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Tropical Cyclone Oli (12P) Moves South and Weakens

26.6S 142W

February 6th, 2010 Category: Tropical Storms

Tropical Cyclone Oli (12P) - February 5th, 2010

Tropical Cyclone Oli (12P) - February 5th, 2010

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Track of TC 12P - February 5th, 2010 © Univ. of Wisconsin

Track of TC 12P

Tropical Cyclone Oli (12P), located approximately 295 nautical miles south of Tahiti, has tracked southeastward at 15 knots over the past six hours. Maximum significant wave height is 20 feet.

The cyclone has begun to weaken and accelerate poleward since the previous forecast. Both PGTW and PHFO have dropped their current intensity estimates half a T-number to 5.5 or 102 knots since the previous synoptic hour. The southern eye wall has begun to erode as the southernmost convection is sheared into the mid-latitude flow, leaving the eye ragged and irregular.

The cyclone will continue to transit along the southwestern periphery of the deep-layer subtropical ridge to the east while steadily weakening due to increased vertical wind shear and unfavorable sea surface temperatures/oceanic heat. The cyclone will begin to interact with a baroclinic boundary near TAU 36 and will transition to a fully extratropical system by TAU 48. Model guidance remains in relatively good agreement with the exception of the eastern outlier, TCLAPS.

Tropical Cyclone Oli (12P) Located Southwest of Tahiti

14.7S 148.3W

February 5th, 2010 Category: Tropical Storms

Tropical Cyclone Oli (12P) - February 4th, 2010

Tropical Cyclone Oli (12P) - February 4th, 2010

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Track of TC 12P - February 5th, 2010 © Univ. of Wisconsin

Track of TC 12P

Tropical Cyclone Oli (12P), located approximately 185 nautical miles southwest of Tahiti, has tracked southeastward at 12 knots over the past six hours. Maximum significant wave height is 23 feet.

Animated multispectral satellite imagery indicates a 17 nautical mile eye with deep convection decreasing in areal extent. This is evident in a an AMSU 89 GHZ microwave image which shows a symmetric eye wall with tightly curved convective banding wrapping into the center with slight erosion of deep convection over the southwest quadrant.

Water vapor imagery indicates that the system has good radial outflow, with enhanced poleward outflow associated with a midlatitude trough south of the system.

TC 12P has maintained an intensity of 115 knots over the past 12 hours with current Dvorak estimates of 102 to 115 knots. Upper level analysis indicates that the system is located in a favorable environment with weak vertical wind shear and an enhanced poleward outflow channel.

Oli is currently tracking southeastward along the southwestern periphery of the sub-tropical ridge. The system is forecast to accelerate and continue tracking southeastward as it interacts with the baroclinic zone and begins extra-tropical transition (ETT) near TAU 36. By TAU 72, TC 12P is expected to complete ETT. Numerical guidance is in good agreement with this forecast, with the exception of TCLAPS, which rapidly decreases the intensity and tracks the system south-southwest.

Tropical Cyclone Formation Alert in Pacific Ocean, West of Tahiti

March 10th, 2009 Category: Tropical Cyclones

Tropical cyclone formation - March 10th, 2009 © JTWC

Tropical cyclone formation - March 10th, 2009

Formation of a significant tropical cyclone is possible within 160 nm either side of a line from 18.3S 155.7wW to 20.6S 161.5W within the next 12 to 24 hours, although available data does not justify issuance of numbered tropical cyclone warnings at this time.

Winds in the area are estimated to be 25 to 30 knots. METSAT imagery indicates that a circulation center is located near 18.7S 156.4W.  The system is moving west-southwestward at 4 knots.

An area of convection has persisted approximately 415 nm west of Tahiti.

Recent animated multispectral imagery shows a well-defined low level circulation center (LLCC) with formative convective banding wrapping into the center.

This LLCC is confirmed by a QUIKSCAT pass showing winds of 25 to 30 knots near the center.

An anti-cylcone aloft, and weak upper-level troughing to the southeast of the disturbance, are providing ample outflow for development.

The system lies in a region of weak to moderate vertical wind shear, warm SST (great than 26c) and significant ocean heat content.

Maximum sustained surface winds are estimated at 25 to 30 knots. Minimum sea level pressure is estimated to be near 1001 mb.

Due to the favorable surface conditon as well as good conditions aloft, the potential for the development of a significant tropical cyclone within the next 24 hours is good.