Extremely busy Southern Hemisphere// 19P(RAE) and 20S(BIANCA) CAT 2 US//2421utc

JTWC IS ISSUING 12 HOURLY WARNINGS ON 18P, 19P, 20S AND 21P. 3 HOURLY SATELLITE BULLETINS ARE ISSUED ON 97S AND 95S.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE 20S (BIANCA) WITH A 24 NM SLIGHTLY RAGGED EYE AND A MUCH MORE SYMMETRIC CENTRAL DENSE OVERCAST SURROUNDING THE EYEWALL. ENVIRONMENTAL ANALYSIS INDICATES THAT 20S IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (26-27 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN ANIMATED EIR SATELLITE IMAGERY. THE INITIAL INTENSITY OF 95 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE EXCEPTION OF NAVGEM, WHICH TAKES THE SYSTEM FURTHER WESTWARD THAN THE REMAINDER OF GUIDANCE. THE JTWC TRACK FORECAST IS PLACED SLIGHTLY TO THE EAST OF CONSENSUS THROUGH THE ENTIRE FORECAST PERIOD TO OFFSET NAVGEM. INTENSITY GUIDANCE IS IN MODERATE AGREEMENT. GFS DEPICTS A MUCH WEAKER VORTEX THAN THE MESOSCALE MODELS THROUGH TAU 36. HAFS-A ALSO SUGGESTS FURTHER INTENSIFICATION OVER THE NEXT 12 HOURS, DIFFERING FROM THE REMAINDER OF GUIDANCE. THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY BELOW HAFS-A THROUGHOUT THE FORECAST PERIOD WITH MEDIUM CONFIDENCE.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION WRAPPING AROUND THE LOW-LEVEL CIRCULATION CENTER (LLCC), CLEARLY ATTEMPTING TO DEVELOP AN EYE BUT NOT QUITE THERE. THE CENTER IS CLEARING SLIGHTLY, PARTIALLY REVEALING THE LLCC. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 24-615Z F-17 SSMIS COLOR-ENHANCED 37GHZ IMAGE HIGHLIGHTING A MICROWAVE EYE FEATURE WITH A DRY SLOT TO THE SOUTHWEST. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH HIGH CONFIDENCE MEDIUM CONFIDENCE BASED ON THE OBJECTIVE CIMSS INTENSITY DATA LISTED BELOW, LENDING HIGHER INTENSITY VALUES THAN THE AGENCY FIXES.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG AGREEMENT THAT THE SYSTEM WILL CURVE SOUTHEASTWARD THROUGHOUT THE FORECAST PERIOD. THE CROSS-TRACK SPREAD OF THE JTWC MULTI-MODEL CONSENSUS IS 65NM BY TAU 48. THE INTENSITY GUIDANCE DROPPED SIGNIFICANTLY SINCE THE LAST INITIALIZATION, BUT REMAINS IN GOOD AGREEMENT THAT A PEAK INTENSITY WILL OCCUR WITHIN THE NEXT 12-24 HOURS.

WTXS21 PGTW 242200 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 97S)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 080 NM EITHER SIDE OF A LINE FROM 18.2S 51.3E TO 17.4S 55.8E 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 28 TO 33 KNOTS. METSAT IMAGERY AT 242200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 18.2S 51.6E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 03 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 97S) PREVIOUSLY LOCATED NEAR 18.0S 51.5E IS NOW LOCATED NEAR 18.2S 51.6E, APPROXIMATELY 282 NM NORTHWEST OF LA REUNION. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A RAPIDLY CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC), WITH FLARING CONVECTION OVER THE CENTER. A 241725Z ASCAT METOP-B IMAGE REVEALS 35 KNOT WINDS WITHIN THE NORTHEASTERN QUADRANT. HOWEVER, THE 35 KNOT WIND BARS ARE FLAGGED IN THE QC VERSION OF THE IMAGE. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (VWS) OF 10-15 KNOTS, GOOD EQUATORWARD UPPER-LEVEL OUTFLOW AND WARM SEA SURFACE TEMPERATURES (SST) OF 29-30 C. BOTH DETERMINISTIC AND ENSEMBLE MODELS CONTINUE TO AGREE, FORECASTING GRADUAL DEVELOPMENT OF INVEST 97S OVER THE NEXT 24 HOURS WITH A GENERALLY EASTWARD TRACK. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 252200Z.// NNNN