msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc// subj/prognostic reasoning for typhoon 24w warning nr 16// rmks/ 1. For meteorologists. 2. 12 hour summary and analysis. A. Typhoon (TY) 24w (Mitag) has tracked slowly west-northwestward in a weak steering environment over the past 12 hours. TY 24w has maintained its intensity in this environment with improving poleward outflow and high ocean heat content balancing the negative influences of land interactions (with luzon) and impingment of subsiding air from a decaying tropical upper tropospheric trough cell to the east. B. The current storm position is based on satellite fixes from pgtw and rjtd. Dvorak T-numbers of 4.5/5.0 from pgtw, and 5.0/5.0 from knes and rjtd and a 240000z CIRA multiplatform wind estimate of 100 knots yield a current intensity estimate of 95 knots. Animated water vapor satellite imagery reveals favorable poleward and westward outflow. However, the decaying tropical upper tropospheric trough cell to the east of the system has begun to impinge on the eastern side of the outflow layer, introducing both upper level inflow and a slight increase in vertical wind shear. 3. Forecast reasoning a. The forecast reasoning has changed significantly since the previous issue of the prognostic reasoning bulletin. The avail- able dynamic aids are now in fair agreement indicating a recurvature scenario, and this forecast reflects that change. B. The subtropical ridge to the north is now the dominant steering influence, inducing a west-northwest to northwest track in the early forecast period. After tau 48 the system will reach the subtropical ridge and turn to the northeast. The current forecast antici- Pates landfall occurring just after tau 24. The system is expected to intensify as the TUTT cell to the east fills, poleward outflow remains strong, and moderate to high ocean heat content continues to fuel convective development. Significant weakening is anticipated as the system interacts with Luzon after landfall. The system should enter the South China Sea near tau 48. The system should maintain intensity as it tracks northward after tau 48 due to increased out- flow near the subtropical ridge axis. C. After tau 72 the system will track northeastward as it under- GOES extratropical transition. Interaction with an approaching mid- latitude trough, now located over central Asia extending southwest- Ward into the Northern Bay of Bengal, presents two possible alter- natives in the available dynamic aids. One alternative, represented by the NOGAPS-GFDN-JGSM grouping dissipates the system near tau 72 in the northern South China Sea. The second alternative, favored by this forecast, is represented by the grouping of EGRR-ecmf-tclp and GFS presents a recurvature scenario. Some uncertainty in the forecast is present, and depends on the timing and depth of the approaching midlatitude trough, and on the intensity of the system as it enters the South China Sea. A stronger system entering the South China Sea will be more survivable in the presence of the increased shear of the approaching midlatitude trough. A later arrival of the trough will also allow recurvature. Forecast team: Delta//