SIO: IDAI - Post-Tropical

[cycloneye]

 https://twitter.com/AlexLubbers2/status/1104497218810048512

[euro6208]

Models are very robust on this one.

[doomhaMwx]

Very bad for Mozambique if those forecasts of a cat 3+ cyclone coming ashore verifies.
A quick search shows that the last cat 4 cyclone to make landfall over Mozambique was Leon-Eline in 2000.

[TyphoonNara]

JTWC is forecasting a 110 knot peak.

[TyphoonNara]

TPXS11 PGTW 100009

A. TROPICAL CYCLONE 18S (W OF MADAGASCAR)

B. 09/2345Z

C. 17.20S

D. 42.42E

E. FIVE/MET8

F. T2.5/2.5/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 38A/PBO SBC/ANMTN. .40 WRAP ON LOG10 SPIRAL YIELDS
A 2.5 DT. MET AND PT YIELD A 2.5. DBO DT.

I. ADDITIONAL POSITIONS:
09/1847Z 16.83S 42.35E MMHS
09/2155Z 17.02S 42.38E ATMS


BERMEA

[TyphoonNara]

100300Z POSITION NEAR 17.2S 42.5E.
TROPICAL CYCLONE 18S (IDAI), LOCATED APPROXIMATELY 325 NM NORTH-
NORTHEAST OF EUROPA ISLAND, HAS TRACKED SOUTHEASTWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH FORMATIVE DEEP
CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION
CENTER (LLCC). A 092244Z AMSU 183GHZ MICROWAVE IMAGE SHOWS
CONVECTIVE BANDING WRAPPING TIGHTLY INTO A WELL-DEFINED LLCC, WHICH
SUPPORTS THE INITIAL POSITION WITH FAIR CONFIDENCE. THE INITIAL
INTENSITY IS ASSESSED AT 40 KNOTS BASED ON DVORAK CURRENT INTENSITY
ESTIMATES OF T2.5-3.0 (35-45 KNOTS) FROM KNES, PGTW, AND FMEE AS
WELL AS A 100115Z AUTOMATED DVORAK TECHNIQUE ESTIMATE OF 43 KNOTS.
UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH GOOD
EQUATORWARD AND POLEWARD OUTFLOW, ENHANCED BY A JET TO THE SOUTHEAST
OVER SOUTHERN MADAGASCAR, AS WELL AS LOW VERTICAL WIND SHEAR AND
WARM SST (28-30 CELSIUS). TC 18S IS CURRENTLY TRACKING SOUTHEASTWARD
UNDER THE STEERING INFLUENCE OF THE NEAR-EQUATORIAL RIDGE TO THE
NORTH BUT IS BEGINNING ITS RECURVE AND WILL COMPLETE ITS TURN TO
SOUTHWESTWARD BY TAU 24 AS A SUBTROPICAL RIDGE (STR) BUILDS IN FROM
THE SOUTHWEST. AFTER TAU 24, THE STR WILL BECOME THE PRIMARY
STEERING INFLUENCE AND TC 18S WILL ACCELERATE SOUTHWESTWARD TOWARD
MOZAMBIQUE, MAKING LANDFALL AFTER TAU 96. THE JTWC FORECAST TRACK
HAS BEEN ADJUSTED FURTHER SOUTH AFTER TAU 24 AS THE MULTI-MODEL
CONSENSUS CONTINUES TO SHOW A MORE GRADUAL RECURVE BEFORE HEADING
BACK WESTWARD. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT ABOUT
THE RECURVE, WITH PRIMARILY NORTH-SOUTH SPREAD BEFORE TAU 72. AFTER
TAU 72, SIGNIFICANT DIFFERENCES IN PREDICTED TRACK SPEED ARISE AS TC
18S APPROACHES MOZAMBIQUE AND MAKES LANDFALL. OVERALL, THERE IS LOW
CONFIDENCE (HIGH UNCERTAINTY) IN THE JTWC FORECAST TRACK. TC 18S IS
FORECAST TO INTENSIFY STEADILY DUE TO FAVORABLE CONDITIONS AND WILL
REACH A PEAK INTENSITY OF 110 KNOTS BY TAU 96. AFTER LANDFALL, THE
SYSTEM WILL WEAKEN RAPIDLY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
100000Z IS 18 FEET. NEXT WARNINGS AT 100900Z, 101500Z, 102100Z AND
110300Z.//

[TorSkk]

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

0.A WARNING NUMBER: 8/11/20182019

1.A MODERATE TROPICAL STORM 11 (IDAI)

2.A POSITION 2019/03/10 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 17.4 S / 42.8 E
(SEVENTEEN DECIMAL FOUR DEGREES SOUTH AND
FORTY TWO DECIMAL EIGHT DEGREES EAST)
MOVEMENT: QUASI-STATIONARY.

3.A DVORAK ANALYSIS: 3.5/3.5/D 0.5/12 H

4.A CENTRAL PRESSURE: 987 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT
RADIUS OF MAXIMUM WINDS (RMW): 37 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 190 SE: 190 SW: 200 NW: 170
34 KT NE: 100 SE: 100 SW: 140 NW: 100

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 400 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS:
12H: 2019/03/11 00 UTC: 17.5 S / 42.7 E, VENT MAX= 065 KT, TROPICAL CYCLONE
24H: 2019/03/11 12 UTC: 17.7 S / 42.4 E, VENT MAX= 080 KT, TROPICAL CYCLONE
36H: 2019/03/12 00 UTC: 18.1 S / 41.6 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE
48H: 2019/03/12 12 UTC: 18.7 S / 40.9 E, VENT MAX= 095 KT, INTENSE TROPICAL
CYCLONE
60H: 2019/03/13 00 UTC: 19.0 S / 39.9 E, VENT MAX= 095 KT, INTENSE TROPICAL
CYCLONE
72H: 2019/03/13 12 UTC: 19.3 S / 38.6 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/14 12 UTC: 19.4 S / 35.7 E, VENT MAX= 075 KT, TROPICAL CYCLONE
120H: 2019/03/15 12 UTC: 18.9 S / 33.3 E, VENT MAX= 030 KT, OVERLAND DEPRESSION

2.C ADDITIONAL INFORMATION:
T=CI=3.5-

THE CURVED BAND PATTERN IS MAINTAINED BUT SHOWS A STRONG FLUCTUATION
IN CONVECTION. SO, A WELL-MARKED CONVECTIVE CLUSTER WAS TRIGGERED IN
THE LAST HOUR EAST OF THE CENTER. A DVORAK ANALYSIS OF 3.5- CAN BE DONE,
LEAVING IDAI AT THE UPPER LIMIT OF THE MODERATE TROPICAL STORM
THRESHOLD, WITH ESTIMATED WINDS IN THE ORDER OF 45KT. AT 12UTC, IDAI'S
ESTIMATED CENTRE IS LOCATED AT 30KM SOUTH OF NOVA JUAN ISLAND.
WITH THE WEAKENING OF THE NEAR-EQUATORIAL RIDGE AND THE
STRENGTHENING OF THE SUBTROPICAL RIDGE, THE MODERATE TROPICAL STORM
IDAI REMAINS IN CONDITIONS OF ALMOST NO GUIDING FLOW. IT IS NECESSARY TO
WAIT ALMOST 24 HOURS FOR THE SYSTEM TO RESUME A BETTER DEFINED TRACK
TOWARDS THE WEST-SOUTHWEST. AT THE END OF MONDAY, THE SYSTEM SHOULD
ACCELERATE WESTSOUTHWESTWARD STEERING BY THE SUBTROPICAL RIDGE. THE
SYSTEM IS EXPECTED TO LAND OVER MOZAMBIQUE COASTLINES THURSDAY.
MODELS ARE IN GOOD AGREEMENT WITH THIS TRACK PHILOSOPHY BUT THERE IS
UNCERTAINTY ABOUT THE TIMING AND DISPERSION FURTHER SOUTH AT THE
LANDFALL AREA.

ON THIS TRACK, ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR
INTENSIFICATION WITH AN INTENSIFICATION RATE ALLOWING IT TO REACH THE
TROPICAL CYCLONE THRESHOLD WITHIN 24 HOURS. THE SYSTEM, SHOULD EVOLVE
BENEATH THE UPPER LEVEL RIDGE WITH A WEAK VERTICAL WINDSHEAR AND A
GOOD POLERWARD DIVERGENCE. OCEAN HEAT CONTENT IS VERY GOOD. THE
PERIOD OF LIMITED DISPLACEMENT OVER THE NEXT 24 HOURS WILL HOWEVER
CONSUME THE OCEAN'S ENERGY POTENTIAL AND WILL TEMPORARILY LIMIT THE
INTENSIFICATION BEFORE THE RESUMPTION OF THE IDAI'S DISPLACEMENT. IN
THESE CONDITIONS, THE LIKELIHOOD THAT A MATURE SYSTEM WITH A HIGH
INTENSITY LANDS OVER MOZAMBIQUE IS VERY HIGH.

[TorSkk]

[wxman57]

Nice open eye on this "50 mph TS" (according to the official SW Indian Ocean RSMC in La Reunion).

[cycloneye]

 https://twitter.com/CIMSS_Satellite/status/1104811852117217282

[TorSkk]

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

0.A WARNING NUMBER: 9/11/20182019

1.A TROPICAL CYCLONE 11 (IDAI)

2.A POSITION 2019/03/10 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 17.2 S / 43.2 E

MOVEMENT: EAST 3 KT

3.A DVORAK ANALYSIS: 4.5/4.5/D 1.0/6 H

4.A CENTRAL PRESSURE: 978 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 65 KT
(RMW): 28 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 190 SE: 190 SW: 200 NW: 170
34 KT NE: 100 SE: 100 SW: 140 NW: 100
48 KT NE: 60 SE: 60 SW: 70 NW: 60
64 KT NE: 40 SE: 40 SW: 40 NW: 40

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 500 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP


1.B FORECASTS:
12H: 2019/03/11 06 UTC: 17.4 S / 43.3 E, VENT MAX= 080 KT, TROPICAL CYCLONE
24H: 2019/03/11 18 UTC: 18.2 S / 42.7 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE
36H: 2019/03/12 06 UTC: 18.9 S / 41.8 E, VENT MAX= 095 KT, INTENSE TROPICAL
CYCLONE
48H: 2019/03/12 18 UTC: 19.4 S / 40.8 E, VENT MAX= 100 KT, INTENSE TROPICAL
CYCLONE
60H: 2019/03/13 06 UTC: 19.7 S / 39.7 E, VENT MAX= 110 KT, INTENSE TROPICAL
CYCLONE
72H: 2019/03/13 18 UTC: 19.9 S / 38.5 E, VENT MAX= 105 KT, INTENSE TROPICAL CYCLONE

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/14 18 UTC: 19.5 S / 36.2 E, VENT MAX= 090 KT, INTENSE TROPICAL
CYCLONE
120H: 2019/03/15 18 UTC: 17.9 S / 34.6 E, VENT MAX= 050 KT, OVERLAND DEPRESSION

2.C ADDITIONAL INFORMATION:
T=CI=4.5-

DURING THE LAST 6 HOURS, THE SYSTEM HAS INTENSIFIED. IN INFRARED
IMAGERY, AN EYE FEATURE IS APPEARED AT 1400Z. THE LAST IMAGERIES SHOW
T-NUMBERS BETWEEN 5.5 AND 6. TO RESPECT DVORAK CONSTRAINT, CI IS
ESTIMATED AT 4.5-. ACCORDING WITH THE TRADITIONAL IMAGERY, 1544Z 91 GHZ
MICROWAVE IMAGERY SHOWS AN IMPROVING INTERNAL STRUCTURE WITH A
CENTRAL RING OF CONVECTION WELL FORMED.

WITH THE WEAKENING OF THE NEAR-EQUATORIAL RIDGE AND THE
STRENGTHENING OF THE SUBTROPICAL RIDGE, IDAI REMAINS IN CONDITIONS OF
ALMOST NO GUIDING FLOW. IT IS NECESSARY TO WAIT TOMORROW FOR THE
SYSTEM TO RESUME A SOUTWESTWARD TRACK ACCELERATING STEERED BY THE
SUBTROPICAL RIDGE. FROM WEDNESDAY, IDAI SHOULD BEND WESTWARD BEFORE
TO MAKE LANDFALL OVER MOZAMBIQUE COASTLINES THURSDAY NIGHT. MODELS
ARE IN GOOD AGREEMENT WITH THIS TRACK PHILOSOPHY. BUT MODELS
APPREHEND WITH DIFFICULTY THE CURVE SOUTHWESTWARD LINKED TO THE
STEERING FLOW CHANGING. SO, THE UNCERTAINTY ABOUT THE TIMING AND THE
LOCATION OF THE LANDFALL IS HIGH.

ON THIS TRACK, ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR GRADUAL
INTENSIFICATION. THE SYSTEM, SHOULD EVOLVE BENEATH THE UPPER LEVEL
RIDGE WITH A WEAK VERTICAL WINDSHEAR AND A GOOD POLERWARD
DIVERGENCE. OCEAN HEAT CONTENT IS VERY GOOD. THE PERIOD OF LIMITED
DISPLACEMENT OVER THE NEXT 24 HOURS WILL HOWEVER CONSUME THE
OCEAN'S ENERGY POTENTIAL AND WILL TEMPORARILY LIMIT THE
INTENSIFICATION BEFORE THE RESUMPTION OF THE IDAI'S DISPLACEMENT. IN
THESE CONDITIONS, THE LIKELIHOOD THAT A MATURE SYSTEM WITH A HIGH
INTENSITY MAKES LANDFALL OVER MOZAMBIQUE IS VERY HIGH.

[TorSkk]

A. 18S (IDAI)

B. 10/1730Z

C. 17.2S

D. 43.2E

E. ONE/MET-8

F. T4.0/4.0/D2.0/24HRS

G. IR/EIR/SWIR

H. REMARKS...EYE PATTERN WITH OW EYE SURROUNDED AND EMBEDDED WITHIN W
YIELDS A DT OF 6.5 AFTER 0.5 ADDED FOR AN EYE ADJUSTMENT. HOWEVER, THE
AVERAGE DT CALCULATED HOURLY FOR THE 6 HOURS ENDING AT 1730Z WAS 4.83,
WHICH DOES NOT JUSTIFY BREAKING CONSTRAINTS. MET=3.5 AND PT=4.0. FT IS
BASED ON CONSTRAINTS LIMITING CHANGES IN FT TO 1.0 OVER 6 HOURS.

I. ADDL POSITIONS

[Sciencerocks]

[TyphoonNara]

[TyphoonNara]

TPXS11 PGTW 110004

A. TROPICAL CYCLONE 18S (IDAI)

B. 10/2330Z

C. 17.29S

D. 43.33E

E. THREE/MET8

F. T5.0/5.0/D2.5/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 09A/PBO RAGGED EYE/ANMTN. OW EYE SURROUNDED BY LG
YIELDS AN E# OF 5.0. ADDED 0.5 EYE ADJUSTMENT FOR B, TO YIELD A
DT OF 5.5. MET YIELDS A 4.5 AND PT YIELDS A 5.0. DBO PT.

I. ADDITIONAL POSITIONS: NONE


BERMEA

[TyphoonNara]

Now a cat 3.

18S IDAI
As of 06:00 UTC Mar 11, 2019:

Location: 17.3°S 43.0°E
Maximum Winds: 100 kt
Minimum Central Pressure: 958 mb

[doomhaMwx]

Now a cat 3.

18S IDAI
As of 06:00 UTC Mar 11, 2019:

Location: 17.3°S 43.0°E
Maximum Winds: 100 kt
Minimum Central Pressure: 958 mb

[doomhaMwx]

[cycloneye]

 https://twitter.com/UWCIMSS/status/1105089370804183041

[TorSkk]

May become the first very intense tropical cyclone since Fantala '16


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

0.A WARNING NUMBER: 12/11/20182019

1.A INTENSE TROPICAL CYCLONE 11 (IDAI)

2.A POSITION 2019/03/11 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 17.6 S / 42.7 E

MOVEMENT: SOUTH-WEST 3 KT

3.A DVORAK ANALYSIS: 5.5/5.5/D 2.0/24 H

4.A CENTRAL PRESSURE: 955 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 95 KT
RADIUS OF MAXIMUM WINDS (RMW): 19 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 200 SE: 190 SW: 220 NW: 200
34 KT NE: 160 SE: 150 SW: 160 NW: 160
48 KT NE: 90 SE: 80 SW: 90 NW: 90
64 KT NE: 60 SE: 60 SW: 60 NW: 60

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 600 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2019/03/12 00 UTC: 18.1 S / 42.4 E, VENT MAX= 105 KT, INTENSE TROPICAL
CYCLONE
24H: 2019/03/12 12 UTC: 19.0 S / 41.8 E, VENT MAX= 115 KT, INTENSE TROPICAL
CYCLONE
36H: 2019/03/13 00 UTC: 19.4 S / 40.8 E, VENT MAX= 120 KT, VERY INTENSE TROPICAL
CYCLONE
48H: 2019/03/13 12 UTC: 19.8 S / 39.7 E, VENT MAX= 115 KT, INTENSE TROPICAL
CYCLONE
60H: 2019/03/14 00 UTC: 20.0 S / 38.4 E, VENT MAX= 105 KT, INTENSE TROPICAL
CYCLONE
72H: 2019/03/14 12 UTC: 19.9 S / 37.2 E, VENT MAX= 105 KT, INTENSE TROPICAL
CYCLONE

2.B LONGER-RANGE OUTLOOK:
96H: 2019/03/15 12 UTC: 19.0 S / 35.5 E, VENT MAX= 085 KT, TROPICAL CYCLONE
120H: 2019/03/16 12 UTC: 17.9 S / 34.8 E, VENT MAX= 035 KT, OVERLAND DEPRESSION

2.C ADDITIONAL INFORMATION:
T=CI=5.5+

OVER THE LAST 6 HOURS, IDAI'S EYE BECAME MORE AND MORE SYMMETRICAL
AND CLEARER ON THE IR AND VIS SATELLITE IMAGERY. THE LAST VIS IMAGES ARE
PARTICULARLY IMPRESSIVE. HOWEVER, THE DVORAK ESTIMATES DID NOT
INCREASE MUCH, ESPECIALLY BECAUSE OF RELATIVELY WARMER CLOUD TOPS
THAN THIS MORNING, WHICH COULD BE LINKED TO DIURNAL CYCLE PROCESSES
(CF CIMSS' DIURNAL CLOCK).

IDAI BEGINS TO ACCELERATE SOUTHWESTWARD WITH THE STRENGTHENING
INFLUENCE OF A SUBTROPICAL RIDGE LOCATED IN THE SOUTH-WEST. FROM
WEDNESDAY, THE TRACK SHOULD BEND WESTWARD. THE MAJORITY OF THE
AVAILABLE MODELS ALSO SUGGEST THAT THIS TURN COULD CONTINUE ON
THURSDAY, GIVING A NORTH-WESTWARD MOTION TO IDAI AT THE MOMENT OF ITS
IMPACT ON THE MOZAMBICAN COASTS. ONLY IFS (ECMWF) SUGGEST A LESS
SHARPER TURN WITH A WEST-NORTH-WESTWARD DIRECTION FROM FRIDAY. THE
TIMING AND LOCALISATION OF THE IMPACT THUS REMAIN RELATIVELY
UNCERTAIN, AS THE ALONG-TRACK MODEL DISPERSION ALSO INCREASED.
ON THIS TRACK, THE ENVIRONMENTAL CONDITIONS REMAIN CONDUCIVE FOR THE
SYSTEM, WHICH SHOULD CONTINUE TO STRENGTHEN, ESPECIALLY OVER THE
NEXT 48 H AS IT PASSES OVER AN OCEANIC GYRE CONCENTRATING HIGH ENERGY
CONTENT. THUS, THE VERY INTENSE TROPICAL CYCLONE STAGE MIGHT BE
REACHED. THE SYSTEM TRACKS UNDER THE AXIS OF AN UPPER RIDGE AND THUS
BENEFITS FROM A GOOD UPPER DIVERGENCE ESPECIALLY IN THE SOUTHERN
QUADRANT. AN EYEWALL REPLACEMENT CYCLE COULD ALSO MODULATE IDAI'S
INTENSITY. FROM WEDNESDAY, WITH A SIGNIFICANT DECREASE OF THE
EQUATORWARD DIVERGENCE, THE SYSTEM INTENSITY SHOULD REACH A PLATEAU.
IDAI SHOULD LAND AT THE INTENSE TROPICAL CYCLONE STAGE.

IDAI SHOULD BE A VERY DANGEROUS STORM AT THE TIME OF ITS LANDING, WHICH
IS STILL FORECASTED ON FRIDAY ON THE MOZAMBICAN COASTLINE BETWEEN
BEIRA AND QUELIMANE APPROXIMATELY. THE FIRST STORM SURGE ESTIMATIONS
EXCEED 6M OVER THE ZAMBEZE'S DELTA AND ARE CLOSE TO 4M AROUND BEIRA
AND QUELIMANE.