TC 21S(OLGA) peaked as a powerful CAT 4 US// ECMWF 10 Day Storm Tracks// 0803utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 21S(OLGA)

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS TC 21S CONTINUED TO SIGNIFICANTLY DEGRADE AS EVIDENCED BY EXCESSIVE POLEWARD ELONGATION, WARMING CLOUD TOPS, AND CONVECTIVE FRAGMENTATION MOSTLY DUE TO HIGH (30+ KNOTS) WESTERLY VWS. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A SMALL CLUSTER OF WARM PIXELS IN THE 072350Z EIR IMAGE, ADJUSTED FOR TILT, AND LINED UP WITH A SEMI-EXPOSED MICROWAVE LLC FEATURE IN THE 072150Z SSMIS 91GHZ IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE RAPID WEAKENING TREND. ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH THE STRONG POLEWARD OUTFLOW AND WARM SST OFFSET BY STRONG VWS AND DRY AIR INTRUSION AT THE LOWER LEVELS WRAPPING IN FROM THE SOUTHWEST PERIPHERIES.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC OLGA WILL CONTINUE SOUTHWESTWARD ALONG THE NORTHWEST EDGE OF THE SOUTHWEST EXTENSION OF THE STEERING STR. THE HIGHLY UNFAVORABLE ENVIRONMENT WILL ONLY GET WORSE WITH INCREASING VWS AND COOL DRY AIR INTRUSION. THESE WILL ENHANCE RAPID EROSION LEADING TO DISSIPATION BY TAU 96, POSSIBLY SOONER.

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION MODELS ARE IN OVERALL GOOD AGREEMENT WITH AN EVEN BUT INCREASINGLY WIDENING SPREAD TO 355NM BY TAU 96, LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST.