Western Pacific: 18W(CONSON) set to intensify once over the South China Sea, 19W(CHANTHU) forecast to reach CAT 4 by 48h//Eastern Pacific & Atlantic updates,07/09utc

JTWC ARE ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 18W AND 19W.

TS 18W(CONSON). WARNING 6 ISSUED AT 07/09UTC.SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 18W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD, GENERALLY TOWARDS THE MANILA METRO AREA, OVER THE NEXT 24 HOURS AND EMERGE INTO THE SOUTH CHINA SEA ONCE MORE NEAR 36H, MOVING ALONG THE WESTERN PERIPHERY OF THE NEAR EQUATORIAL RIDGE(NER) CENTERED TO THE EAST AND THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE(STR)TO THE NORTH. AFTER EMERGING INTO THE SOUTH CHINA SEA, THE TRACK OF 18W IS FORECAST TO FLATTEN OUT, BECOMING MORE WEST-NORTHWESTWARD AS THE STR TO THE NORTH BECOMES THE DOMINATE STEERING MECHANISM. AS THE SYSTEM TRACKS OVER THE SIBUYAN SEA IT IS LIKELY TO MAINTAIN ITS CURRENT INTENSITY, AND COULD POTENTIALLY SEE SHORT-TERM INTENSIFICATION WHILE OVER THE WARM WATERS, BEFORE MAKING ANOTHER LANDFALL ON THE SOUTHERN COAST OF LUZON SOUTHEAST OF MANILA. THE RUGGED TERRAIN WILL SERVE TO WEAKEN TS 18W TO 40 KNOTS BEFORE REEMERGING OVER OPEN WATERS NEAR 36H. ENVIRONMENTAL CONDITIONS OF LOW (10-15 KTS) VERTICAL WIND SHEAR, MODERATE WESTWARD OUTFLOW AND WARM (29C) SSTS, ARE EXPECTED TO REMAIN FAVORABLE AND SUPPORT SLOW BUT STEADY INTENSIFICATION AFTER 48H, REACHING A PEAK OF 75 KNOTS/CAT 1 BY 120H.

TS 18W(CONSON). SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM 18W CONTINUES TO WEAKEN AS IT HAS TRACKED ACROSS MASBATE ISLAND OVER THE PREVIOUS SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) STILL INDICATES THAT THE OVERALL ROTATION ASSOCIATED WITH TS CONSON REMAINS INTACT, BUT STRUCTURALLY IT HAS BECOME SOMEWHAT RAGGED. A 070527Z AMSR2 89GHZ MICROWAVE IMAGE REVEALS WEAK SPIRAL BANDS WRAPPING INTO A RAGGED AND BROAD LOW EMISSIVITY REGION. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AMSR2 IMAGE AND SUPPORTED BY ANIMATED RADAR DATA FROM THE PHILIPPINES RADAR NETWORK. SURFACE OBSERVATIONS FROM MASBATE CITY INDICATE SOUTHEASTERLY WINDS WITH GUSTS UP TO NEAR 40 KNOTS AND SEA LEVEL PRESSURES NEAR 997MB. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON A PGTW DATA-T OF T3.0 (45 KTS) AND AN RJTD CI OF T3.0, WITH SUPPORT FROM THE SURFACE OBSERVATION FROM MASBATE CITY. ANIMATED WATER VAPOR IMAGERY SHOWS THE SYSTEM HAS GOOD RADIAL OUTFLOW WITH WEAK POLEWARD FLOW INTO A TUTT CELL POSITIONED TO THE NORTHEAST.

TS 18W(CONSON). MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH 48H, WITH A SPREAD IN THE GUIDANCE ENVELOPE OF ONLY 140KM AT 48H. HOWEVER, THE GUIDANCE IS SHOWING INCREASING UNCERTAINTY FROM 72H ONWARDS, WITH MULTIPLE MODELS (GFS, GFS ENSEMBLE, HWRF) NOW SHOWING A SIGNIFICANT SLOWDOWN IN THE MID-SOUTH CHINA SEA AROUND 72H. GLOBAL MODEL FIELDS FOR THE GFS SHOW THE STR TO THE NORTH WEAKENING AND MOVING INTO A POSITION DUE NORTH OF TS 18W, SLACKENING THE STEERING FLOW AND RESULTING IN A VERY SLOW OR EVEN QUASI-STATIONARY MOVEMENT AFTER 96H. THE NAVGEM MODEL MEANWHILE SHOWS THE SYSTEM SIGNIFICANTLY WEAKER, AND BEING ABSORBED INTO THE OVERALL FLOW ASSOCIATED WITH TY 19W TO THE NORTH. HOWEVER, THIS SCEANRIO IS CONSIDERED HIGHLY UNLIKELY AND IS DISCOUNTED. THE REMAINDER OF THE GUIDANCE REMAINS CONSISTENT WITH PREVIOUS RUNS AND SUPPORTS THE JTWC FORECAST TRACK WHICH LIES ON THE SOUTHERN SIDE OF THE CONSENSUS ENVELOPE WITH MEDIUM CONFIDENCE. THERE IS MEDIUM CONFIDENCE IN THE INTENSITY FORECAST THROUGH 72H DUE TO THE NEAR-TERM UNCERTAINTIES SURROUNDING THE EFFECTS OF LAND INTERACTION. IN THE LONG-TERM, THERE IS LOW CONFIDENCE, AS THE ULTIMATE PEAK INTENSITY OF TS 18W IS HIGHLY DEPENDENT ON HOW MUCH OF THE SYSTEM REMAINS AFTER TRANSITING ACROSS LUZON. GUIDANCE IS IN FAIRLY GOOD AGREEMENT, THOUGH THE HWRF CONTINUES TO SHOW UNREALISTIC RAPID INTENSIFICATION IN THE FIRST 12 HOURS WHILE THE SYSTEM IS OVER THE SIBUYAN SEA. THE JTWC FORECAST LIES CLOSE TO THE INTENSITY CONSENSUS THROUGH THE DURATION OF THE FORECAST PERIOD.

TS 18W(CONSON). HWRF AT 07/00UTC. INTENSITY GUIDANCE: 91KNOTS AT +120H.

TY 19W(CHANTHU). WARNING 6 ISSUED AT 07/09UTC.SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 19W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD THROUGH T48H ALONG THE SOUTHERN PERIPHERY OF THE DEEP SUBTROPICAL RIDGE(STR) CENTERED TO THE NORTH. GLOBAL MODEL FIELDS INDICATE THAT BY AROUND 48H THE RIDGE TO THE NORTH WILL BEGIN TO WEAKEN SLIGHTLY, ERODED BY THE TRANSIT OF A MINOR SHORTWAVE TROUGH, WHILE THE STR CENTER WILL MOVE EAST AND THE WESTERN PERIPHERY OF THIS RIDGE WILL REORIENT TO A NORTH-SOUTH AXIS. THE NET RESULT FOR TY 19W WILL BE A GRADUAL TURN POLEWARD TOWARDS THE COAST OF SOUTHERN TAIWAN. THE SYSTEM IS EXPECTED TO MAKE LANDFALL ALONG THE SOUTHERN TIP OF TAIWAN NEAR 96H THEN MOVE INTO THE SOUTHERN TAIWAN STRAIT. TY 19W HAS EXHIBITED DRAMATIC IMPROVEMENTS IN ITS CONVECTIVE STRUCTURE AND IS BEGINNING TO RAPIDLY INTENSIFY. THE RAPID INTENSIFICATION PREDICTION AID (RIPA) HAS CONTINUED TO BE TRIGGERED, PROVIDING INCREASING CONFIDENCE IN THE FORECAST INTENSITIES THROUGH 48H. THE SYSTEM IS NOW FORECAST TO INTENSIFY TO 95 KNOTS/CAT 2 BY 24H AND 115 KNOTS/CAT 4 BY 48H UNDER VERY FAVORABLE ENVIRONMENTAL CONDITIONS OF WARM (30C) SSTS, LOW (5-10 KTS) VERTICAL WIND SHEAR(VWS) AND RADIAL OUTFLOW. AS THE SYSTEM APPROACHES TAIWAN, IT IS EXPECTED TO TAP INTO SOME POLEWARD OUTFLOW, BUT AT THE SAME TIME SSTS ARE FORECAST TO COOL SLIGHTLY WHILE VWS IS FORECAST TO INCREASE. THESE PARAMETERS SHOULD OFFSET ONE ANOTHER, RESULTING IN THE SYSTEM MAINTAINING INTENSITY THROUGH LANDFALL, WITH SIGNIFICANT WEAKENING THEREAFTER AS THE SYSTEM INTERACTS WITH THE RUGGED TERRAIN OF TAIWAN. TROPICAL STORM CONSON (18W) IS LOCATED APPROXIMATELY 1325KM TO THE SOUTHWEST. THE TWO SYSTEMS ARE EXPECTED TO CLOSE TO WITHIN 1050-1090KM AROUND 72H BUT THE PROBABILITY OF BINARY INTERACTION REMAINS LOW DUE TO THE COMPACT NATURE OF BOTH SYSTEMS.

TY 19W(CHANTHU). SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES THAT TY 19W HAS CONTINUED TO QUICKLY CONSOLIDATE AND HAS STARTED TO RAPIDLY INTENSIFY. ANIMATED VISIBLE IMAGERY SHOWS VORTICAL HOT TOWERS (VHT) DEVELOPING AROUND THE CENTER OF THE SYSTEM AND ROTATING UPSHEAR, INDICATIVE OF THE ONSET OF RAPID INTENSIFICATION (RI). ADDITIONALLY, A 070350Z AMSR2 COLORIZED 37GHZ MICROWAVE IMAGE SHOWED A VERY SMALL MICROWAVE EYE FEATURE SURROUNDED BY A CYAN RING, PROVIDING ANOTHER INDICATOR OF NEAR-TERM RI. THE AMSR2 IMAGERY PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS SET AT 65 KNOTS, IS WELL ABOVE THE MAJORITY OF THE MULTI-AGENCY AND OBJECTIVE CURRENT INTENSITY ESTIMATES. HOWEVER, GIVEN THE MULTIPLE INDICATORS OF THE ONSET OF RI, THE ANTICIPATED NEAR-TERM DEVELOPMENT OF AN EYE, AND THE COMPACT NATURE OF THE SYSTEM (LEADING TO POTENTIALLY LOW DVORAK ESTIMATES) PROVIDE HIGH CONFIDENCE TO THE INITIAL INTENSITY. WHILE SMALL IN NATURE, THE SYSTEM CONTINUES TO EXHIBIT RADIAL OUTFLOW, AND VERY LOW WIND SHEAR VALUES. THE SYSTEM LIES OVER VERY WARM (30C) AND HIGH OHC WATERS, PROVIDING AMPLE ENERGY TO SUPPORT THE RI.

TY 19W(CHANTHU). MODEL DISCUSSION: CONFIDENCE IN THE SHORT-TERM FORECAST THROUGH 48H IS HIGH, WITH A 185KM SPREAD OF CONSENSUS MEMBERS AT 48H. GFS AND ITS ENSEMBLE ARE SHOWING A BIT MORE EQUATORWARD TRACK, BUT OVERALL ALL MEMBERS ARE IN AGREEMENT ON THE TRACK THROUGH 48H. THEREAFTER THINGS BEGIN TO DIVERGE SIGNIFICANTLY. AT 96H, THE GFS, GFS ENSEMBLE, NAVGEM AND HWRF TURN SHARPLY POLEWARD ALONG THE EAST COAST OF TAIWAN, WHILE THE UKMET, UKMET ENSEMBLE, ECMWF AND ECMWF ENSEMBLE CONTINUE THEIR CONSISTENT TRACK TO THE SOUTH OF TAIWAN, LEADING TO A 795KM SPREAD AT 48H. THE NAVGEM AND GFS MODELS HAVE BEEN HIGHLY INCONSISTENT RUN TO RUN, THOUGH THE CURRENT AND MOST RECENT RUNS HAVE BEEN CONSISTENT OVERALL ON THE SHARP TURN POLEWARD EAST OF TAIWAN. THUS THERE IS LESS PRESSURE TO DISCOUNT THEM ALTOGETHER, BUT NOT YET ENOUGH CONFIDENCE TO FULLY SHIFT THE TRACK. HENCE THE JTWC FORECAST TRACK REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND REMAINS SOUTH OF THE CONSENSUS MEAN WITH MEDIUM CONFIDENCE.

TY 19W(CHANTHU). HWRF AT 07/00UTC. INTENSITY GUIDANCE: 128KNOTS AT +90H.

TY 19W(CHANTHU). THE FORECAST TRACK KEEPS THE CYCLONE OVER WARM SEAS WITH HIGH OCEAN HEAT CONTENT WHILE CONDITIONS ARE FAVOURABLE ALOFT TOO. JTWC IS CALLING FOR RAPID INTENSIFICATION NEXT 48H.

07/00UTC.

EASTERN PACIFIC. INVEST 96E. TROPICAL CYCLONE FORMATION ALERT ISSUED AT 07/06UTC. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 220 KM EITHER SIDE OF A LINE FROM 17.4N 106.6W TO 19.7N 108.7W 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 070000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 17.4N 106.7W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 13 KM/H. 2. REMARKS:REMARKS: THE AREA OF CONVECTION (INVEST 96E) PREVIOUSLY LOCATED NEAR 16.2N 104.4W IS NOW LOCATED NEAR 17.4N 106.7W, APPROXIMATELY 295 KM SOUTHWEST OF MANZANILLO, MEXICO. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND A 0111Z SSMIS 91GHZ IMAGE DEPICT A SMALL POCKET OF CONVECTION TO THE EAST OF A BROAD LOW LEVEL CIRCULATION (LLC). INVEST 96E IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT CHARACTERIZED BY STRONG OUTFLOW ALOFT, LOW VERTICAL WIND SHEAR (VWS), AND WARM (28-29C) SEA SURFACE TEMPERATURES (SST).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 REMAINS HIGH.

INVEST 96E. GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT INVEST 96E WILL CONSOLIDATE AND STRENGTHEN AS IT PROPAGATES NORTH- NORTHWESTWARD DURING THE NEXT 24-36 HOURS.

07/00UTC.

ATLANTIC. HU 12L(LARRY). WARNING 27 ISSUED AT 07/09UTC. CURRENT INTENSITY IS 105KNOTS/CAT 3 AND IS FORECAST TO DECREASE TO 95KNOTS/CAT 2 BY 48H AND THEN TO FALL DOWN TO 75KNOTS/CAT 1 BY 11/06UTC.

HU 12L(LARRY). GUIDANCE.

07/09UTC. CIRA.