February 4th, 2013 Category: Tropical Cyclones

Tropical Cyclone Felleng (13S) – February 3rd, 2013

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Track of TC 13S

Upper level analysis indicates an approaching mid-latitude trough and an upper level low to the south of Madagascar are interacting with the subtropical high to the north of Tropical Cyclone Felleng (13S), creating high levels (30 to 40 knots) of vertical wind shear (VWS) over the LLCC. This interaction is also enhancing the steering flow, keeping Felleng on a quick but steady track to the south-southeast.

Increasing VWS and decreasing SST values will lead TC 13S to be fully extra-tropical by TAU 12. There is high confidence in the forecast track based on good model consistency. The system will be closely monitored for signs of regeneration. Maximum significant wave height is 20 feet.

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February 4th, 2013 Category: Tropical Cyclones

Tropical Cyclone Felleng (13S) – February 3rd, 2013

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Track of TC 13S

Tropical Cyclone Felleng (13S), located approximately 745 nm south of La Reunion has tracked south-southeastward at 15 knots over the past six hours.

Animated infrared satellite imagery shows all associated convection with the low level circulation center (LLCC) has been sheared to the southeast by approximately 175 nm. Older ASCAT passes indicate the LLCC has started to expand with the strongest winds located further from the center of the system.

The system has been located over sea surface temperatures (SST) between 23 to 24 degrees Celsius, directly impacting the warm central core. Felleng has begun the extra-tropical transition process and within the next 12 hours the SST values will drop below 20 degrees Celsius, accelerating the transition to a cold core system.

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February 3rd, 2013 Category: Image of the day, Tropical Cyclones

Tropical Cyclone Felleng (13S) – February 2nd, 2013

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Track of TC 13S

Tropical Cyclone Felleng (13S), is tracking along the western edge of a subtropical high (STH) to the east. Here, it can be seen southwest of Madagascar, which is partially visible in the upper left corner.

A shortwave trough currently digging the western flank of the system is expected to weaken the STH and cause the cyclone to track on a more southeastward direction. As TC 13S tracks further poleward, the strong VWS is expected to gradually erode the system. By TAU 36, the cyclone will commence extra-tropical transition as it gets embedded in the baroclinic zone, becoming a gale-force cold core low by TAU 48.

The available numerical guidance is in tight agreement with WBAR on the left of and UKMET on the right of the model envelope. There is high confidence in the JTWC forecast that is laid just to the left of and slightly faster than consensus. Maximum significant wave height is 30 feet.

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February 3rd, 2013 Category: Tropical Cyclones

Tropical Cyclone Felleng (13S) – February 2nd, 2013

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Track of TC 13S

Tropical Cyclone Felleng (13S), located approximately 370 nm southwest of La Reunion, has tracked southward at 14 knots over the past six hours.

Animated multispectral satellite imagery shows the system has begun to show signs of elongation as the main convective bands are displaced eastward of the low level circulation center. This is also readily apparent on a 37ghz SSMIS microwave pass.

The initial position is based on the above animation and on the SSMIS image with high confidence. The initial intensity is based on congruent Dvorak estimates from PGTW, KNES, and FMEE. Upper level analysis indicates the system is south and west of a ridge axis in an area of moderate to strong (20-30 knot) westerly vertical wind shear (VWS).

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