MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (PHANFONE) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 30W (PHANFONE), LOCATED APPROXIMATELY 384 NM EAST- SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY REVEALS AN INTERMITTENT EYE FEATURE PEEKING OUT WITHIN A COMPACT AREA OF SUSTAINED DEEP CENTRAL CONVECTION. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION, WHICH IS SUPPORTED BY A WELL-DEFINED MICROWAVE EYE IN A 240432Z AMSR-2 36GHZ IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 80 KTS, IN AGREEMENT WITH THE PGTW AND KNES DVORAK CURRENT INTENSITY ESTIMATES OF T4.5 (77 KTS) AND A 240510Z SATCON ESTIMATE OF 82 KTS. THE ENVIRONMENT IS FAVORABLE FOR CONTINUED DEVELOPMENT WITH LOW (10-15 KT) VERTICAL WIND SHEAR (VWS), GOOD POLEWARD AND EQUATORWARD OUTFLOW AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURES (SSTS). TY 30W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 30W WILL TRACK GENERALLY WEST-NORTHWESTWARD THROUGHOUT THE FORECAST. BETWEEN TAUS 12 AND 36, THE FAVORABLE ENVIRONMENT IS EXPECTED TO PARTIALLY OFFSET THE LAND INTERACTION, ALLOWING THE SYSTEM TO MAINTAIN INTENSITY AT 80 KTS. ONCE TY 30W EMERGES IN THE SOUTH CHINA SEA, IT WILL INTENSIFY TO A MAXIMUM OF 90 KTS AT TAU 48. DUE TO THE COMPLICATED NATURE OF THE LAND INTERACTION IN THIS FORECAST, THERE IS HIGH UNCERTAINTY IN THE INTENSITY FORECAST. HWRF, COAMPS-GFS, COAMPS-NAVGEM, AND ECMWF INTENSITY GUIDANCE IS SIGNIFICANTLY ABOVE THE MULTI-MODEL CONSENSUS AND AT THE TOP OF THE 70% PROBABILITY CURVE; HOWEVER, UKMET AND GFS ARE SIGNIFICANTLY BELOW THE CONSENSUS. DECAY SHIPS , GALWEM, AND NAVGEM ARE ROUGHLY IN LINE WITH THE INTENSITY CONSENSUS. THE JTWC INTENSITY FORECAST IS HEDGED SLIGHTLY ABOVE THE MULTI-MODEL CONSENSUS, TOWARDS HWRF, ECMWF, AND THE COAMPS SOLUTIONS, IN RECOGNITION OF THE FAVORABLE ENVIRONMENT AND EMERGING EYE. THERE IS STRONG AGREEMENT IN THE MODEL TRACK GUIDANCE THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. THE JTWC FORECAST TRACK IS HEDGED SLIGHTLY SOUTH OF THE MULTI-MODEL TRACK CONSENSUS TOWARDS THE ECMWF SOLUTION. C. AFTER TAU 72, TY 30W WILL BEGIN TO ENCOUNTER DECREASING SSTS (26-27 DEGREES CELSIUS), INCREASING VWS AND RELATIVELY COOL, DRY AIR FROM A BUILDING SURFACE HIGH PRESSURE SYSTEM TO THE NORTH. AS A RESULT, TY 30W WILL BEGIN A RAPID WEAKENING TREND. FURTHERMORE, THE SYSTEM WILL SLOW AS IT APPROACHES A COL BETWEEN THE STEERING STR AND A LESS PRONOUNCED STR TO THE WEST. MODEL GUIDANCE SPREADS SIGNIFICANTLY IN BOTH NORTH-SOUTH PLACEMENT AND ALONG TRACK SPEED AFTER TAU 72. ECMWF AND NAVGEM, WHICH MAINTAIN A MUCH HIGHER INTENSITY THROUGHOUT THE FORECAST PERIOD, AS WELL THE UKMET ENSEMBLE MEAN, CURVE THE SYSTEM SHARPLY TO THE NORTHWEST INTO THE AREA OF WEAK STEERING. HOWEVER, GFS CONTINUES NORTHWESTWARD, AND GALWEM AND UKMET CURVE THE SYSTEM WEST-SOUTHWESTWARD. THE JTWC FORECAST TRACK IS PLACED ALONG THE MULTI-MODEL CONSENSUS AFTER TAU 72 WITH LOW CONFIDENCE, PREDICATED ON THE REASONING THAT, AS TY 30W WEAKENS, IT WILL BECOME SUBJECT TO THE STEERING INFLUENCE OF THE LOWER LEVEL NORTHEASTERLY SURGE.// NNNN NNNN