#162 Postby Crostorm » Sun Feb 19, 2012 9:11 pm
ZCZC 559
WTIO30 FMEE 200049
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 45/9/20112012
1.A SEVERE TROPICAL STORM 9 (GIOVANNA)
2.A POSITION 2012/02/20 AT 0000 UTC:
WITHIN 40 NM RADIUS OF POINT 26.0 S / 53.1 E
(TWENTY SIX DECIMAL ZERO DEGREES SOUTH AND FIFTY THREE DECIMAL ONE DEGREES EAST)
MOVEMENT : EAST 6 KT
3.A DVORAK ANALYSIS: 3.5/4.0/W 1.5/18 H
4.A CENTRAL PRESSURE: 988 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT
RADIUS OF MAXIMUM WINDS (RMW) :46 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 110 SE: 150 SW: 220 NW: 110
34 KT NE: 90 SE: 120 SW: 120 NW: 90
48 KT NE: 60 SE: 70 SW: 70 NW: 60
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM
1.B FORECASTS:
12H: 2012/02/20 12 UTC: 25.2 S / 53.8 E, MAX WIND=045 KT, MODERATE TROPICAL STORM
24H: 2012/02/21 00 UTC: 24.5 S / 53.2 E, MAX WIND=035 KT, MODERATE TROPICAL STORM
36H: 2012/02/21 12 UTC: 23.8 S / 52.3 E, MAX WIND=025 KT, TROPICAL DISTURBANCE
48H: 2012/02/22 00 UTC: 22.8 S / 51.9 E, MAX WIND=020 KT, LOW
60H: 2012/02/22 12 UTC: 21.6 S / 51.6 E, MAX WIND=020 KT, LOW
72H: 2012/02/23 00 UTC: 20.5 S / 51.3 E, MAX WIND=020 KT, DISSIPATING
2.B LONGER-RANGE OUTLOOK :
2.C ADDITIONAL INFORMATIONS:
T= 3.5 AND CI=4.0
IR IMAGERY SHOWS THAT GIOVANNA BECOMES TO UNDERGO A STRONG WESTERLY TO NORTH-WESTERLY WINDSHEAR. D
ESTRUCTURATION OF PATTERN IS FAST. LLCC IS DIFFICULT TO LOCALIZE (NO RECENT MW PICTURE) BUT SYSTEM
HAS LIKELY HIGHLY DECELERATE.
SYSTEM MIGHT KEEP ON TRACKING EAST-NORTHEASTWARD WITHIN THE NEXT HOURS BY CONTINUING TO WEAKEN RAP
IDLY. SO, ITS STEERING FLOW IS EXPECTED TO MOVE IN LOWER TROPOSPHERE. BEYOND, NWP MODELS ARE NOT I
N GOOD AGREEMENT LIKE ECMWF ENSEMBLE RUN. TWO OPTIONS ARE POSSIBLE. A SOUTH-SOUTHEASTWARD RECURVE
OR A NORTH-NORTHWESTWARD RECURVE. RSMC KEEPS NORTHWARD OPTION (RIDGE SITUATED IN THE WEST THEN SOU
TH-WEST OF THE SYSTEME).
ON THIS FORECAST TRACK, ENVIRONMENTAL CONDITIONS ARE VERY DEFAVOURABLE WITH A STRONG WESTERLY THEN
SOUTH-WESTERLY VERTICAL WIND SHEAR DUE TO AN UPPER TROPOSPHERIC TROUGH TRANSITING SOUTH-EAST OF M
ADAGASCAR.
THE RESIDUAL LOW IS FORECAST TO FILL UP ON WEDNESDAY, WITHIN A BROAD AREA OF LOW PRESSURE OVER THE
MASCARENE ISLANDS.
NNNN
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