TD 02W forecast to reach Typhoon intensity by 72h// TC 23P(FILI): subtropical transition by 36h// Invests 94W & 96W, 07/09utc

JTWC IS ISSUING 6HOURLY WARNINGS ON TD 02W AND TC 23P(FILI). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON BOTH SYSTEMS.

07/0930UTC.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOWLY-CONSOLIDATING, SYMMETRIC LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FORMATIVE CONVECTIVE BANDING OVER THE NORTHERN AND WESTERN SEMICIRCLES. A 070559Z GMI 89GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS IMPROVED ORGANIZATION WITH SHALLOW BANDING WRAPPING INTO A RAGGED LLCC AND FRAGMENTED DEEP CONVECTIVE BANDING PRIMARILY OVER THE NORTHERN SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI AND GMI IMAGE. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH MODERATE WESTWARD OUTFLOW AND LOW VERTICAL WIND SHEAR (VWS) AS WELL AS WARM SST VALUES AND HIGH OCEAN HEAT CONTENT. INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE AND IS HEDGED ABOVE THE DVORAK ESTIMATES BASED ON THE CIMSS ADT ESTIMATE AND IMPROVED CONVECTIVE STRUCTURE. THE 070000Z SOUNDINGS FROM BOTH CHUUK AND GUAM INTERNATIONAL AIRPORT INDICATE DEEP EASTERLY FLOW REFLECTING THE STRONG EAST-WEST ORIENTED SUBTROPICAL RIDGE POSITIONED TO THE NORTH.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE JTWC FORECAST TRACK HAS SHIFTED SIGNIFICANTLY WEST OF THE PREVIOUS FORECAST, ESPECIALLY IN THE EXTENDED FORECAST PERIOD. FORECAST DISCUSSION: TD 02W IS FORECAST TO TRACK WEST-NORTHWESTWARD THEN NORTHWESTWARD ALONG THE SOUTHERN AND SOUTHWESTERN PERIPHERIES OF THE SUBTROPICAL RIDGE (STR) THROUGH THE FORECAST PERIOD. AS MENTIONED PREVIOUSLY, THE LOW- TO MID-LEVEL STR IS CURRENTLY STRONG AND IS ORIENTED EAST-WEST SUPPORTING THE WEST-NORTHWESTWARD TRACK IN THE EARLY PART OF THE FORECAST. TD 02W WILL INTENSIFY SLOWLY THROUGH 36H AS IT CONSOLIDATES UNDER GENERALLY FAVORABLE CONDITIONS BUT IS FORECAST TO INTENSIFY AT A STEEPER RATE AFTER 36H AS POLEWARD OUTFLOW IMPROVES. THE PEAK INTENSITY OF 90 KNOTS/CAT 2 US IS EXPECTED NEAR 120H.

070559Z GMI 89GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS IMPROVED ORGANIZATION WITH SHALLOW BANDING WRAPPING INTO A RAGGED LLCC AND FRAGMENTED DEEP CONVECTIVE BANDING PRIMARILY OVER THE NORTHERN SEMICIRCLE.

MODEL DISCUSSION: WITH THE EXCEPTION OF GFS, THE BULK OF NUMERICAL MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK AND SHIFT WEST FROM THE PREVIOUS JTWC TRACK FORECAST. THE 070000Z ECMWF ENSEMBLE STRIKE PROBABILITY PRODUCT INDICATES A NARROW CONE OF 60-70 PERCENT STRIKE PROBABILITY WEST OF 140E THROUGH 96H, WHICH SUPPORTS THE JTWC FORECAST TRACK. THE COAMPS-TC ENSEMBLE AND UK MET ENSEMBLE (MOGREPS) ALSO SHOW A SIMILAR GROUPING OF SOLUTIONS WEST OF 140E. GLOBAL MODELS INDICATE A BROAD MIDLATITUDE RIDGE PERSISTING SOUTH OF JAPAN, WHICH WILL STRENGTHEN THE EXISTING STR. ADDITIONALLY, THERE ARE NO DYNAMIC SHORTWAVE TROUGHS SUFFICIENT TO WEAKEN THE STR THROUGH THE FIRST THREE DAYS; IN FACT, THERE IS ONLY ONE SIGNICANT SHORTWAVE TROUGH PASSING WELL TO THE NORTH OVER JAPAN WITHIN THE NEXT 24 HOURS. GFS IS THE SOLE OUTLIER AND IS ON THE EASTERN EDGE OF THE AIDS ENVELOPE. GFS APPEARS TO BE STRUGGLING WITH THE FORMATION OF THIS SYSTEM IN THE EARLY TAUS AND SHOWS A NORTHWARD TURN INTO THE EAST-WEST ORIENTED STR FROM 24H TO 48H. AFTER 48H, GFS ALSO RAPIDLY DEVELOPS ANOTHER SYSTEM EAST OF THE PHILIPPINES (ABOUT 1700 KM WEST), WHICH INTERACTS WITH AND SLINGS 02W DIRECTLY INTO AND THROUGH THE STR WITH NO EVIDENCE OF ANY DYNAMIC SHORTWAVE TROUGHS THAT COULD POSSIBLY WEAKEN THE STR. ADDITIONALLY, THE NORTHWARD TRACK IS LESS PROLONGED IN THE 070000Z RUN VERSUS THE 061800Z RUN AND THE TRACKER SHIFTED FURTHER WEST AWAY FROM GUAM. BOTTOMLINE: THERE ARE CONCERNING ISSUES WITH GFS WITHIN THE SYNOPTIC STEERING ENVIRONMENT THAT ARE ODD AND UNLIKELY, THEREFORE, THE JTWC FORECAST TRACK IS SHIFTED CLOSER TO THE JTWC MULTI-MODEL CONSENSUS WITH THE BULK OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION WITH DEEP CONVECTION SHEARED TO THE EAST DUE TO HIGH SOUTHWESTERLY VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI. ALTHOUGH THE LLC IS EXPOSED, A 070537Z SSMIS 37GHZ MICROWAVE IMAGE REVEALS A WELL-ORGANIZED LLC WITH CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 3.0-3.5, WHICH IS INLINE WITH THE 070313Z SATCON ESTIMATE. UPPER-LEVEL ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH HIGH VWS AND MODERATE EASTWARD OUTFLOW.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 23P IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) AND IS INTERACTING WITH THE SUBTROPICAL WESTERLIES RESULTING IN LIMITED OUTFLOW AND HIGH VWS, WHICH WILL SERVE TO GRADUALLY WEAKEN THE SYSTEM AS IT TRACKS SOUTHEASTWARD TO EAST-SOUTHEASTWARD OVER THE NEXT 36 HOURS. THE SYSTEM IS EXPECTED TO TRANSITION TO A SUBTROPICAL CYCLONE BY 36H UNDER STRENGTHENING WESTERLIES AND INCREASING (40 KNOTS) VWS WITH SIGNIFICANT DRY AIR ENTRAINMENT AND UPPER-LEVEL CONVERGENT FLOW. THE SYSTEM SHOULD MAINTAIN GALE-FORCE WINDS OVER THE SOUTHERN SEMICIRCLE. AFTER 36H, THE SYSTEM WILL LIKELY SLOW AND BECOME QUASI-STATIONARY AS A STRONG HIGH BUILDS TO THE SOUTH.

MICROWAVE IMAGE REVEALS A WELL-ORGANIZED LLC WITH CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER.

MODEL DISCUSSION: THROUGH 36H, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH 24H WITH INCREASING UNCERTAINTY AFTER 24H DUE TO THE ERRATIC, QUASI-STATIONARY MOTION ANTICIPATED AS THE STRONG HIGH BUILDS IN. OVERALL CONFIDENCE IN THE JTWC FORECAST TRACK IS MEDIUM. INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH THE BULK OF THE GUIDANCE MAINTAINING A 30-45 KNOT SYSTEM. DECAY SHIPS GUIDANCE AND COAMPS-TC (NAVGEM VERSION) ARE DISSIPATING THE SYSTEM AFTER 36H. OVERALL CONFIDENCE IN THE JTWC INTENSITY FORECAST IS MEDIUM.