WDXS33 PGTW 090900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.1S 93.8E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 251 NM SOUTHWEST OF THE COCOS ISLANDS MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN ASYMMETRIC AND HIGHLY ELONGATED STRUCTURE WITH SMALL POCKETS OF CYCLING CONVECTION POSITIONED ROUGHLY IN THE CENTER OF THE NORTHWEST TO SOUTHEAST ORIENTED CIRRUS SHIELD. A 090732Z GMI 37GHZ MICROWAVE PASS REVEALS THAT THE LOWER-LEVEL STRUCTURE IS MORE SYMMETRICAL THAN WOULD BE EXPECTED BY LOOKING AT THE MSI. LOW-LEVEL BANDING FEATURES ARE WELL-DEFINED, WRAPPING INTO A DEFINED CENTER, WITH THE STRONGEST CONVECTIVE BANDS POSITIONED ACROSS THE NORTHERN PORTION OF THE CIRCULATION. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE DEFINED LLCC IN THE MICROWAVE IMAGE NOTED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES OUTLINED ABOVE. THE ENVIRONMENT IS MARGINALLY FAVORABLE IN THE AGGREGATE AND IMPROVING. SHEAR IS LOW TO MODERATE AND ON THE WAY DOWN, SSTS ARE WARM AND OUTFLOW IS STEADILY IMPROVING. ADDITIONALLY, THERE ARE SIGNS THAT THE UPPER-LEVEL FLOW IS SPLITTING UPSTREAM OF THE CORE, AND THE LOCALIZED SHEAR IS PROBABLY EVEN LESS THAN THE CURRENT CIMSS ESTIMATE, AND THE LATEST MICROWAVE IMAGERY SUPPORTS THE FACT THAT THE LOW-LEVEL STRUCTURE IS BETTER ORGANIZED THAN ANTICIPATED, WHICH COULD ALLOW FOR RAPID CONSOLIDATION AND DEVELOPMENT GOING FORWARD. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: THE SYSTEM IS GENERALLY IN A WEAK STEERING PATTERN; HOWEVER THE BULK OF THE STEERING INFLUENCE COMES FROM THE DEEP-LAYER SUBTROPICAL RIDGE SITUATED TO THE SOUTHWEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T3.0 - 45 KTS DEMS: T2.5 - 35 KTS APRF: T3.0 - 45 KTS CIMSS SATCON: 45 KTS AT 090330Z CIMSS ADT: 53 KTS AT 090530Z CIMSS AIDT: 42 KTS AT 090600Z CIMSS D-PRINT: 39 KTS AT 090600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 27-28 CELSIUS OUTFLOW: MODERATE RADIAL OTHER FACTORS: WEAK EQUATORWARD AND POLEWARD OUTFLOW. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 14S (TALIAH) IS CURRENTLY MOVING SLOWLY NORTHWESTWARD ALONG IN A WEAK STEERING PATTERN RIDGING TO THE SOUTHWEST, NORTHWEST AND SOUTHEAST AND A WEAKNESS OR TROF PASSING TO THE SOUTH. WHAT STEERING INFLUENCE THERE IS, COMES FROM THE NORTHEASTERN PERIPHERY OF THE STR CENTERED TO THE SOUTHWEST. THIS RIDGE IS FORECAST TO SHIFT NORTHWARD AND REORIENT TO A MORE NORTH-SOUTH AXIS OVER THE NEXT 24 TO 36 HOURS, WHILE THE RIDGE TO THE SOUTHEAST WILL STRENGTHEN AND DRIFT WESTWARD. TC 14S WILL IS EXPECTED TO CONTINUE TO DRIFT SLOWLY WEST-NORTHWESTWARD IN THIS WEAK PATTERN THROUGH TAU 36. AT THAT POINT, A WEAKNESS DEVELOPS IN THE RIDGE TO THE SOUTHWEST, WHILE THE RIDGE TO THE EAST CONTINUES TO BUILD AND MOVE CLOSER TO TC 14S, ENHANCING THE STEERING GRADIENT. TC 14S WILL TURN SHARPLY POLEWARD AFTER TAU 36 IN RESPONSE TO THESE CHANGES IN THE STEERING PATTERN AND ACCELERATE SOUTHWESTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN TERMS OF INTENSITY, THE STAGE IS BEING SET FOR THE SYSTEM INTENSIFY, POTENTIALLY RAPIDLY, OVER THE NEXT 24 TO 36 HOURS. SHEAR IS FORECAST TO EITHER STEADILY REDUCE OR REMAIN RELATIVELY CONSTANT, BUT THE SYSTEM IS ALREADY SEEN TO BE PUSHING BACK AGAINST THE SHEAR. THE MAIN FACTOR DRIVING THE INTENSIFICATION TREND WILL BE THE IMPROVEMENT IN UPPER-LEVEL OUTFLOW, PRIMARILY WESTWARD AND EQUATORWARD IN THE NEAR-TERM. A BRIEF LEVELING-OFF AROUND TAU 48 IS EXPECTED DUE TO A BRIEF UPTICK IN SHEAR. ANOTHER ROUND OF INTENSIFICATION WILL KICK OFF AFTER TAU 48, AS THE SYSTEM BEGINS TO TAP INTO A ROBUST POLEWARD OUTFLOW CHANNEL INTO THE BASE OF A SHARP 200MB TROF TO THE SOUTH, REACHING A PEAK OF AT LEAST 80 KNOTS AND POSSIBLY MUCH HIGHER. TC 14S WILL SUCCUMB TO RAPIDLY INCREASING SHEAR AND DRY AIR INTRUSION AFTER TAU 96, RAPIDLY WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN SURPRISINGLY GOOD AGREEMENT ACROSS THE FIRST 72 HOURS OF THE FORECAST. THE ONLY OUTLIERS ARE THE UKMET ENSEMBLE AND DETERMINISTIC TRACKERS WHICH CARRY THE SYSTEM TOO FAR NORTH AND ON TOO BROAD OF A TURN. THE REMAINDER OF THE CONSENSUS TRACKERS ARE CONFINED TO A MINISCULE CROSS-TRACK ENVELOPE CENTERED ON THE CONSENSUS MEAN. ALONG-TRACK SPREAD INCREASES SHARPLY AFTER THE SYSTEM MAKES THE TURN POLEWARD, UP TO 100NM BY TAU 72. BY TAU 120, CROSS-TRACK SPREAD INCREASES TO 250NM, BETWEEN THE UKMET ON THE WEST AND ECMWF AND GALWEM ON THE EAST, WHILE ALONG-TRACK UNCERTAINTY CONTINUES TO INCREASE TO 250NM AS WELL. THE JTWC FORECAST HEDGES TOWARDS THE ECMWF AFTER TAU 48, THOUGH RETAINS THE PACE OF THE CONSENSUS MEAN. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL TREND WITH A 30 KNOT SPREAD IN PEAK INTENSITY. ALL AVAILABLE GUIDANCE AGREES THAT THE SYSTEM WILL INTENSIFY QUICKLY FOR THE NEXT 24 HOURS, WITH A PEAK BETWEEN 55 AND 65 KNOTS, FOLLOWED BY A LEVELING-OFF FOR ABOUT 12 HOURS. THE GUIDANCE SPREADS OUT AFTER TAU 36, WITH COAMPS-TC KEEPING THE INTENSITY RELATIVELY FLAT THROUGH TAU 72, WHILE THE HAFS-A RAPIDLY INTENSIFIES THE SYSTEM TO A PEAK OF 85 KNOTS. THE JTWC FORECAST IS SITUATED NEAR THE CONSENSUS MEAN TO TAU 48, THEN GOES HIGHER THAN THE BULK OF THE GUIDANCE THROUGH THE PEAK AND REMAINS SLIGHTLY HIGHER THROUGH THE END OF THE FORECAST. RAPID INTENSIFICATION (RI) GUIDANCE INCLUDING DTOP AND FRIA CONTINUE TO TRIGGER WITH THIS FORECAST RUN AND THE FRIA AND RIPA PROBABILITIES CONTINUE TO SHOW A 25-30 PERCENT CHANCE OF RI IN THE NEAR-TERM AS WELL AS IN THE LONGER TERM THROUGH 72 HOURS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN