msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc// subj/prognostic reasoning for tropical storm 23w (hagibis)warning nr 10// rmks/ 1. For meteorologists. 2. 12 hour summary and analysis. A. Tropical Storm (TS) 23w has intensified over the past 12 hours as the storm remains in the diffluent southwestern quadrant of the upper level (200 mb) ridge to the east-northeast. A 210023z SSMI/S microwave image reveals an improving low level circulation center west of palawan. The system has increased speed as it re-consolidates and moves into a more favorable environment over the South China Sea. B. The current intensity is based on satellite estimates of 55 knots from pgtw and a 210000z CIRA multiplatform maximum wind speed estimate of 44 knots and a 210000z surface observation from nansha dao (~10.4n 114.4e) of 40 knots. The system remains over high sea sur- face temperatures but is experiencing moderate vertical wind shear as it moves out over the South China Sea. 3. Forecast reasoning. A. The forecast track has remained consistent since the last reaso- ning, however the storm has increased speed in the 12 hour period due to a re-consolidation of the low level circulation center after moving west of palawan. Ts 23w is expected to slow dramatically as it approa- ches landfall near tau 48 and dissipate over southeastern Vietnam by tau 96. B. Ts 23w is expected to continue generally westward through the forecast period under the steering influence of a continuous subtro- pical ridging to the north of the storm. As the system moves west over the South China Sea during the next 12 hours, favorable upper level outflow and high ocean heat content are expected to balance the nega- tive influence of moderate vertical wind shear and permit a modest intensification through tau 24. Forecast aids are in good agreement with a westward track through the South China Sea through tau 48. C. In the extended period, available forecast aids diverge signif- icantly after tau 48. NOGAPS and GFDN carry the system on a westward track, however EGRR and AVN represent an extreme departure from pre- vious dynamic aids packages by depicting a recurvature scenario due to an eastward moving mid-level trough near tau 48. This forecast favors the NOGAPS solution, which calls for ts 23w to slow and weaken between 48 and 72 hours as the system interacts with land (vietnam) and begins to entrain relatively drier/more stable air. The weakening circulation is expected to dissipate over southeastern Vietnam near tau 96. Forecast team: Delta//