MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (LINFA) WARNING NR 21// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 10W (LINFA), LOCATED APPROXIMATELY 287 NM EAST-SOUTHEAST OF HONG KONG, HAS TRACKED NORTH-NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS SLIGHTLY DEEPENED EVEN AS THE ASSOCIATED DEEP CONVECTION IS PARTIALLY SHEARED SOUTHWESTWARD. THE INITIAL POSITION IS BASED ON THE IR LOOP AND EXTRAPOLATED FROM THE RAGGED LLCC FEATURE IN THE 062309Z 91GHZ SSMIS MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 40 KNOTS IS BASED ON THE DVORAK ESTIMATE FROM PGTW. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH LIGHT TO MODERATE (10-15 KNOT) NORTHEASTERLY VWS PARTIALLY OFFSET BY GOOD EQUATORWARD OUTFLOW. ADDITIONALLY, A TROUGH IS SUPPRESSING CONVECTION ALONG THE NORTHERN FLANK OF THE SYSTEM. THESE ARE EVIDENT ON ANIMATED WATER VAPOR SATELLITE IMAGERY. THE CYCLONE IS CURRENTLY TRACKING UNDER THE STEERING INFLUENCE OF THE LOW- TO MID-LEVEL STR TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 10W WILL CONTINUE TO TRACK SLOWLY NORTHWARD UNDER THE INFLUENCE OF THE STEERING STR. MARGINAL CONDITIONS ARE EXPECTED TO LIMIT INTENSIFICATION WITH A PEAK INTENSITY OF 55 KNOTS NEAR TAU 36 AS VWS ABATES SLIGHTLY. AFTERWARDS, THE CYCLONE IS EXPECTED TO TURN NORTHWESTWARD THEN WESTWARD AS THE STR BUILDS. CONCURRENTLY, GRADUAL WEAKENING IS FORECAST WITH DISSIPATION BY TAU 72 OVER LAND. THE OVERALL JTWC FORECAST CONFIDENCE LEVEL REMAINS LOW DUE TO THE COMPLEX STEERING ENVIRONMENT AND POSSIBLE WEAK DIRECT CYCLONE INTERACTION WITH TY 09W NEAR TAU 72.// NNNN NNNN