wdpn31 pgtw 051500 msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc// subj/prognostic reasoning for tropical depression 07w warning nr02// rmks/ 1. For meteorologists. 2. 12 hour summary and analysis. A. Tropical Storm (TS) 07w (Pabuk) has undergone considerable development over the past 12 hours. The low level circulation center (LLCC) has consolidated under the main convection with convergent bands wrapping in from the southeastern quadrant. Animated multi- spectral and enhanced infrared satellite imagery show the LLCC under the central convection, while a 050423z AMSU microwave image reveals convection flaring on the southern periphery of the LLCC. Ts 07w has tracked northwestward at 11 knots over the past 06 hours. B. Ts 07w is located approximately 510 nm southeast of Naha, Okinawa. Current position is based on a close grouping of Dvorak fixes. Current intensity is based on Dvorak intensity estimates of 45 knots. Ts 07w is tracking along the southwestern periphery of the subtropical ridge (str) east of Japan. Upper level analysis shows the presence of weak, but developing, outflow channels in both poleward and equatorward directions. 3. Forecast reasoning. A. Ts 07w is in the Standard synoptic pattern, tropical easterlies synoptic region. B. Orientation of the str is expected to remain largely zonal through tau 48, resulting in a west-northwestward track through tau 48. An approaching midlatitude trough is expected to weaken the str near tau 72, inducing a slight poleward turn. Ts 07w is expected to intensify at a climatologic rate in the early period, with a greater intensification rate anticipated as the outflow channels become better established. C. After tau 72, the str builds back in over the coast of China, causing a more northwestward track as the storm enters the poleward flow synoptic region and continues to track into Mainland China. The available dynamic aids are in good agreement with this scenario. However, some uncertainty exists regarding passage of ts 07w to the north of Taiwan, or landfall on Taiwan near tau 72. This forecast is based on a consensus of the available dynamic aids and crosses Taiwan between tau 48 and tau 72. After tau 72 the forecast track is based on the NOGAPS solution as the javi tracker loses the circulation near tau 72. Forecast team: Charlie//