MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 25W (NAKRI) WARNING NR 03// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 25W (NAKRI), LOCATED APPROXIMATELY 281 NM WEST- SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED EAST-SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SOMEWHAT DISORGANIZED SYSTEM, WITH FLARING DEEP CONVECTION PRIMARILY CONFINED TO THE WESTERN PERIPHERY OF A BROAD, BUT CONSOLIDATING, LOW LEVEL CENTER. THE INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON THE ANIMATED MULTISPECTRAL IMAGERY, SUPPORTED BY A 060512Z ATMS 81 GHZ MICROWAVE IMAGE, WHICH SHOWED A WEAK LLC WITH DEEP CONVECTION TO THE WEST AND SOUTH. A WEAK SPINNER WAS EVIDENT IN ANIMATED MULTISPECTRAL IMAGERY TO THE EAST OF THE ASSESSED POSITION, BUT THIS WEAK VORTEX WAS EMBEDDED IN THE GENERAL SOUTHEASTERLY FLOW TO THE EAST OF THE LLC AND IS NOT REPRESENTATIVE OF THE ACTUAL CENTER OF THE SYSTEM. THE INITIAL INTENSITY HAS BEEN INCREASED TO 35 KTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 (35 KTS) FROM KNES, PGTW, AND RJTD SUPPORTED BY A SATELLITE CONSENSUS ESTIMATE OF 37 KNOTS. THE SYSTEM LIES IN A WEAKLY SUPPORTIVE ENVIRONMENT WITH THE SINGLE OUTFLOW CHANNEL BEING TO THE WEST, LOW (15-20 KNOTS) VWS AND HIGH SSTS AROUND 29 CELSIUS. WHILE VWS AND SSTS ARE VERY SUPPORTIVE FOR DEVELOPMENT, THE EASTERLY WINDS OVER TOP OF THE SYSTEM ARE PUSHING THE DEEP CONVECTION TOWARDS THE WEST, OFF OF THE LLC, CONTRIBUTING TO THE SLOW OVERALL DEVELOPMENT OVER THE PAST SIX HOURS. TS 25W IS MOVING VERY SLOWLY EAST-SOUTHEASTWARD IN A WEAK STEERING ENVIRONMENT. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 25W IS FORECAST TO DRIFT SLOWLY EAST TO EAST-NORTHEASTWARD OVER THE NEXT 24 HOUR WITH THE SYSTEM TRAPPED IN A COL REGION BETWEEN THE NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTH, AND TWO WEAK SUBTROPICAL RIDGES (STR) TO THE EAST AND WEST. AROUND TAU 36, STRONG WARM AIR ADVECTION FROM THE REMNANTS OF TS 23W IN THE BAY OF BENGAL WILL BUILD THE STR OVER NORTHWEST LAOS EXTENDING INTO THE NORTHERN SOUTH CHINA SEA. AT THIS POINT, THE STR BECOMES THE DOMINATE STEERING MECHANISM, LEADING TS 25W TO TURN FIRST SOUTHWARD, THEN WESTWARD BY TAU 36. THEREAFTER THE SYSTEM WILL ACCELERATE WESTWARD TOWARDS THE COAST OF VIETNAM THROUGH TAU 72. THE SYSTEM IS EXPECTED TO GRADUALLY INTENSIFY TO A PEAK OF 50 KTS AT TAU 36 DUE TO A COMBINATION OF HIGH SSTS AND LOW TO MODERATE VWS, OFFSET BY RELATIVELY STRONG WESTWARD OUTFLOW, LIMITING THE INTENSIFICATION POTENTIAL. THERE IS VERY HIGH UNCERTAINTY IN THE FIRST 36 HOURS OF THE FORECAST, WITH TWO DIVERGENT MODEL CLUSTERS. THE HWRF, NAVGEM, AND GFS SOLUTION MOVES THE SYSTEM SOUTHWARD THROUGH TAU 24 BEFORE TURNING WESTWARD. THE ALTERNATIVE SOLUTION FAVORED BY THE ECMWF, ECMWF ENSEMBLE, JGSM, EGRR AND THE GFS ENSEMBLE CONTINUES THE CURRENT EAST-NORTHEAST MOTION THROUGH TAU 24 BEFORE TURNING WEST. HOWEVER, ALL MODELS AGREE ON A VERY SLOW, MEANDERING MOTION DURING THIS TIMEFRAME, AND ALL AGREE ON THE EVENTUAL TURN TO THE WEST AND TRACK AGREEMENT IS SURPRISINGLY ROBUST BY TAU 72, WITH ONLY 60NM SPREAD IN ALL MODELS. THE JTWC FORECAST TRACK FAVORS THE NORTHERN CLUSTER OF MODELS AND IS PLACED NEAR THE MULTIMODEL CONSENSUS, WITH LOW CONFIDENCE. C. AFTER TAU 72, ALL MODELS AGREE ON A WESTWARD TRACK TOWARDS VIETNAM. TS 25W IS FORECAST TO MAKE LANDFALL ALONG THE VIETNAM COASTLINE SHORTLY AFTER TAU 96. JUST PRIOR TO LANDFALL, A DECREASE IN SST AND OHC VALUES, COMBINED WITH UPPER LEVEL CONVERGENCE FROM AN INVERTED TROUGH WILL RESULT IN AN OVERALL WEAKENING OF THE SYSTEM BEFORE LANDFALL. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY DISSIPATE OVER THE MOUNTAINOUS TERRAIN OF WESTERN VIETNAM. THERE IS OVERALL HIGH CONFIDENCE IN THIS PORTION OF THE TRACK, AS ALL MODELS ARE IN AGREEMENT WITH THE WESTWARD TRACK. THOUGH THE ECMWF SOLUTION HAS SHIFTED WELL TO THE SOUTH OVER THE PREVIOUS RUN, THE REMAINDER OF MODEL SOLUTIONS REMAIN IN TIGHT AGREEMENT.// NNNN NNNN