WDPN31 PGTW 090300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (AERE) WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 22W (AERE), LOCATED APPROXIMATELY 174 NM EAST OF HONG KONG, HAS TRACKED NORTH-NORTHWESTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A DECAYING, EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FLARING DEEP CONVECTION OVER THE NORTHERN SEMI-CIRCLE OF THE LLCC. A 082319Z SSMIS 37GHZ IMAGE SHOWS SHALLOW BANDING WRAPPING LOOSELY INTO THE BROAD CENTER WITH ISOLATED CONVECTION OVER THE NORTH QUADRANT. DUE TO THE BROAD NATURE OF THE CENTER, THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK MOTION, WHICH APPEARS TO BE QUASI- STATIONARY IN NATURE. THE CURRENT INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM 30 TO 35 KNOTS. UPPER-LEVEL ANALYSIS SHOWS A MARGINALLY-FAVORABLE ENVIRONMENT WITH SOUTHERLY VERTICAL WIND SHEAR OFFSET BY POLEWARD OUTFLOW AND LOW OCEAN HEAT CONTENT VALUES. TS 22W IS TRACKING QUASI-STATIONARY WITHIN A WEAK STEERING ENVIRONMENT. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS AERE WILL REMAIN IN A WEAK STEERING ENVIRONMENT OVER THE NEXT 12 HOURS EXHIBITING QUASI-STATIONARY TRACK MOVEMENT UNTIL A LOW- LEVEL RIDGE BUILDS TO THE NORTH. THIS RIDGE IS ASSOCIATED WITH A MODERATE NORTHEAST SURGE, WHICH IS EXPECTED TO ENHANCE WIND FLOW THROUGH THE TAIWAN STRAIT AND ADVECT COOLER, DRIER AIR INTO THE NORTHERN SOUTH CHINA SEA. THE OVERALL EFFECT WILL BE TO DRIVE TS 22W SOUTHWESTWARD WHILE SIGNIFICANTLY WEAKENING THE SYSTEM. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE BULK OF THE VORTEX TRACKERS INDICATING A SOUTHWESTWARD TRACK TOWARD HAINAN ISLAND. THE SYSTEM IS EXPECTED TO DISSIPATE OVER WATER BY TAU 48. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE TIMING OF THE TRACK CHANGE AND SIGNIFICANT DIFFERENCES IN TRACK SPEED AFTER TAU 24.//