MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (NANGKA) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (NANGKA), LOCATED APPROXIMATELY 136 NM EAST- SOUTHEAST OF ENEWETAK, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON MICROWAVE IMAGERY AND ASCAT SCATTEROMETER DATA FROM A 042311Z METOP-B PASS. THE CURRENT INTENSITY OF 50 KNOTS IS CONSISTENT WITH THE AFOREMENTIONED ASCAT PASS AND DVORAK SATELLITE INTENSITY ESTIMATES FROM MULTIPLE REPORTING AGENCIES. RECENT MULTISPECTRAL SATELLITE IMAGERY SHOWS A TIGHTLY-WRAPPED LOW LEVEL CIRCULATION WITH LIMITED DEEP CONVECTION FLARING TO THE NORTH AND EAST OF THE CENTER. TS 11W LIES IN AN AREA OF LOW VERTICAL WIND SHEAR AND IMPROVING UPPER LEVEL OUTFLOW. THE SYSTEM IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO MAJOR CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 11W WILL CONTINUE TRACKING ALONG THE PERIPHERY OF THE CURRENT SUBTROPICAL STEERING RIDGE THROUGH THE NEXT 72 HOURS, TURNING GRADUALLY NORTHWESTWARD FROM ITS CURRENT WESTWARD TRACK AS THE STEERING RIDGE REORIENTS. LOW VERTICAL WIND SHEAR, INCREASING RADIAL OUTFLOW, AND PASSAGE OVER VERY WARM WATER WILL ALLOW THE SYSTEM TO STEADILY INTENSIFY DURING THIS PERIOD. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT REGARDING THE FORECAST TRACK THROUGH TAU 72. THE CURRENT TRACK FORECAST LIES CLOSE TO THE MULTI-MODEL CONSENSUS DURING THIS PERIOD. C. IN THE TAU 96 THROUGH TAU 120 PERIOD, TS 11W IS EXPECTED TO CONTINUE TRACKING GENERALLY NORTHWESTWARD ALONG THE SUBTROPICAL RIDGE PERIPHERY. INTENSIFICATION SHOULD CONTINUE AS ENVIRONMENTAL CONDITIONS REMAIN MOSTLY FAVORABLE, ALTHOUGH RESTRICTED POLEWARD OUTFLOW MAY LIMIT THE INTENSIFICATION RATE AS REFLECTED IN THE CURRENT FORECAST. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT IN THE EXTENDED RANGE, LENDING HIGH CONFIDENCE TO THE CURRENT TRACK FORECAST.// NNNN NNNN