SWIO: Ava - Extratropical

[Digital-TC-Chaser]

JTWC cutting it close with a non landfalling hurricane forecast

[doomhaMwx]

GFS and ECMWF have Ava lingering around/over Madagascar for the next 10 days.

[Digital-TC-Chaser]

WTIO22 FMEE 041814
SECURITE
STORM WARNING FOR METAREA VII AND METAREA VIII (S)
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTER/LA REUNION 04/01/2018
AT
1800 UTC.
WARNING NUMBER: 020/1 (SOUTH-WEST INDIAN OCEAN)

10 MINUTES AVERAGE WIND SPEED IN KNOTS (KT)
(WIND GUSTS AT SEA MAY BE ABOUT 40% STRONGER THAN THE AVERAGED WIND)
MINIMUM SEA LEVEL PRESSURE IN HECTOPASCAL (HPA)
(INDICATIVE FIGURE).

STORM WARNING
BEGINNING OF VALIDITY: THURSDAY 04/01/2018 AT 1800 UTC.

PHENOMENON: SEVERE TROPICAL STORM 1 (AVA) 978 HPA
POSITION: WITHIN 20 NM RADIUS OF POINT 17.1 S / 50.9 E
(SEVENTEEN DECIMAL ONE DEGREES SOUTH AND
FIFTY DECIMAL NINE DEGREES EAST) AT 1800 UTC
MOVEMENT: WEST 6 KT

THREAT AREAS:
SQUALLY WEATHER IN A 120 NM RADIUS FROM THE CENTER.
STORM FORCE WINDS 50/60 KT AND HIGH TO VERY HIGH SEAS WITHIN A 35 NM
RADIUS FROM THE CENTRE.
GALE FORCE WINDS 35/45 KT AND VERY ROUGH TO HIGH SEAS WITHIN A 50 NM
RADIUS FROM THE CENTRE, EXTENDING UP TO 80 NM IN THE SOUTHERN
SEMI-CIRCLE AND THE NORTH-EASTERN QUADRANT.
NEAR GALE FORCE WINDS 30 KT AND ROUGH TO VERY ROUGH SEAS WITHIN A 80
NM RADIUS FROM THE CENTRE, EXTENDING UP TO 120 NM IN THE SOUTHERN
SEMI-CIRCLE AND THE NORTH-EASTERN QUADRANT.
STRONG GUSTS UNDER SQUALLS.
FORECAST POSITION AND INTENSITY:
12H, VALID 2018/01/05 AT 06 UTC:
17.7 S / 49.6 E, MAX WIND = 65 KT, TROPICAL CYCLONE
24H, VALID 2018/01/05 AT 18 UTC:
18.5 S / 49.1 E, MAX WIND = 45 KT, OVERLAND DEPRESSION

WTIO30 FMEE 041836 RRB
OVER THE LAST 6 HOURS, DEEP CONVECTION COLD CLOUD TOPS REMAINED NEAR
THE CENTER. LAST MICROWAVE DATA (WINDSAT 1431Z AND SSMIS F17 1519Z)
SHOW AN IMPROVEMENT OF THE INNER CORE AND A CONTRACTION OF THE RADIUS
OF MAXIMUM WINDS. THEREFORE, IN AGREEMENT WITH LAST DVORAK ESTIMATES,
ANALYSED INTENSITY WAS INCREASED.
DURING THE LAST HOURS, THE ARRIVAL OF A FAST RIDGE SOUTH OF
MADAGASCAR ALLOWED TO THE SYSTEM TO KEEP WESTWARD TRACK. THUS, AVA
LANDING IS EXPECTED TO HAPPEN TOMORROW MORNING, NORTH OF THE PREVIOUS
FORECAST, BETWEEN TOAMASINA AND SAINTE MARIE ISLAND. IT IS STILL
EXPECTED TO DEEPEN UP TO THE COASTLINE AND SO REACH THE TROPICAL
CYCLONE STATUS.
AVA IS A THREATENING SYSTEM AND A SIGNIFICANT DETERIORATION OF THE
CONDITIONS IS EXPECTED IN THE LANDFALL REGION. A CYCLONIC SURGE OF
ABOUT 1.5M TO 2M IS FORECAST ESPECIALLY IN THE AREAS SOUTH OF THE
CENTER.
ON FRIDAY, WITH THE SHIFT OF THE FAST RIDGE, AVA IS LIKELY TO GO
SOUTH. THERE IS STILL A LARGE UNCERTAINTY ON THE DURATION OF THE
INLAND PHASE WITH THE PARALLEL TO THE COASTLINE TRACK AND SO ABOUT
THE INTENSITY OF THE SYSTEM AT ITS COME BACK OVER SEAS. AT LONG
RANGE, A NEW POALR TROUGH AT SOUTH MAY SLOW DOWN THE SYSTEM AND
TEMPORARILY STEER IT EASTWARD. THE PRESENT FORECAST IS MOSTLY BASED
ON AN IFS/GFS CONSENSUS.
WHEN EXITING OVER THE OCEAN, AVA MAY ENCOUNTER VERY FAVORABLE
ENVIRONMENTAL CONDITIONS FOR A NEW INTENSIFICATION PHASE WITH A GOOD
UPPER LEVEL DIVERGENCE AHEAD AN UPPER LEVEL TROUGH AND A LOW VERTICAL
WINDSHEAR. ALONG THE FORECAST TRACK, THE OCEANIC HEAT POTENTIAL
UNDERNEATH REMAINS CONDUCIVE NORTH OF 25S AND ONLY THE VICINITY OF

[Digital-TC-Chaser]

WTIO22 FMEE 050016
PANPAN
HURRICANE WARNING FOR METAREA VII AND METAREA VIII (S)
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTER/LA REUNION 05/01/2018
AT
0000 UTC.
WARNING NUMBER: 021/1 (SOUTH-WEST INDIAN OCEAN)

10 MINUTES AVERAGE WIND SPEED IN KNOTS (KT)
(WIND GUSTS AT SEA MAY BE ABOUT 40% STRONGER THAN THE AVERAGED WIND)
MINIMUM SEA LEVEL PRESSURE IN HECTOPASCAL (HPA)
(INDICATIVE FIGURE).

HURRICANE WARNING
BEGINNING OF VALIDITY: FRIDAY 05/01/2018 AT 0000 UTC.

PHENOMENON: TROPICAL CYCLONE 1 (AVA) 973 HPA
POSITION: WITHIN 20 NM RADIUS OF POINT 17.2 S / 50.6 E
(SEVENTEEN DECIMAL TWO DEGREES SOUTH AND
FIFTY DECIMAL SIX DEGREES EAST) AT 0000 UTC
MOVEMENT: WEST-SOUTH-WEST 4 KT
THREAT AREAS:
SQUALLY WEATHER IN A 150 NM RADIUS FROM THE CENTER.
HURRICANE FORCE WINDS 65 KT AND VERY HIGH TO PHENOMENAL SEAS WITHIN A
20 NM RADIUS FROM THE CENTRE.
STORM FORCE WINDS 50/60 KT AND HIGH TO VERY HIGH SEAS WITHIN A 40 NM
RADIUS FROM THE CENTRE.
GALE FORCE WINDS 35/45 KT AND VERY ROUGH TO HIGH SEAS WITHIN A 70 NM
RADIUS FROM THE CENTRE, EXTENDING UP TO 80 NM IN THE NORTHERN
SEMI-CIRCLE AND UP TO 90 NM IN THE SOUTH-WESTERN QUADRANT.
NEAR GALE FORCE WINDS 30 KT AND ROUGH TO VERY ROUGH SEAS WITHIN A 85
NM RADIUS FROM THE CENTRE, EXTENDING UP TO 100 NM IN THE NORTHERN
SEMI-CIRCLE AND UP TO 120 NM IN THE SOUTH-WESTERN QUADRANT.
STRONG GUSTS UNDER SQUALLS.
FORECAST POSITION AND INTENSITY:
12H, VALID 2018/01/05 AT 12 UTC:
17.9 S / 49.3 E, MAX WIND = 65 KT, OVERLAND DEPRESSION
24H, VALID 2018/01/06 AT 00 UTC:
19.2 S / 48.9 E, MAX WIND = 45 KT, OVERLAND DEPRESSION

OTHER INFORMATIONS:
NIL.=

[Digital-TC-Chaser]

Tropical Cyclone Intensity Estimation Algorithm
RSMC Initialized


Current Intensity Analysis



UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 05 JAN 2018 Time : 001500 UTC
Lat : 17:12:23 S Lon : 50:33:05 E


CI# /Pressure/ Vmax
4.6 / 965.7mb/ 79.6kt


Final T# Adj T# Raw T#
4.5 4.1 4.0

Latitude bias adjustment to MSLP : +2.1mb

Center Temp : -70.9C Cloud Region Temp : -77.0C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : INDIAN
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF

Satellite Name : MSG1
Satellite Viewing Angle : 22.7 degrees

JTWC best track
03S AVA 180105 0000 17.2S 50.5E SHEM 75 975

[Yellow Evan]

Pretty clear T4.5 to me.

And for once JTWC agrees with me

PXS11 PGTW 050306

A. TROPICAL CYCLONE 03S (AVA)

B. 05/0230Z

C. 17.40S

D. 50.43E

E. THREE/MET8

F. T4.5/4.5/D2.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 09A/PBO RAGGED EYE/ANMTN. MG EYE SURROUNDED BY B
YIELDS AN E# AND DT (NO EYE ADJUSTMENT) OF 4.5. MET YIELDS 4.0,
WHILE PT YIELDS 4.5. DBO DT.

I. ADDITIONAL POSITIONS:
04/2148Z 17.15S 50.70E ATMS
04/2256Z 17.22S 50.70E GPMI
05/0006Z 17.25S 50.68E SSMS
05/0024Z 17.27S 50.67E MMHS


LOWE

SAB does not however

04/2330 UTC 17.1S 50.7E T5.0/5.0 AVA -- Southwest Indian

[Digital-TC-Chaser]

Definitely looking more tidy now.

TXXS22 KNES 050625
TCSSIO

A. 03S (AVA)

B. 05/0530Z

C. 17.8S

D. 50.1E

E. ONE/MET-8

F. T5.0/5.0/D1.5/24HRS

G. IR/EIR/VIS

H. REMARKS...EYE PATTERN WITH DG EYE SURROUNDED BY B AND EMBEDDED BY
LG YIELDS A DT OF 5.0. THERE WERE NO EYE ADJUSTMENTS. MET AND PT ALSO
AGREE. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...KIM

[Digital-TC-Chaser]

[MSG1 23.0
2018JAN05 034500 4.9 965.9 87.4 4.9 5.9 6.1 1.3T/6hr OFF OFF -20.85 -75.02 EYE/P -99 IR 48.5 -17.68 -50.41 SPRL MSG1 23.1
2018JAN05 041500 5.1 962.0 92.4 5.1 5.9 6.0 1.3T/6hr OFF OFF -20.12 -73.31 EYE/P -99 IR 48.5 -17.79 -50.37 SPRL MSG1 23.2
2018JAN05 044500 5.3 958.2 97.2 5.3 5.7 5.7 NO LIMIT OFF OFF -38.21 -71.65 EYE -99 IR 48.5 -17.81 -50.23 SPRL MSG1 23.1
2018JAN05 053000 5.5 954.3 102.0 5.5 5.7 5.7 NO LIMIT OFF OFF -40.18 -72.10 EYE -99 IR 48.5 -17.84 -50.18 SPRL MSG1 23.1
2018JAN05 054500 5.5 954.3 102.0 5.5 5.6 5.6 NO LIMIT OFF OFF -41.44 -71.98 EYE -99 IR 48.5 -17.85 -50.06 SPRL MSG1 23.1

Conventional sat suggesting it now a major hurricane.

[euro6208]

03S AVA 180105 0600 17.9S 50.0E SHEM 95 958

[Digital-TC-Chaser]

eye cleared

[WAcyclone]

Toamasina (which is the second-largest city in Madagascar) just reported solid hurricane conditions and a pressure of 979 mb. This station will likely go through the eye within the next few hours.

METAR FMMT 050900Z 20064G74KT 2500 +RA SCT007 SCT017TCU OVC033 25/25 Q0979 TEMPO 1000

[doomhaMwx]

Toamasina city in Ava's eye...

[WAcyclone]

Toamasina is indeed right inside the eye with reports of sunshine coming out of the city. Lowest reported pressure was 965 mb with 8 kt sustained winds.

 https://twitter.com/Cycloneoi/status/949241548205625344

[cycloneye]

@iCyclone
Eye of #Cyclone #AVA passing directly over #Toamasina (#Tamatave) at 2 pm local time. Winds 95 knots (Cat 2). First direct for #Madagascar’s largest port city in a long while.

 https://twitter.com/iCyclone/status/949253907561119750

[cycloneye]

@metoffice
Tropical Cyclone #Ava will continue to bring strong winds and heavy rain across parts of #Madagascar, with up to 5 times the average January rainfall, leading to severe flooding and landslides

 https://twitter.com/metoffice/status/949699295929913345

[cycloneye]

21:00 UTC warning from JTWC at 40 kts.

[1900hurricane]

Here's MFr's latest bulletin.

WTIO30 FMEE 061835
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 28/1/20172018
1.A OVERLAND DEPRESSION 1 (EX-AVA)
2.A POSITION 2018/01/06 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 21.1 S / 47.5 E
(TWENTY ONE DECIMAL ONE DEGREES SOUTH AND FORTY SEVEN DECIMAL FIVE
DEGREES EAST)
MOVEMENT : SOUTH 6 KT
3.A DVORAK ANALYSIS: NIL
4.A CENTRAL PRESSURE: 995 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: 460 SE: 460 SW: NW:
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1003 HPA / 1200 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM
1.B FORECASTS:
12H: 2018/01/07 06 UTC: 22.6 S / 47.9 E, MAX WIND=030 KT, OVERLAND DEPRESSION
24H: 2018/01/07 18 UTC: 24.2 S / 48.1 E, MAX WIND=035 KT, MODERATE TROPICAL
STORM
36H: 2018/01/08 06 UTC: 25.4 S / 47.9 E, MAX WIND=040 KT, MODERATE TROPICAL
STORM
48H: 2018/01/08 18 UTC: 26.5 S / 47.1 E, MAX WIND=035 KT, MODERATE TROPICAL
STORM
60H: 2018/01/09 06 UTC: 28.1 S / 47.2 E, MAX WIND=035 KT, MODERATE TROPICAL
STORM
72H: 2018/01/09 18 UTC: 29.2 S / 49.1 E, MAX WIND=030 KT, TROPICAL DEPRESSION
2.B LONGER-RANGE OUTLOOK :
96H: 2018/01/10 18 UTC: 31.4 S / 54.6 E, MAX WIND=030 KT, EXTRATROPICAL
DEPRESSION
120H: 2018/01/11 18 UTC: 35.4 S / 64.4 E, MAX WIND=030 KT, EXTRATROPICAL
DEPRESSION
2.C ADDITIONAL INFORMATION:
EX-AVA KEEPS ON TRACKING OVER MADAGASCAR AND IS DELAYING ITS RETURN
OVER SEA. THIS OVERLAND TRACK LONGER THAN ANTICIPATED IS AFFECTING THE
SYSTEM INTENSITY WHICH NOW ONLY PRODUCES NEAR GALE FORCE WINDS
ALONG THE EASTERN MALAGASY COASTLINE. THE CENTER IS ESTIMATED IN EAST
EDGE OF THE DEEP CONVECTION EITHER A NEAR 50KM IN THE LAND.
STEERED BY THE RIDGE IN THE EAST AND A MID-LATITUDE TROUGH ATTRACTING
IT IN THE SOUTH, EX-AVA SHOULD SLIGHTLY CURVE SOUTH-SOUTH-EASTWARD
AND COME BACK OVER SEA DURING SUNDAY. FROM TUESDAY, THE ENSEMBLE
PREDICTION STILL SHOWS TWO POSSIBLE SCENARIOS : EITHER THE SYSTEM IS
BLOCKED BY THE ARRIVAL OF THE NEW HIGH PRESSURE CELL IN THE SOUTH OR
TAKEN AWAY BY THE WESTERLIES. THUS, THE UNCERTAINTY REMAINS HIGH FROM
TUESDAY. THE SECOND OPTION HAS BEEN CHOSEN TO BE THE RSMC OFFICIAL
FORECAST AS THE EUROPEAN ENSEMBLE PREDICTION SLIGHTLY FAVOURS THIS
SCENARIO.
WHEN EXITING OVER THE OCEAN, EX-AVA MAY ENCOUNTER FAVORABLE
CONDITIONS BUT ITS LONG TRACK ON MALAGASY LANDS HAS STRONGLY
WEAKENED THE SYSTEM. ITS REINTENSIFICATION PHASE WILL BE LABOROUS AND
FROM TUESDAY, A MODERATE TO STRONG EASTERLY SHEAR IS AFFECTING EX-AVA
WHILE THE OCEANIC POTENTIAL BECOMES LIMITED SOUTH OF 25S. THE SYSTEM
SHOULD THEN BEGIN TO WEAKEN GRADUALLY WHILE TRANSFORMING INTO A
BAROCLINIC LOW UNDER THE INFLUENCE OF AN UPPER TROUGH COMING FROM
THE WEST.

[cycloneye]

40 kts.

[doomhaMwx]

03S AVA 180108 0600 25.4S 49.1E SHEM 40 989

[Digital-TC-Chaser]

https://www.nasa.gov/feature/goddard/20 ... dian-ocean