WDPN31 PGTW 040300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (NOUL) WARNING NR 05// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 06W (NOUL), LOCATED APPROXIMATELY 131 NM EAST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CURVED BANDING WRAPPING INTO A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER , WITH DEEP CONVECTION IN THE NORTHERN AND WESTERN QUADRANTS. THE CURRENT POSITION IS BASED ON MSI AND FIXES FROM PGTW AND RJTD, AND IS FURTHER SUPPORTED BY A 032210Z SSMIS 37 GHZ MICROWAVE PASS WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 FROM ALL AGENCIES. THE FORWARD MOTION HAS SLOWED IN RESPONSE TO A WEAKNESS IN THE SUBTROPICAL RIDGE (STR) TO THE NORTH. UPPER LEVEL ANALYSIS INDICATES THE ENVIRONMENT HAS BECOME SLIGHTLY LESS FAVORABLE, WITH THE EFFECTS OF INCREASED (15 KNOTS) SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) EVIDENT IN THE MSI. POLEWARD OUTFLOW HAS ALSO WANED SLIGHTLY. SEA SURFACE TEMPERATURES REMAIN FAVORABLE AT 28- 29 DEGREES CELSIUS. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS WARNING. B. TS 06W IS EXPECTED TO SLOWLY TRACK WESTWARD OVER THE NEXT 36-48 HOURS WHILE THE WEAKENED STR TO THE NORTH GRADUALLY REBUILDS. BY TAU 48, FORWARD MOTION SHOULD INCREASE AND RESUME A WEST- NORTHWESTWARD TRACK ALONG THE SOUTHERN PERIPHERY OF THE STEERING RIDGE. VWS AND UPPER-LEVEL OUTFLOW ARE EXPECTED TO BE GENERALLY FAVORABLE DURING THIS PORTION OF THE FORECAST, ENABLING NOUL TO STEADILY INTENSIFY AT A NEAR CLIMATOLOGICAL RATE. UNCERTAINLY AMONG THE NUMERICAL GUIDANCE AIDS IS HIGH, WITH TRACK SOLUTIONS HIGHLY DEPENDENT ON THE STRENGTH OF THE STR DEPICTED BY THE MODEL. GFDN, COTC, NVGM, AND ECMWF ALL DRIVE THE SYSTEM EQUATORWARD OVER THE NEXT 36 HOURS, WHILE REMAINING MODELS MAINTAIN A NORTHWESTWARD TRACK. DUE TO THE LARGE MODEL SPREAD, THE NEAR-TERM JTWC FORECAST IS PLACED SLIGHTLY NORTH OF THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE. C. IN THE EXTENDED TAUS, TS 06W WILL TRACK STEADILY NORTHWESTWARD UNDER THE STEERING INFLUENCE OF A BUILDING STR. THE SYSTEM SHOULD CONTINUE TO INTENSIFY GIVEN FAVORABLE ENVIRONMENTAL INFLUENCES. NUMERIC MODEL GUIDANCE IS BIFURCATED, AS DIFFERENCES IN MODEL DEPICTION OF THE STR RESULT IN EITHER A STRAIGHT-RUNNING OR A RECURVING TRACK. OVER THE PAST CYCLE, THE HWRF SOLUTION CHANGED DRASTICALLY, CALLING FOR A PEAK OF ONLY 55 KNOTS AND PRONOUCED SOUTHWARD SHIFT IN TRACK. THE GFS AND GEFS MAINTAIN A STRONGER VORTEX THAT STARTS TO ROUND THE STR AT THE END OF THE FORECAST PERIOD. THE FORECAST IS PLACED CLOSE TO THE CONSENSUS MEAN TRACK, AND ADJUSTED SLIGHTLY TO ACCOUNT FOR EXTREME SOUTHERN OUTLIERS (GFDN AND COTC). BASED ON THE LARGE GUIDANCE SPREAD, CONFIDENCE IN THE JTWC 96 AND 120 HOUR FORECAST POSITIONS IS LOW.// NNNN