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Forecast Change: Jasper Now Expected to Change Direction, Weaken

March 25th, 2009 Category: Tropical Cyclones

Track of Tropical Cyclone 23P (Jasper) - March 25th, 2009 © Univ. of Wisconsin

Track of Tropical Cyclone 23P (Jasper) - March 25th, 2009


TC 23P

Tropical Cyclone 23P (Jasper), located approximately 205 nautical miles west-northwest of Noumea, New Caledonia, has tracked southeastward at 12 knots over the past six hours. Maximum significant wave height is 12 feet.

Observation of an exposed low level circulation center (LLCC) in recent animated multispectral satellite imagery lends confidence to the initial position. The current intensity estimate is consistent with recent agency Dvorak t-numbers ranging from 2.0 to 3.0.

The forecast philosophy for TC 23P has changed significantly since the previous warning. Increasing northwesterly vertical wind shear has displaced nearly all deep convection associated with this cyclone well to the southeast of the LLCC. The steering level for the storm has lowered as a consequence of this shear and a resultant ongoing weakening trend.

Therefore, the storm is now expected to follow strong southeasterly low to mid-level flow analyzed to the southwest. This southeasterly flow will begin to steer the LLCC equatorward by TAU 12.

As the storm turns equatorward, persistent vertical wind shear will offset the favorable influences of strong poleward outflow and warm sea surface temperatures, causing the system to weaken below the 35 knot warning threshold by TAU 36.

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