MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (NANGKA) WARNING NR 03// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (NANGKA), LOCATED APPROXIMATELY 130 NM EAST- NORTHEAST OF KWAJALEIN, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A TIGHTLY WRAPPED SYSTEM WITH SEVERAL CONVECTIVE BANDS WRAPPING INTO THE SYSTEM CENTER. A SLOT OF DRY AIR IS ALSO EVIDENT TO THE WEST OF TS NANGKA WHICH APPEARS TO BE LIMITING CONVECTIVE GROWTH ACROSS THE CORRESPONDING QUADRANT OF THE SYSTEM. A 032238Z METOP-A MICROWAVE IMAGE REVEALS THE LLCC WHICH IS OBSCURED BY CONVECTION IN THE MSI AS WELL AS VERIFIES THE DRY AIR SLOT TO THE WEST OF THE SYSTEM. THE INITIAL POSITION IS BASED ON THE AFOREMENTIONED MICROWAVE IMAGE AND IN GOOD AGREEMENT WITH THE 00Z PGTW FIX POSITION. THE INITIAL INTENSITY IS ASSESSED AT 40 KTS BASED ON THE 032151Z ASCAT IMAGE WHICH SHOWS 40 KNOT WIND BARBS ACROSS THE NORTHERN SEMI-CIRCLE OF TS 11W. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH 5-15 KTS VERTICAL WIND SHEAR AND GOOD POLEWARD OUTFLOW. TS 11W IS CURRENTLY TRACKING WEST-NORTHWEST ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 11W IS EXPECTED TO CONTINUE TRACKING WEST-NORTHWEST ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH TAU 48. TRACK SPEEDS HAVE SLIGHTLY SLOWED FROM THE PREVIOUS WARNING, BUT ARE EXPECTED TO REMAIN STEADY THROUGH TAU 48. INTENSIFICATION MAY BE LIMITED OVER THE NEXT 12-24 HOURS AS A SLOT OF DRY AIR TO THE WEST OF THE SYSTEM IS ENTRAINED, HOWEVER, DUE TO THE STRONG MOISTURE TAP TO THE SOUTH AND EAST OF THE SYSTEM TS 11W IS EXPECTED TO OVERCOME THIS UNFAVORABLE POCKET OF AIR. STEADY INTENSIFICATION IS EXPECTED THEREAFTER DUE TO FAVORABLE UPPER LEVEL CONDITIONS AS WELL AS WARM SSTS AND POSITIVE OHC VALUES. AFTER TAU 48 NANGKA IS EXPECTED TO TURN SLIGHTLY MORE POLEWARD AND BEGIN TRACKING TO THE NORTHWEST. C. TS 11W IS EXPECTED TO CONTINUE ON THE NORTHWEST TRAJECTORY THROUGH TAU 120. STEADY INTENSIFICATION IS EXPECTED TO REACH A PEAK INTENSITY OF 90 KTS BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. HOWEVER, DUE TO THE DYNAMIC PATTERN CURRENTLY OBSERVED IN THE WESTERN PACIFIC, CLOSE ATTENTION SHOULD ALSO BE PAID TO THE EVOLUTION OF TS 09W AND THE TROUGH NORTH OF THE SYSTEM WHICH IS SLOWLY RETREATING POLEWARD.// NNNN NNNN