MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (NANGKA) WARNING NR 43// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 11W (NANGKA), LOCATED APPROXIMATELY 290 NM WEST- SOUTHWEST OF IWO TO, HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. RECENT MSI DEPICTS SPIRAL BANDS TIGHTLY WRAPPING INTO A CLOUD-FILLED EYE. ADDITIONALLY, THE MSI CONTINUES TO SHOW THINNING CONVECTION ON THE NORTHERN SEMI-CIRCLE. THE CURRENT POSITION IS BASED ON THE MSI AND CORRESPONDING SATELLITE FIXES FROM PGTW AND RJTD WITH HIGH CONFIDENCE. THE CURRENT INTENSITY REMAINS 95 KNOTS BASED ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN AN AREA OF LOW TO MODERATE (10 TO 15 KNOT) VWS WITH RADIAL OUTFLOW AS EVIDENT ON THE WATER VAPOR IMAGERY. THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN SIDE OF THE STEERING STR. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 11W WILL CONTINUE TO TRACK POLEWARD AS THE STEERING STR BACKS TO THE EAST. BY TAU 48, THE STEERING STR IS EXPECTED TO REBUILD, FORCING TY NANGKA WEST-NORTHWESTWARD. FAVORABLE CONDITIONS WILL PERSIST; HOWEVER, THE NORTHERN SEMI-CIRCLE WILL BE IMPACTED BY THE HIGH PRESSURE TO THE NORTH. THEREFORE, TY NANGKA IS EXPECTED TO STEADILY INTENSIFY OVER THE NEXT 48 HOURS. AFTERWARD INCREASING VWS AND DECREASING ENVIRONMENTAL CONDITIONS WILL BEGIN TO WEAKEN THE SYSTEM AS IT APPROACHES THE SOUTHERN COAST OF JAPAN. C. BY TAU 72, TY NANGKA IS EXPECTED TO TRACK OVER THE SOUTHERN ISLANDS OF JAPAN. TY 11W WILL ROUND THE RIDGE AXIS AND TRACK NORTHEASTWARD ALONG THE NORTHWESTERN EDGE OF THE STEERING STR. MODEL GUIDANCE CONTINUES TO SHOW A SIGNIFICANT SPREAD AT TAU 72. DUE TO THE UNCERTAINTY IN THE EXTENT OF THE STR AND DIFFERENCES IN THE TRACK SPEEDS, THE OVERALL JTWC FORECAST REMAINS LOW.// NNNN NNNN