 18 UTC: 24.5 S / 66.2 E, VENT MAX= 065 KT, TROPICAL CYCLONE

2.C ADDITIONAL INFORMATION:

T=CI=3.0+

CONVECTIVE ACTIVITY IS AGAIN RATHER ASYMMETRIC WITH A CENTER ON THE
EASTERN EDGE OF THE COLDEST TOPS (-90C). 89GHZ MICROWAVE IMAGERY
CONFIRM THAT THIS PATTERN IS PROBABLY DUE TO A NORTH-WESTERLY UPPER
CONSTRAINT AND SOME DRY AIR INTRUSION, CURRENTLY HAPPENING. HOWEVER
37GHZ IMAGES, SHOW A CLEAR IMPROVEMENT OF THE INNER CORE ESPECIALLY
ON THE 1756Z GPM. PREVIOUSLY, 1611Z ASCAT AND 1333Z SMAP DATA ALREADY
SUGGESTED THAT STORM WINDS WERE PRESENT IN THE SOUTH-WESTERN
QUADRANT.

THE SYSTEM IS MOVING ON THE NORTH-WESTERN EDGE OF THE SUBTROPICAL
ANTICYCLONE. THE STEERING FLOW IS THEN EXPECTED TO BEND NORTHWARD AS
THE LOW DEEPEN AND A WEAKNESS DEVELOPS IN THE SUBTROPICAL RIDGE. AT
LONGER RANGE, THE SYSTEM MAY MOVE SOUTH-WESTWARD AHEAD OF A NEW
SUBTROPICAL RIDGE. THE CURRENT SCENARIO IS BASED ON A CONSENSUS
BETWEEN THIS MAIN GUIDANCE.

ON THE INTENSITY FORECAST, UP TO TOMORROW MORNING, HALEH WILL
PROBABLY CONTINUE TO UNDERGO THE DETRIMENTAL EFFECTS OF THE
MID-TROPOSPHERE ENVIRONMENT. DEEPENING IS EXPECTED TO SLOW DOWN OR
EVEN STOP. SUNDAY EVENING AND ON MONDAY, HALEH IS FORECAST TO UNDERGO
A NEW DEEPENING PHASE WITH THE EXPECTED DECREASE OF THE
NORTH-WESTERLY CONSTRAINT. ON TUESDAY, UPPER ENVIRONMENT MAY AGAIN
DETERIORATE TEMPORARILY. AT LONGER RANGE, DESPITE A DECAY OF THE UPPER
DIVERGENCE, HALEH SHOULD HAVE A SECOND DEEPENING PHASE, ONLY LIMITED
BY THE GRADUALLY DECAYING OCEANIC POTENTIAL.

[TorSkk]

TROPICAL CYCLONE (TC) 17S (HALEH), LOCATED APPROXIMATELY 377 NM
SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTH-SOUTHWESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS A FAST-CONSOLIDATING SYSTEM WITH EXPANSIVE
RAIN BANDS WRAPPING IN MOSTLY FROM THE EQUATORWARD SIDE. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE WELL-DEFINED
MICROWAVE EYE FEATURE IN THE 021756Z GPM NEAR-SURFACE 36GHZ COLORIZED
IMAGE. THE INITIAL INTENSITY IS BASED ON THE DVORAK ESTIMATE OF
T3.5/55KTS FROM PGTW. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH
EXCELLENT RADIAL OUTFLOW, LOW (10-15KT) VERTICAL WIND SHEAR (VWS),
AND WARM (30C) SEA SURFACE TEMPERATURES (SSTS). TC 17S WILL CONTINUE
ON ITS CURRENT TRACK ALONG THE NORTHWEST PERIPHERY OF A SUBTROPICAL
RIDGE TO THE SOUTHEAST. AFTER TAU 48, THE STR WILL BUILD WESTWARD AND
DRIVE THE CYCLONE ON A MORE SOUTHWESTWARD TRAJECTORY. THE FAVORABLE
CONDITIONS MENTIONED ABOVE WILL FUEL RAPID INTENSIFICATION UP TO
115KTS BY TAU 72. AFTERWARD, INCREASING VWS AND COOLING SSTS WILL
PROMOTE A STEADY WEAKENING AND, BY TAU 120, TC HALEH WILL BE DOWN TO
90KTS. THE NUMERICAL MODELS HAVE COME INTO BETTER AGREEMENT WITH
MINIMAL SPREADING UP TO 245NM BY TAU 120, LENDING HIGH CONFIDENCE TO
THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 021800Z
IS 20 FEET.

[TyphoonNara]

Now a cat 1 cyclone, SATCON agrees.

17S HALEH
As of 06:00 UTC Mar 03, 2019:

Location: 14.6°S 73.6°E
Maximum Winds: 65 kt
Minimum Central Pressure: 984 mb

CURRENT ESTIMATE
Date (mmddhhmm): 03022323
SATCON: MSLP = 982 hPa MSW = 66 knots
SATCON Member Consensus: 66.0 knots
Pressure -> Wind Using SATCON MSLP: 68 knots
Distance to Outer Closed Isobar Used is 195 nm
Eye Size Correction Used is 0 knots Source: NA

[TyphoonNara]

TPXS10 PGTW 030556

A. TROPICAL CYCLONE 17S (HALEH)

B. 03/0530Z

C. 14.62S

D. 73.55E

E. FIVE/MET8

F. T4.0/4.0/D1.5/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. CNVCTN WRAPS 1.05 ON LOG10
SPIRAL YIELDING A DT OF 4.0. THE MET AGREES AND THE PT YIELDS A
3.5. DBO DT.

I. ADDITIONAL POSITIONS:
03/0119Z 14.05S 73.55E SSMS


MILAM

[TorSkk]

12Z warning graphic from MFR

[TorSkk]

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

0.A WARNING NUMBER: 9/10/20182019

1.A SEVERE TROPICAL STORM 10 (HALEH)

2.A POSITION 2019/03/03 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 15.5 S / 73.6 E
(FIFTEEN DECIMAL FIVE DEGREES SOUTH AND
SEVENTY THREE DECIMAL SIX DEGREES EAST)
MOVEMENT: SOUTH 8 KT

3.A DVORAK ANALYSIS: 4.0/4.0/D 0.5/12 H

4.A CENTRAL PRESSURE: 982 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 60 KT
RADIUS OF MAXIMUM WINDS (RMW): 65 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 240 SE: 370 SW: 430 NW: 170
34 KT NE: 150 SE: 260 SW: 260 NW: 130
48 KT NE: 80 SE: 80 SW: 80 NW: 60

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 900 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2019/03/04 00 UTC: 16.6 S / 73.4 E, VENT MAX= 070 KT, TROPICAL CYCLONE
24H: 2019/03/04 12 UTC: 17.6 S / 73.0 E, VENT MAX= 080 KT, TROPICAL CYCLONE
36H: 2019/03/05 00 UTC: 18.5 S / 72.5 E, VENT MAX= 085 KT, TROPICAL CYCLONE
48H: 2019/03/05 12 UTC: 19.5 S / 72.0 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE
60H: 2019/03/06 00 UTC: 20.5 S / 70.9 E, VENT MAX= 095 KT, INTENSE TROPICAL
CYCLONE
72H: 2019/03/06 12 UTC: 21.7 S / 69.8 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/07 12 UTC: 24.3 S / 67.7 E, VENT MAX= 065 KT, TROPICAL CYCLONE
120H: 2019/03/08 12 UTC: 27.5 S / 65.4 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM

2.C ADDITIONAL INFORMATION:

T=CI=4.0+

DURING THE LAST 6 HOURS, CLOUD PATTERN HAS IMPROVED. SOME BURSTS OF
CONVECTION HAVE OCCURRED NEAR THE CENTER WITHIN THE EASTERN
QUADRANT RE-HUMIDIFYING PROGRESSIVELY THIS QUADRANT INVADED BY DRY
AIR. SO, A RAGGED WARM POINT HAS APPEARED IN INFRARED IMAGERY.
ACCORDING WITH THE CONVENTIONAL IMAGERY, THE 1032Z 85GHZ SSMI SWATH
SHOW A CONSOLIDATING EYE FEATURE.

TODAY, THE STEERING FLOW IS EXPECTED TO BEND NORTHWARD AS A WEAKNESS
DEVELOPS IN THE SUBTROPICAL RIDGE. AT LONGER RANGE, THE SYSTEM MAY
MOVE SOUTH-WESTWARD AHEAD OF A NEW SUBTROPICAL RIDGE. THE CURRENT
SCENARIO IS BASED ON A CONSENSUS BETWEEN THIS MAIN GUIDANCE.
THE SYSTEM SHOULD EXPERIENCE FAVORABLE ENVIRONMENTAL CONDITIONS TO
KEEP ON ITS STRENGTHENING DURING THE NEXT FEW DAYS. THE VERTICAL
WINDSHEAR IS FORECASTED TO REMAIN WEAK AHEAD AN UPPER LEVEL TROUGH
THAT PROVIDES A GOOD UPPER LEVEL DIVERGENCE. THE INTENSITY FORECAST IS
IN A GOOD AGREEMENT WITH THE ICNW CONSENSUS. FROM WEDNESDAY, THE
UPPER LEVEL DIVERGENCE SHOULD DECREASE AND A MODERATE NORTHWESTERN
VERTICAL WINDSHEAR SHOULD ESTABLISH. SO THE INTENSITY SHOULD BEGIN TO
DECREASE BUT LIMITED BY A GOOD OCEANIC HEAT CONTENT (OHC). FROM FRIDAY,
THE WEAKENING SHOULD BECOME MORE SIGNIFICANTLY WITH AN INCREASING
VERTICAL WINDSHEAR AND AN INSUFFICIENT OHC.

[TyphoonNara]

17S HALEH
As of 00:00 UTC Mar 04, 2019:

Location: 17.1°S 73.3°E
Maximum Winds: 90 kt
Minimum Central Pressure: 956 mb