MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 30W (THIRTY) WARNING NR 02// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 30W (THIRTY), LOCATED APPROXIMATELY 122 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. DESPITE TRACKING OVER THE CENTRAL PHILIPPINE ISLANDS, ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTIVE BANDING WRAPPING INTO THE LLCC. A 090630Z SSMI 85GHZ IMAGE INDICATES THAT THE BULK OF THE DEEP CONVECTION IS LOCATED OVER THE NORTHERN SEMI-CIRCLE, HOWEVER, CONVECTIVE ORGANIZATION IS IMPROVING WITH A DEFINED CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND NEAR-RADIAL OUTFLOW. THE INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM T1.5 TO T2.0 (25 TO 30 KNOTS). TD 30W IS TRACKING QUICKLY ALONG THE SOUTHERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE DEEP-LAYERED STR THROUGH TAU 72. THE SYSTEM IS EXPECTED TO INTENSIFY SIGNIFICANTLY AFTER TRACKING OVER THE SOUTH CHINA SEA AFTER TAU 12 WITH FAVORABLE ENVIRONMENTAL CONDITIONS PERSISTING. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT WITH A 100-NM SPREAD IN SOLUTIONS AT TAU 72. C. AFTER TAU 72, DYNAMIC GUIDANCE SPLITS INTO TWO DISTINCT GROUPS WITH INCREASING UNCERTAINTY IN THE FORECAST TRACK. THE FIRST GROUP (AFUM, UKMO, HWRF, NVGM, ECMF AND EEMN) WEAKEN THE SYSTEM RAPIDLY AND TRACK THE REMNANTS SOUTHWESTWARD TO WEST-SOUTHWESTWARD. THE SECOND GROUP (AEMN, AVNO, CTCX AND UEMN) DEPICT A SLOW POLEWARD TRACK. IN GENERAL, THE MODEL FIELDS INDICATE INCREASING WESTERLY FLOW ACROSS SOUTHEAST CHINA AFTER TAU 72, WHICH WILL SERVE TO WEAKEN THE STR AND LEAD TO A SIGNIFICANT TRACK SLOW-DOWN. THE JTWC FORECAST TRACK FAVORS A SLOW POLEWARD MOTION OVER HAINAN ISLAND AS THE SYSTEM ENCOUNTERS WESTERLY FLOW AND TRACKS ALONG THE WESTERN PERIPHERY OF THE STR. DUE TO THE INCREASING UNCERTAINTY IN THE TRACK FORECAST AFTER TAU 72, THERE IS LOW OVERALL CONFIDENCE IN THE JTWC FORECAST.// NNNN NNNN