Western Pacific: 18W(CONSON) gaining strength over South China Sea/Super Typhoon 19W(CHANTHU) back at CAT 5 over the Philippine Sea,EPacific & Atlantic updates,09/03utc

TS 18W(CONSON). WARNING 13 ISSUED AT 09/03UTC. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS CONSON WILL CONTINUE ON ITS CURRENT TRACK UP TO 36H; AFTERWARD, IT WILL TURN MORE WEST-NORTHWESTWARD AS THE SUBTROPICAL RIDGE IS WEAKENED BY A MID-LATITUDE TROUGH, PASS TO THE SOUTH OF HAINAN INTO THE GULF OF TONKIN, AND BY 120H, WILL MAKE LANDFALL OVER NORTHERN VIETNAM JUST SOUTH OF HANOI. THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A SLOW INTENSIFICATION TO A PEAK OF 70KNOTS/CAT 1 AT 48-72H. AFTERWARD, LAND INTERACTION WITH HAINAN AND LANDFALL OVER VIETNAM WILL RAPIDLY ERODE THE SYSTEM DOWN TO 35KNOTS.

TS 18W(CONSON).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A DISORGANIZED SYSTEM WITH FRAGMENTED FEEDER BANDS THAT IS STRUGGLING TO CONSOLIDATE AFTER IT CROSSED THE PHILIPPINE ARCHIPELAGO AND EXITED INTO THE SOUTH CHINA SEA. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE USING LOW CLOUD TRACING IN THE MSI LOOP AND LINED UP WITH A WEAK LOW LEVEL NOTCH FEATURE IN THE 082256Z AMSU-B MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSIGNED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED 6-HR CONVECTIVE SIGNATURE. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND WARM SSTS OFFSET BY WEAK UPPER LEVEL OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STR TO THE NORTHEAST.

TS 18W(CONSON).MODEL DISCUSSION: NUMERICAL MODELS ARE IN POOR AGREEMENT, SIGNIFICANTLY SPREADING TO 1500KM BY 120H WITH NAVGEM THE EXTREME OUTLIER ON THE RIGHT, DRASTICALLY DEFLECTING THE VORTEX NORTHWARD AFTER 36H, A POSSIBLE EXCESSIVE BINARY INTERACTION WITH A SECONDARY CYCLONE (STY 19W IN THE PHILIPPINE SEA). IN VIEW OF THESE, THERE IS LOW CONFIDENCE IN THE FULL EXTENT OF THE JTWC TRACK FORECAST. THERE IS MEDIUM CONFIDENCE IN THE INTENSITY FORECAST UP TO 72H AND LOW CONFIDENCE AFTERWARD.

STY 19W(CHANTHU). WARNING 12 ISSUED AT 09/03UTC.SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: STY CHANTU WILL COMMENCE ON A RECURVATURE TRACK PATTERN AS IT TURNS MORE WEST-NORTHWESTWARD THEN NORTHWESTWARD AFTER 24H AS IT ROUNDS THE WESTERN EDGE OF THE SUBTROPICAL RIDGE(STR). AFTER 48H, IT WILL CROSS TAIWAN AS IT TRACKS NORTHWARD AND CRESTS THE STR AXIS BY 72h. AFTERWARD, THE SYSTEM WILL TURN MORE NORTH- NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR, BRUSH THE CHINESE COAST AND BY 120H WILL BE JUST SOUTH OF SHANGHAI. THE FAVORABLE ENVIRONMENT WILL SUSTAIN THE CURRENT INTENSITY UP TO 12H; AFTERWARD, SLOWLY INCREASING VERTICAL WIND SHEAR(VWS) ASSOCIATED UPPER LEVEL CROSS WINDS AND SOME LAND INTERACTION AS IT CLIPS THE NORTHEASTERN TIP OF LUZON, WILL SLOWLY WEAKEN THE SYSTEM TO 125KNOTS/CAT 4 BY 48H AS IT CROSSES THE LUZON STRAIT. AFTER 48H, A MORE DRASTIC EROSION WILL OCCUR AS THE CYCLONE DRAGS ACROSS TAIWAN AND INTO HIGHER VWS, DOWN TO 100KNOTS/CAT 3 AS IT EXITS INTO THE TAIWAN STRAIT AROUND 72H. FURTHER LAND INTERACTION, THIS TIME WITH THE CHINESE COAST, WILL FURTHER WEAKEN THE SYSTEM MORE RAPIDLY DOWN TO 60KNOTS BY 120H AS IT APPROACHES SHANGHAI.

STY 19W(CHANTHU). SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A COMPACT, INTENSE, AND HIGHLY-SYMMETRICAL SYSTEM WITH A SHARPLY OUTLINED 9-KM PINHOLE EYE, WHERE THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE. CONVECTIVE TOPS AROUND THE EYEWALL HAVE SLIGHTLY DEEPENED AS EVIDENCED BY COOLER TEMPERATURES FROM 6HRS PRIOR. THE INITIAL INTENSITY IS ALSO ASSIGNED WITH HIGH CONFIDENCE BASED ON CONGRUENT AND CONCENTRIC AGENCY DVORAK FIXES AND REFLECTS THE SLIGHT 6-HR INTENSIFICATION. ANALYSIS INDICATES CONTINUED FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND STRONG RADIAL OUTFLOW ALOFT, AND VERY WARM ALONG-TRACK SSTS OVER THE PHILIPPINE SEA. STY 19W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED STR TO THE NORTH.

STY 19W(CHANTHU). MODEL DISCUSSION: NUMERICAL MODELS ARE NOW UNIFIED WITH A RECURVATURE TRACK FORECAST SOLUTION WITH A GRADUAL AND EVEN SPREADING TO 490KM BY 120H WITH NVGM THE NOTABLE RIGHT-OF-TRACK OUTLIER ON THE RIGHT MARGIN OF THE ENVELOPE AND 195KM AWAY FROM THE MAIN CLUSTER AT 120H. IN VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO 72H, AND MEDIUM CONFIDENCE AFTERWARD WHERE IT IS LAID JUST TO THE LEFT OF MODEL CONSENSUS TO OFFSET NVGM. THERE IS ALSO HIGH CONFIDENCE IN THE INTENSITY FORECAST UP TO 72H, WHERE IT IS HELD SLIGHTLY HIGHER THAN MODEL CONSENSUS TO BETTER REFLECT THE FAVORABLE ENVIRONMENT, AND MEDIUM CONFIDENCE AFTERWARD, IN VIEW OF THE UNCERTAIN IMPACTS THAT VERTICAL WIND SHEAR AND LAND INTERACTIONS WILL BRING.

STY 19W(CHANTHU). HWRF AT 08/18UTC. INTENSITY GUIDANCE: 138KNOTS AT +0H.

09/00UTC.

EASTERN PACIFIC. TS 15E(OLAF). WARNING 6 ISSUED AT 09/04UTC.

TS 15E(OLAF). GUIDANCE.

09/00UTC.

ATLANTIC. HU 12L(LARRY). WARNING 34 ISSUED AT 09/03UTC.

HU 12L(LARRY). GUIDANCE.

TS 13E(MINDY). WARNING 2 ISSUED AT 09/03UTC.

TS 13L(OLAF). GUIDANCE.