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Typhoon Lupit (22W) North of Philippines

17.9N 124.4E

October 22nd, 2009 Category: Tropical Cyclones

Typhoon Lupit Near Taiwan - October 22nd, 2009

Typhoon Lupit Near Taiwan - October 22nd, 2009

Track of Lupit - October 21st, 2009 © Univ. of Wisconsin

Track of Lupit

Enhanced image

Enhanced image

Typhoon 22W (Lupit), located approximately 370 nautical miles northeast of Manila, Philippines, has tracked west-southwestward at 6 knots over the past six hours. Maximum significant wave height is 31 feet.

Recent animated infrared imagery shows a strong system with tightly curved banding, deep convection over the low level circulation center (LLCC) and good radial outflow. An AMSR-E pass shows multiple deep convective bands wrapping into a well formed eye-like feature in the lower levels (37ghz). An upper level image (89ghz), however, shows the eye-like feature open on the northern side of the LLCC.

The system is moving into a region of weaker steering as it moves out of the periphery of the subtropical ridge (STR) to the northeast and is yet to come fully under the influence of the STR to the west. As a result of the system being in a weak steering environment, numerical guidance is in poor agreement as to the track of TY 22W.

Two very distinct scenarios exist for the track. The first scenario is for the system to continue slowly tracking to the west-southwest towards the northern tip of Luzon under the influence of a finger of the STR to the west. Under this scenario, around TAU 72, a short-wave midlatitude trough will pass through the area, erode the finger of the STR, and the system will become quasi stationary in the vicinity of the Strait of Luzon.

The second scenario, on the other hand, calls for the system to rapidly turn to the northeast between TAU 12 and 24 under the influence of a westerly surge from the northern side of the STR to the west. In this scenario, the system would then be picked up by the flow around the STR to the east and would then track into the midlatitude westerlies.

A thorough analysis of the deep layer mean flow around the STR to the west of the system indicates that Lupit is currently south of the STR axis, and it is unlikely to be affected by flow on the northern side of the STR. For this reason, the forecast favors the first scenario, but the second scenario remains plausible.

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