SIO: DAYA - Post-Tropical

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ZCZC 195
WTIO30 FMEE 081326 CCA
***************CORRECTIVE**************
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 1/4/20152016
1.A TROPICAL DISTURBANCE 4
2.A POSITION 2016/02/08 AT 1200 UTC:
WITHIN 40 NM RADIUS OF POINT 18.8 S / 53.1 E
(EIGHTEEN DECIMAL EIGHT DEGREES SOUTH AND FIFTY THREE DECIMAL
ONE DEGREES EAST)
MOVEMENT : SOUTH-WEST 15 KT
3.A DVORAK ANALYSIS: 2.0/2.0/D 0.5/6 H
4.A CENTRAL PRESSURE: 1002 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 25 KT
RADIUS OF MAXIMUM WINDS (RMW) :NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : SHALLOW
1.B FORECASTS:
12H: 2016/02/09 00 UTC: 19.5 S / 51.5 E, MAX WIND=025 KT, TROPICAL
DISTURBANCE
24H: 2016/02/09 12 UTC: 21.3 S / 51.2 E, MAX WIND=025 KT, TROPICAL
DISTURBANCE
36H: 2016/02/10 00 UTC: 22.2 S / 51.4 E, MAX WIND=030 KT, TROPICAL
DEPRESSION
48H: 2016/02/10 12 UTC: 22.9 S / 51.7 E, MAX WIND=030 KT, TROPICAL
DEPRESSION
60H: 2016/02/11 00 UTC: 23.6 S / 52.2 E, MAX WIND=030 KT, TROPICAL
DEPRESSION
72H: 2016/02/11 12 UTC: 24.8 S / 52.8 E, MAX WIND=030 KT, TROPICAL
DEPRESSION
2.B LONGER-RANGE OUTLOOK :
96H: 2016/02/12 12 UTC: 30.3 S / 54.2 E, MAX WIND=035 KT,
POST-TROPICAL DEPRESSION
120H: 2016/02/13 12 UTC: 39.4 S / 56.8 E, MAX WIND=035 KT,
POST-TROPICAL DEPRESSION
2.C ADDITIONAL INFORMATION:
T=CI=2.0-
A LOW LEVEL CIRCULATION HAS GRADUALLY EMERGED OVERNIGHT, NORTH OF THE
MASCAREIGNES ARCHIPELAGO. IN THIS AREA, A CLEAR IMPROVEMENT OF THE
CONVECTION PATTERN WAS ALSO VISIBLE ON THE IR IMAGERY. THE ISOLATED
CONVECTIVE BURSTS HAVE MERGED TO FORM A LARGE AREA OF VERY COLD CLOUD
TOPS. FROM 09Z, A CURVED BAND HAS BEGUN TO EMERGE IN THE
SOUTH-WESTERN QUADRANT. THE 0553Z ASCAT SWATH ONLY COVERS THE EASTERN
HALF OF THE CIRCULATION BUT SUGGESTS THAT LOW LEVELS CIRCULATION
STRUCTURE IS IMPROVING, WITH WINDS LOCALLY REACHING 25KT IN THE
GRADIENT, WHICH JUSTIFY A TROPICAL DISTURBANCE STAGE.
LOCATED UNDER THE AXIS OF AN UPPER LEVEL RIDGE, THE LOW BENEFITS FROM
A RATHER CONDUCIVE UPPER LEVEL ENVIRONMENT, WITH EVEN A GOOD
DIVERGENCE ON THE SOUTHERN SIDE. THE LLCC IS HIDDEN UNDER A THICK
CLOUD COVER, ESPECIALLY CIRRUS CLOUDS, MAKING ITS LOCALIZATION
APPROXIMATE.
NWP MODELS ARE IN RATHER GOOD AGREEMENT TO FORECAST A PARABOLIC
TRACK, THE SYSTEM SHOULD THUS PASS BETWEEN MADAGASCAR AND THE REUNION
ISLAND BEFORE TURNING SOUTHWARD TUESDAY AND THEN SOUTH-EASTWARD FROM
WEDNESDAY, STEERED INTO THE MID-LATITUDES BY A BAROCLINIC LOW WHICH
CRAWLS ITS WAY SOUTHWARD BETWEEN TWO HIGH PRESSURE AREAS. ALONG THIS
TRACK, THE LOW SHOULD DEEPEN SLOWLY UNDER STILL QUITE CONDUCIVE UPPER
LEVELS CONDITIONS BUT WITH A LOT LESS EFFICIENT LOW LEVEL
CONVERGENCE. THE SYSTEM SHOULD NOT REACH THE MODERATE TROPICAL STORM
STAGE IN THE NEXT DAYS, BUT WE NOTE THAT THE AVAILABLE MODEL GUIDANCE
IS NOT YET IN AGREEMENT REGARDING THE EXACT LEVEL OF DEEPENING.
THE CURRENT INTENSITY OF THE SYSTEM DOES NOT JUSTIFY THE ISSUANCE OF
REGULAR WARNINGS.=
NNNN

[Darvince]

[jaguarjace]

ZCZC 217
WTIO30 FMEE 101802
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 6/4/20152016
1.A MODERATE TROPICAL STORM 4 (DAYA)
2.A POSITION 2016/02/10 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 24.0 S / 52.6 E
(TWENTY FOUR DECIMAL ZERO DEGREES SOUTH AND FIFTY TWO DECIMAL
SIX DEGREES EAST)
MOVEMENT : SOUTH-EAST 8 KT
3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/24 H
4.A CENTRAL PRESSURE: 993 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW) :46 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 130 SE: 130 SW: 90 NW: 90
34 KT NE: 60 SE: 60 SW: 60 NW: 60
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1003 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP
1.B FORECASTS:
12H: 2016/02/11 06 UTC: 25.1 S / 54.1 E, MAX WIND=035 KT, MODERATE
TROPICAL STORM
24H: 2016/02/11 18 UTC: 26.9 S / 55.5 E, MAX WIND=040 KT, MODERATE
TROPICAL STORM
36H: 2016/02/12 06 UTC: 29.3 S / 56.7 E, MAX WIND=040 KT,
POST-TROPICAL DEPRESSION
48H: 2016/02/12 18 UTC: 32.9 S / 58.3 E, MAX WIND=040 KT,
POST-TROPICAL DEPRESSION
60H: 2016/02/13 06 UTC: 37.9 S / 61.3 E, MAX WIND=040 KT,
POST-TROPICAL DEPRESSION
2.B LONGER-RANGE OUTLOOK :
2.C ADDITIONAL INFORMATION:
T=CI=2.5+
OVER THE LAST SIX HOURS, THE CLOUD PATTERN HAS KEPT ON IMPROVING WITH
A CURVED BAND WRAPING A LITTLE MORE THAN 0.5 AROUND THE CENTRE,
BECOMING LARGER, AS SEEN ON THE 1109Z AND 1250Z SSMI MICRO-WAVE
IMAGES, AND WITH A BETTER CURVATURE OF THE LOW LEVEL AS SEEN ON THE
DMPS-F17 37GHZ DATA.
ALL THESE OBSERVATION DATA SUGGEST THAT THE SYSTEM HAS REACHED THE
MODERATE TROPICAL STORM STAGE, AND HAS BEEN NAMED.
THE UPPER LEVEL CONDITIONS REMAIN CONDUCIVE WITH AN OUTFLOW CHANNEL
BUILDING ON THE POLAR SIDE. INTENSIFICATION SHOULD GOING ON DURING
THE NEXT 24 HOURS.
THE PARABOLIC TRACK OF THE SYSTEM IS STEERED BY BOTH A CUT-OFF LOW IN
THE SOUTH-WEST AND A HIGH GEOPOTENTIAL AREA IN THE EAST. UNDER THE
JOINED INFLUENCE OF THESE TWO SYNOPTIC STRUCTURES, THE AVAILABLE NWP
MODELS STILL FORECAST SIMILAR TRACKS BUT WITH A LIGHT DISPERSION
INCREASE DUE TO SOME ANALYSIS DIFFERENCES. THUS, THE SYSTEM HAS
ALREADY TURNED SOUTH-EASTWARD AND BEGAN TO ACCELERATE. THE
ENVIRONMENTAL CONDITIONS REMAIN CONDUCIVE UNTIL THURSDAY EVENING.
FRIDAY, THE SYSTEM IS TRACKING OVER LOW ENERGETIC WATERS AND SHIFTS
GRADUALLY UNDER A BRANCH OF THE SUBTROPICAL WESTERLY JET. IT SHOULD
THEN BEGIN A RELATIVELY QUICK EXTRATROPICAL TRANSITION BEFORE MERGING
WITH A BAROCLINIC LOW SATURDAY.=
NNNN

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