Typhoon 09W(SAOLA) to reach CAT 4 US East of Luzon//TS 08W(DAMREY) intensifying /TS 08L(FRANKLIN) intensifying//Invest 92E//2609utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 08W(DAMREY) AND 09W(SAOLA).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM-SIZED, HIGHLY-SYMMETRICAL SYSTEM THAT HAS MOSTLY SUSTAINED ITS INTENSE CONVECTIVE STRUCTURE WITH THE ADDITION OF A 10-NM, SHARPLY OUTLINED EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 105KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SLIGHT 6-HR IMPROVEMENT. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH VERY WARM SST IN THE PHILIPPINE SEA, LOW VWS, AND MODERATE RADIAL OUTFLOW ALOFT.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY SAOLA WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STR TO THE WEST. AFTER TAU 12, A NEAR EQUATORIAL RIDGE TO THE SOUTH WILL ASSUME STEERING AND DRIVE THE CYCLONE EASTWARD. AROUND TAUS 36-48, A NORTH-SOUTH EXTENSION OF A SECONDARY DEEP-LAYER STR TO THE NORTHEAST WILL ASSUME STEERING AND DRIVE THE SYSTEM POLEWARD, THEN AROUND TAU 72, THIS SAME STR WILL BUILD AND ACCELERATE THE SYSTEM NORTHWESTWARD TOWARD TAIWAN VIA THE LUZON STRAIT. THE FAVORABLE ENVIRONMENT, TEMPERED ONLY BY LOCALIZED OCEAN UPWELLING, WILL PROMOTE FURTHER INTENSIFICATION TO A PEAK OF 120KTS BY TAU 36. AFTERWARD, INCREASED UPWELLING AND THE ONSET OF DRY AIR INTRUSION AT THE LOW LEVELS WILL GRADUALLY WEAKEN THE SYSTEM DOWN TO 90KTS BY TAU 120 AS IT REACHES THE TAIWAN STRAIT WHERE LAND INTERACTION AND INCREASING VWS BEGIN TO CONTRIBUTE TO THE CONVECTIVE EROSION OF SAOLA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT WITH THIS LOOPING TRACK FORECAST WITH A GRADUAL SPREAD TO 176NM AT TAU 72 THEN 295NM AT TAU 120. JGSM IS THE NOTABLE RIGHT-OF-TRACK OUTLIER AND GFS IS ON THE LEFT MARGIN OF THE MODEL ENVELOPE AFTER TAU 72. THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN ELONGATED BUT CONSOLIDATING SYSTEM WITH A PARTIALLY EXPOSED LOW LEVEL CIRCULATION THAT HAS MOSTLY MAINTAINED ITS OVERALL CONVECTIVE STRUCTURE AS IT ACCELERATES POLEWARD. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI LOOP. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES TO REFLECT THE SUSTAINED CONVECTIVE STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH WARM SST, LOW VWS, AND STRONG VENTILATION ALOFT.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS DAMREY WILL CONTINUE TO TRACK NORTH-NORTHWESTWARD UNDER THE STR. AFTER TAU 24, A MID-LATITUDE TROUGH TRANSITING FROM THE NORTHWEST WILL WEAKEN THE STR AND ALLOW THE SYSTEM TO TRACK MORE NORTHWARD THEN ACCELERATE NORTHEASTWARD AFTER TAU 36. THE FAVORABLE ENVIRONMENT WILL FUEL A MODEST INTENSIFICATION TO A PEAK OF 65KTS BY TAU 36 AS IT CRESTS THE STR AXIS. AFTERWARD, INCREASING VWS AND COOLING SST WILL BEGIN TO ERODE THE SYSTEM. CONCURRENTLY BY TAU 48, TS 08W WILL ENTER THE BAROCLINIC ZONE AND BEGIN EXTRA-TROPICAL TRANSITION AND, BY TAU 72, WILL TRANSFORM INTO A COLD-CORE LOW WITH EXPANDING GALE-FORCE WINDS.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH GRADUAL AND EVEN SPREAD TO 222NM BY TAU 72, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.

SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED // WTPN21 PHNC 252000 REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/242000Z AUG 23// AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PHNC 242000)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 160 NM EITHER SIDE OF A LINE FROM 11.9N 115.6W TO 15.6N 121.4W WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT IMAGERY AT 251800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 12.0N 116.0W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 10 KNOTS. 2. REMARKS: MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.