WDPN31 PGTW 130300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (UTOR) WARNING NR 18// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 11W (UTOR), LOCATED APPROXIMATELY 236 NM SOUTH- SOUTHEASTWARD OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS MULTIPLE WELL-DEVELOPED DEEP CONVECTIVE BANDS SPIRALING INTO A WELL-DEFINED EYE. A 130029Z SSMIS MICROWAVE IMAGE FURTHER REVEALS THE DEEP CONVECTIVE BANDING STRUCTURE AS WELL AS A TIGHT AND CONSOLIDATED EYE FEATURE. THE CURRENT POSITION IS BASED ON THE MSI AS WELL AS THE PGTW SATELLITE FIX WITH HIGH CONFIDENCE. THE CURRENT INTENSITY OF 100 KNOTS IS CONSISTENT WITH THE DVORAK T- NUMBER ESTIMATE FROM PGTW. UPPER-LEVEL ANALYSIS INDICATES TY 11W LIES SLIGHTLY EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK (5 TO 10 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) AND EXCELLENT EQUATORWARD OUTFLOW. TY 11W CONTINUES TO TRACK WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL STEERING RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TY 11W WILL CONTINUE TRACKING WEST-NORTHWESTWARD OVER THE NEXT 12 HOURS UNDER THE STEERING INFLUENCE OF THE STR. THE SYSTEM WILL TURN SLIGHTLY MORE POLEWARD AFTER TAU 12 AS IT ENCOUNTERS A WEAKNESS IN THE STR INDUCED BY A SHORTWAVE TROUGH PASSING FAR TO THE NORTH. TY 11W IS EXPECTED TO MOVE INLAND NEAR ZHANJIANG, CHINA JUST PRIOR TO TAU 36. AFTER TAU 36, THE CYCLONE SHOULD TURN WESTWARD UNDER THE INFLUENCE OF THE REBUILDING STR AND BEGIN DISSIPATING OVER LAND. INTENSIFICATION THROUGH TAU 24 IS EXPECTED AS UPPER-LEVEL DIFFLUENCE REMAINS FAVORABLE. ADDITIONALLY, THE CHANCE REMAINS FOR THE SYSTEM TO INTENSIFY MORE THAN CURRENTLY FORECAST PENDING THE DEVELOPMENT OF THE AFOREMENTIONED WEAKNESS IN THE STR AND INTERACTION WITH AN UPPER- LEVEL LOW ANALYZED OVER SOUTHERN CHINA. THE UPPER-LEVEL LOW HAS THE POTENTIAL TO DEVELOP A SUBSTANTIAL POLEWARD OUTFLOW CHANNEL AND AID IN INTENSIFICATION. GIVEN THE GOOD AGREEMENT WITH THE NUMERICAL MODEL GUIDANCE, CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72 REMAINS HIGH. C. TY 11W WILL DISSIPATE OVER LAND IN THE EXTENDED PERIOD, DROPPING BELOW THE WARNING THRESHOLD INTENSITY OF 25 KNOTS BY TAU 96. THE JTWC FORECAST TRACK IS IN GOOD AGREEMENT WITH THE NUMERICAL MODEL GUIDANCE, WITH THE EXCEPTION OF THE EASTWARD-OUTLYING JGSM AND THE JAPANESE ENSEMBLE, THUS, CONFIDENCE IN THE FORECAST TRACK REMAINS HIGH.// NNNN