2 Active tropical cyclones in Southern Indian Ocean.

Image
#AmaraCyclone:

WARNING POSITION: NEAR 18.3S 65.3E
MOVEMENT PAST SIX HOURS – 250 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 025 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS – 110 KT, GUSTS 135 KTs

REMARKS:

Tropical cyclone (TC) 03S (AMARA), located approximately 565NM East-Northeast of Reunion Island, has tracked West-Southwest ward at 06 knots over the past six hours. Recent animated multispectral satellite imagery depicts a small, compact system with tightly curvec banding wrapping around the system centre and spiralling out from the low- level circulation centre (LLCC).
Image depicts very intense and deep convection nearly encompassing the entire LLCC with slightly warmer clouds tops over the western semicircle of the eyewall. The current position is based on the apparent 30NM symmetric eye with high confidence. The current intensity is based on an average of dvorak estimates ranging from 102 – 115 knots. Upper- level analysis indicates the system is underneath a self-induced point source of divergence which is provding for low ( 05 – 10 knot ) vertical wind shear and good divergence aloft.

Animated water-vapour imagery indicates the main outflow channel in the poleward direction into a transitory trough to the southeast with a moderated equatorward channel as well.TC 03S is forecast to round the western periphery of the subtropical ridge (STR) located to the southeast as the transitory mid-latitude trough to the southeast of the system continues to break down the STR.

Another fast moving mid-latitude trough, now located southwest of the system, will further break down the western periphery of the STR. TC 04S (BRUCE), will have reached CPA from TC 03S (AMARA) and will continue to track away. Model fields depict an extension of the low- to mid – level near equatorial ridge building in the northeast of the system. At the same time a low- to mid-level STR will build in southeast of Madagascar. Most model fields show these two combining to form a continuous STR lobe that should remain south and east of the cyclone. All of the statictical- dynamical intensity guidance weakens the system throughout the forecast period and only the purely dynamical guidance intensifies it. Even though a temporary intensification may occur with the passage of the transitory mid- latitude troughs and their accentuation of the poleward outflow, the forecast calls for an overall weakening trend.
Increasingly vertical wind shear ahead of the troughs and dry air entrainment with the establishment of the low-to mid-level STR should prove enough to bring the system to eventual dissipation track guidance remains widely spread due to each model’s various timing of all the previously mentioned synoptic evolutions.
THEREFORE, low confidence remain in the official forecast. There is the possibility that the weakened LLCC may retrograde to the west during the fout to five day mark but should be dissipating by this time anyway.

#Rodrigues island may pass from a warning class 3 to 4 late night.
Lnk for animated cyclon tracking: http://sirocco.accuweather.com/sat_mosaic_640x480_public/ir/isaindo.gif

 

 

 

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