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JTWC/16W/#07/08-08 12Z Prognostic Reasoning
WDPN32 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 20.8N 144.2E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 428 NM NORTH OF ANDERSEN AFB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 15 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 16W APPEARS TO BE UNDERGOING ANOTHER ATTEMPT AT
VORTEX CONSOLIDATION AND ALIGNMENT, VERY SIMILAR TO THE ATTEMPT
MADE 24 HOURS AGO. TIME WILL TELL IF THIS TIME IT WILL ACTUALLY
SUCCEED. OVER THE PAST SIX HOURS OR SO, ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY SHOWED DEEP CONVECTION FORMING IN THE
SOUTHEASTERN QUADRANT AND THEN WRAPPING UPSHEAR WHERE IT EVENTUALLY
ENVELOPED THE LOW LEVEL CIRCULATION CENTER (LLCC). SUBSEQUENT
IMAGERY SHOWS POWERFUL BURSTS OF DEEP CONVECTIVE ACTIVITY, WITH
OVERSHOOTING TOP TEMPERATURES EXCEEDING -85C AND IMPRESSIVE AMOUNTS
OF LIGHTNING ACTIVITY, CONTINUING TO FLARE UP IN THE VICINITY OF
THE ASSESSED LLCC. A 081037Z ASCAT-B PASS REVEALED THE LLCC TUCKED
UP UNDER THE NORTHERN EDGE OF THE CONVECTIVE MASS IN THE EIR AND
PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION. A 080832Z RCM-3
SAR PASS SHOWED A COMPACT WIND FIELD, WITH THE HIGHEST WINDS
LOCATED ALONG THE EASTERN FLANK OF THE CIRCULATION, THOUGH THERE
APPEARS TO BE SOME ICE CONTAMINATION IN THE SAR IMAGERY AND THUS
THE WINDSPEED MEASUREMENTS ARE TOO HIGH. BUT BETWEEN THE TWO
WINDSPEED MEASUREMENTS, AND THE T3.0 DVORAK CURRENT INTENSITY
ESTIMATES FROM MULTIPLE AGENCIES, THERE IS AMPLE SUPPORT FOR A HIGH
CONFIDENCE INITIAL INTENSITY ESTIMATE. ENVIRONMENTAL CONDITIONS
REMAIN FAVORABLE, WITH LOW NORTHEASTERLY DEEP-LAYER SHEAR, WARM
SSTS AND GOOD EQUATORWARD OUTFLOW. CIRA DERIVED MOTION VECTOR (DMV)
WINDS INDICATE INCREASING WESTWARD OUTFLOW AND SPLIT FLOW UPSTREAM
(NORTHEAST) OF THE LLCC.
INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA.
CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T2.5 - 35 KTS
RCTP: T3.0 - 45 KTS
KNES: T3.0 - 45 KTS
CIMSS ADT: 43 KTS AT 081130Z
CIMSS AIDT: 40 KTS AT 081130Z
CIMSS D-PRINT: 37 KTS AT 081130Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
OTHER FACTORS: SMALL REGION OF DRY MID-LEVEL AIR DRAPED ACROSS
THE NORTHERN PORTION OF THE CIRCULATION.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 16W MADE A FAIRLY SHARP WESTWARD TURN OVER
THE PAST SIX HOURS, NOW HEADING WEST-NORTHWEST, ALONG THE
SOUTHWESTERN SIDE OF THE DEEP STR. OVER THE NEXT 24 TO 36 HOURS, TS
16W WILL GRADUALLY COME TO A WESTWARD HEADING AS THE RIDGE BUILDS
WESTWARD TO THE NORTH. TS 16W WILL COME TO AN INFLECTION POINT IN
THE FORECAST AFTER TAU 48, WITH SIGNIFICANT UNCERTAINTY IN THE
TRACK TRAJECTORY AFTER THIS POINT CONTINUING TO MANIFEST ITSELF IN
THE MODEL DATA, FULLY DEPENDENT UPON THE STRENGTH OF THE SYSTEM AT
THAT TIME. IF THE SYSTEM ACTUALLY SUCCEEDS IN ITS CURRENT ATTEMPT AT
VORTEX ALIGNMENT AND SYMMETRIZATION, IT WILL OBTAIN A HIGHER
INTENSITY PRIOR TO THE INFLECTION POINT AND TRAVEL ON A FLATTER
TRAJECTORY TOWARDS THE WEST ROUGHLY BETWEEN 20N-22N. ON THE OTHER
HAND, IF TS 16W FAILS IN THIS SECOND ATTEMPT TO SYMMETRIZE, THEN IT
WILL REMAIN SIGNIFICANTLY WEAKER THROUGH UP TO TAU 48, AND TRAVEL
ON A MORE NORTHWESTWARD TRACK GENERALLY TOWARDS THE RYUKYU CHAIN.
ADDITIONAL DETAILS OF THE MODEL LAYDOWN WILL BE DISCUSSED IN THE
NEXT SECTION. THE CURRENT FORECAST REMAINS CONSISTENT WITH THE
PREVIOUS ONE AND ASSUMES THE SYSTEM IS ULTIMATELY SUCCESSFUL IN
INTENSIFYING TO TYPHOON STRENGTH BY TAU 48, HOWEVER THIS WILL
LIKELY OCCUR IN FITS AND STARTS, HENCE THE SLOW PACE OF
INTENSIFICATION. AT TAU 48, THE SYSTEM MOVES UNDER A STRONG BAND OF
NORTHEASTERLY FLOW, NEAR JET STRENGTH IN SOME MODELS. A STRONGER
SYSTEM, OR ONE POSITIONED A BIT FURTHER SOUTH, WILL BE ABLE TO FEND
OFF THE ENHANCED SHEAR ASSOCIATED WITH THESE HIGHER NORTHEASTERLY
WINDS, WHILE A WEAKER STORM WILL NOT. THE JTWC FORECAST CALLS FOR A
STEADY INTENSITY THROUGH TAU 72, THOUGH THE SYSTEM MAY VERY WELL
WEAKEN DURING THIS PERIOD. AFTER TAU 72, THE SHEAR BEGINS TO
DECREASE ALONG THE FLATTER TRACK OF THE JTWC FORECAST, ALLOWING FOR
REINTENSIFICATION. ON THIS PATH, THE ACTUAL PEAK INTENSITY WILL
LIKELY OCCUR PRIOR TO LANDFALL IN TAIWAN AND IS NOT DIRECTLY
CAPTURED IN THE FORECAST. AFTER LANDFALL, THE SYSTEM RAPIDLY
WEAKENS DUE TO INTERACTIONS WITH THE RUGGED TERRAIN. FOR A WEAKER
SYSTEM ON A MORE NORTHWESTWARD PATH, THE INCREASED SHEAR AND DRY
AIR WILL RESULT IN A FASTER PACE OF WEAKENING THROUGH THE FORECAST
PERIOD.
MODEL DISCUSSION: THERE CONTINUES TO BE A CONSIDERABLE AMOUNT OF
UNCERTAINTY IN BOTH THE DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE,
AS WELL AS IN THE INTENSITY GUIDANCE. THE DETERMINISTIC CONSENSUS
PACKAGE SHOWS INCREASED DISPERSAL IN THE AGGREGATE, THOUGH SOME
INDIVIDUAL MODELS ARE FLIP-FLOPPING NORTH AND SOUTH OVER THE PAST
COUPLE OF RUNS, PARTICULARLY THE ECWMF AND THE GFS WHICH JUMPED FAR
TO THE NORTH AT 06Z BUT HAVE NOW CROSSED BACK TO THE SOUTH OF THE
CONSENSUS. OVERALL, CROSS-TRACK UNCERTAINTY INCREASES TO 300NM BY
TAU 72, BETWEEN THE EGRR AND GEFS MEAN ON THE NORTH SIDE, AND THE
GALWEM AND JGSM ON THE SOUTHERN EDGE. BY TAU 120, THE MODELS
CONTINUE TO FAN OUT, WITH NAVGEM LYING NEAR SASEBO WHILE THE GALWEM
IS POSITIONED ON THE CHINESE COAST WEST OF TAIWAN. THE ECMWF, ECMWF
ENSEMBLE, ECMWF-AIFS, UKMET ENSEMBLE, AND JGSM ARE POSITIONED SOUTH
OF THE CONSENSUS MEAN, WHILE THE GFS, GEFS, NAVGEM, AND EGRR ARE ON
THE NORTH SIDE. THE JTWC FORECAST IS POSITIONED NEAR THE ECMWF AND
ECENS MEAN THROUGH THE FORECAST PERIOD. INTENSITY GUIDANCE IS A
MIXED BAG WITH EXTREME UNCERTAINTY AND RANGE OF POTENTIAL OUTCOMES.
THE MESOSCALE MODELS ARE PEAKING BETWEEN 80-110 KNOTS, WHILE THE
DECAY-SHIPS AND CONSENSUS ARE HOVERING NEAR 65-70 KNOTS. LASTLY,
THE RICN, RIDE AND CTR1 RI AIDS CONTINUE TO TRIP, BRINGING THE
SYSTEM TO 110 KNOTS WITHIN 48 HOURS. THE JTWC FORECAST IS PLACED
CLOSE TO THE CONSENSUS MEAN THROUGH TAU 72, THEN BREAKS 10 KNOTS
HIGHER AT TAU 96 IN LIGHT OF THE CTCX, COTC, AND EVEN THE ECMWF
WHICH SHARPLY INTENSIFY THE SYSTEM PRIOR TO LANDFALL IN TAIWAN TO
BETWEEN 90-110 KNOTS. AS MENTIONED, THE ACTUAL PEAK WILL LIKELY
OCCUR BETWEEN TAU 96 AND LANDFALL.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
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楼主: ygsj24
发表于 2025-8-8 23:00
