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本帖最後由 Meow 於 2016-10-5 09:57 編輯
WTIO30 FMEE 050042
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 1/2/20162017
1.A SUBTROPICAL DEPRESSION 2 (BRANSBY)
2.A POSITION 2016/10/05 AT 0000 UTC:
WITHIN 20 NM RADIUS OF POINT 29.7 S / 43.6 E
(TWENTY NINE DECIMAL SEVEN DEGREES SOUTH AND FORTY THREE DECIMAL SIX DEGREES EAST)
MOVEMENT : WEST 5 KT
3.A DVORAK ANALYSIS: NIL
4.A CENTRAL PRESSURE: 993 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW) :56 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 90 SE: 740 SW: 460 NW: 110
34 KT NE: 60 SE: 560 SW: 280 NW: 60
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : SHALLOW
1.B FORECASTS:
12H: 2016/10/05 12 UTC: 29.5 S / 42.9 E, MAX WIND=040 KT, SUBTROPICAL DEPRESSION
24H: 2016/10/06 00 UTC: 30.2 S / 44.6 E, MAX WIND=035 KT, SUBTROPICAL DEPRESSION
36H: 2016/10/06 12 UTC: 31.9 S / 45.9 E, MAX WIND=030 KT, EXTRATROPICAL SYSTEM
2.B LONGER-RANGE OUTLOOK :
2.C ADDITIONAL INFORMATION:
DURING THE LAST DAYS, A BAROCLINIC LOW FORMED SOUTH OF THE MOZAMBIQUE CHANNEL, INTERACTING WITH AN UPPER TROUGH. SINCE YESTERDAY, THIS LOW STARTED TO GAIN TROPICAL CHARACTERISTICS, WHILE MOVING UNDER THE TROUGH, AVOIDING VERTICAL WIND SHEAR. OVER THE LAST HOURS, DRIVEN BY THE COLD UPPER AIR AND THE ACTIVE PHASE OF DIURNAL CONVECTION ON SEA, DEEP CONVECTION GOT STRONGER NEAR THE CENTER, HELPING BUILDING A SHALLOW WARM CORE. A WARM SPOT IS ALSO VISIBLE IN THE LAST IMAGERY. MOREOVER, LAST ASCAT SWATH (1823Z) SHOW A 35KT LOW LEVEL CIRCULATION WITH MAXIMAL WINDS NEAR THE CORE. THUS, MALAGASY WEATHER SERVICE, NAMED THE SUBTROPICAL DEPRESSION BRANSBY AT 00Z.
THE SYSTEM IS NOW MOVING WEST ON THE NORTHERN SIDE OF A HIGH GEOPOTENTIALS AREA. BRANSBY IS LIKELY TO CONTINUE IN THIS DIRECTION UP TO TONIGHT, AND THEN GO EASTWARD AND SOUTHEASTWARD WITH THE ARRIVAL OF A NEW TROUGH AT SOUTH-WEST. MAIN MODEL GUIDANCE IS IN AGREEMENT WITH THIS FORECAST.
ON THIS TRACK, BRANSBY IS UNLIKELY TO UNDERGO A COMPLETE TROPICAL TRANSITION, WITH COLD WATERS REMAINING AROUND 20C. A SHORT PERIOD FOR DEEPENING STILL EXISTS TODAY, THANKS TO A GOOD UPPER DIVERGENCE AND LATE NIGHT CONVECTIVE THRUSTS. BUT FROM TOMORROW, THE SYSTEM IS LIKELY TO EVOLVE IN A LESS CONDUCIVE UPPER ENVIRONMENT (NORTH- WESTERLY CONSTRAINT), WHICH MAY CAUSE A RAPID DISORGANIZATION AND DISSIPATION OF THE LOW BY FRIDAY. |
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