WTPN22 PGTW 120730 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)// REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/120521ZOCT2022// AMPN/REF A IS TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 180 NM EITHER SIDE OF A LINE FROM 14.8N 151.9E TO 19.7N 153.5E 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 18 TO 22 KNOTS. METSAT IMAGERY AT 120600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 15.8N 151.1E. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 02 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 16.0N 151.3E IS NOW LOCATED 15.8N 151.1E, APPROXIMATELY 325 NM EAST OF SAIPAN, NORTHERN MARIANA ISLANDS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICT A WELL HIDDEN LOW LEVEL CIRCULATION WITH BUILDING CONVECTION TO THE EAST. THIS LLC WAS REVEALED EARLIER IN A SCATTEROMETRY BULLSEYE THAT SHOWED ALONG THE NORTH, EAST, AND SOUTHERN QUADRANTS OF 99W, THERE LIES WINDS FIELDS OF 15-20 KNOTS WITH EMBEDDED 25 KNOT WINDS. A 120349Z AMSR 89 GHZ MICROWAVE PARTIAL PASS LENT A HAND WITH REVEALING THE LOWER LEVEL CONVECTIVE BANDS WRAPPING INTO THE WESTERN EDGE OF 99W. ENVIRONMENTAL ANALYSIS SHOWS 99W IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH THE SYSTEM BEING WITHIN A BUBBLE OF LOW VERTICAL WIND SHEAR (5-10 KTS) THAT IS SURROUND BY A BARRIER OF 40-50KTS OF SHEAR TO THE NORTH. OUTFLOW OF THE SYSTEM IS FAIR TOWARDS THE SOUTH AND EAST, ALONG THE SOUTHERN SIDE OF A SMALL TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL AND THE SSTS IN THE AREA WARM (29-30C) TO AID IN THE FUELING. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 99W WILL CONTINUE TO BE BLOCKED BY THE AREA OF HIGH PRESSURE TO THE NORTH OVER THE NEXT FEW HOURS, THUS CAUSING IT TO RETROGRADE TO THE SOUTHEAST, ALMOST COMPLETING A LOOP BY TAU 36, AND THEN HIGH TAIL IT TO THE NORTHEAST AS THAT BARRIER RIDGE SLIGHTLY WEAKENS. THE SYSTEM SHOULD INTENSIFY STEADILY OVER THE NEXT 24-36 HOURS AS IT MOVES INTO A MORE FAVORABLE OUTFLOW ENVIRONMENT AS THE TUTT CELL MOVES TO A POSITION TO THE NORTHWEST OF THE SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 17 TO 23 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. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 130730Z. 4. SEE REF A FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT LOCATED NEAR 15.8N 125.4E.// NNNN