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发表于 2025-11-30 05:01
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JTWC/33W/#21/11-29 18Z Prognostic Reasoning
WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (KOTO) WARNING NR
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 13.7N 112.2E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 265 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 02 KTS
SIGNIFICANT WAVE HEIGHT: 15 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 33W WITH A WEAK, COMPACT INNER-CORE OF MODERATE
CONVECTION, WITH WEAKER CONVECTION FORMING INTO BANDS THAT ARE
WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). EARLIER
ASCAT AND SAR PASSES INDICATE THAT THE LLCC REMAINS SMALL BUT
WELL-DEFINED AND IS DRIFTING SLOWLY NORTHWARD. THE INITIAL POSITION
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN EXTRAPOLATION OF THE
EARLIER ASCAT DATA ALONG WITH ANALYSIS OF THE EIR. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED TOWARDS THE
LOWER END OF THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES IN
LIGHT OF THE LOW (40 KNOT) SAR AND ASCAT MEASUREMENTS. WATER VAPOR
IMAGERY AS WELL AS THE EIR AND HIGH-RESOLUTION MODEL CROSS-SECTION
SUGGEST THAT THE ENVIRONMENT HAS MOISTENED OVERNIGHT, ESPECIALLY IN
THE EASTERN FLANK, THROUGH SOME RESIDUAL MID-LEVEL DRY AIR IS STILL
EVIDENT IN THE SOUTHEASTERN PORTION OF THE CIRCULATION. CIRA
DERIVED MOTION VECTOR (DMV) UPPER-LEVEL ANALYSIS SUPPORTED BY WATER
VAPOR IMAGERY, INDICATES A BURST OF RADIAL OUTFLOW EMANATING
OUTWARD FROM THE CENTER, THOUGH AT PRESENT IT REMAINS RELATIVELY
WEAK. SHEAR HAS DROPPED SIGNIFICANTLY OVER THE PAST SIX HOURS AS
THE OUTFLOW HAS IMPROVED, WITH THE LATEST CIMSS SHEAR ESTIMATES
DOWN TO 5-7 KNOTS. ADDITIONALLY, THE SYSTEM IS MOVING FURTHER AWAY
FROM THE UPWELLING INDUCED COLD-POOL AND INTO WARMER WATERS.
INITIAL WIND RADII BASIS: PERSISTENCE WITH EARLIER SAR DATA
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF AN EXTENSION OF
THE DEEP-LAYER SUBTROPICAL RIDGE (STR) OVER LUZON.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T3.5 - 55 KTS
RCTP: T3.5 - 55 KTS
KNES: T3.5 - 55 KTS
DEMS: T3.0 - 45 KTS
CIMSS SATCON: 50 KTS AT 291830Z
CIMSS ADT: 47 KTS AT 291730Z
CIMSS AIDT: 36 KTS AT 291730Z
CIMSS D-MINT: 42 KTS AT 291439Z
CIMSS D-PRINT: 40 KTS AT 291830Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 26-27 CELSIUS
OUTFLOW: WEAK RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
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 33W HAS DRIFTED SLOWLY NORTHWARD OVER THE
LAST 24 HOURS, AND CONTINUES TO DO SO, AS IT REMAINS TRAPPED IN A
COMPETING STEERING PATTERN, WITH RIDGING DEVELOPING OVER LUZON AND
RIDGING OVER SOUTHERN MYANMAR. THIS GENERAL SETUP IS EXPECTED TO
PERSIST FOR ABOUT ANOTHER 24 HOURS AND THE SYSTEM WILL CONTINUE TO
PUSH NORTHWARD AT ABOUT 2 KNOTS DURING THIS PERIOD. BY THIS POINT
IN THE FORECAST, THE RIDGE PATTERN BEGINS TO SHIFT. FIRST THE RIDGE
OVER LUZON PUSHES WESTWARD WHICH WILL HAVE THE EFFECT OF GIVING TS
33W A GENTLE NUDGE TOWARDS THE WEST AT TAU 36. THEN THE RIDGE OVER
MYANMAR SHIFTS EASTWARD, BUILDS AND BECOMES THE DOMINATE STEERING
INFLUENCE BY TAU 48. TS 33W REACHES THE INFLECTION POINT IN ITS
TRACK AT TAU 24, SHIFTS WEST TO TAU 36 AND THEN TURNS SOUTHWEST
BETWEEN TAU 36 AND TAU 48. THE SYSTEM ACCELERATES SOUTHWESTWARD
THROUGH THE REMAINDER OF THE FORECAST PERIOD, MAKING LANDFALL ALONG
THE SOUTHEASTERN COAST OF VIETNAM BETWEEN TAU 72 AND TAU 96. DUE TO
THE IMPROVING ENVIRONMENTAL CONDITIONS, A BRIEF WINDOW OF
OPPORTUNITY EXISTS FOR TS 33W TO INTENSIFY OVER THE NEXT 24-36
HOURS. WHILE CONDITIONS DO IMPROVE, THEY ARE NOT EXPECTED TO
SUPPORT SIGNIFICANT INTENSIFICATION, PRIMARILY LIMITED BY
RELATIVELY COOL SSTS (WARMER THAN THEY ARE CURRENTLY BUT STILL
HOVERING AROUND 26C-27C). THE SYSTEM WILL PEAK OUT BETWEEN 50-55
KNOTS BY TAU 24, THEN HOVER AT THAT INTENSITY FOR ABOUT 12 HOURS
BEFORE BEING SHELLACKED BY INCREASING SOUTHEASTERLY SHEAR AND DRY
AIR ENTRAINMENT AS IT MOVES SOUTHWESTWARD TOWARDS LANDFALL. THE
SYSTEM WILL WEAKEN BELOW TROPICAL STORM STRENGTH BY TAU 72, THEN
DISSIPATE OVER SOUTHEASTERN VIETNAM BY TAU 96.
MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE HAS COME INTO BETTER
AGREEMENT OVER THE LAST COUPLE OF RUNS, WITH ALL MODELS NOW
AGREEING ON A NORTHWARD TRACK THROUGH TAU 24, THEN A TURN WEST
FOLLOWED BY A TURN SOUTHWESTWARD. THERE REMAINS SOME DIFFERENCES IN
THE EXACT TIMING OF THE TURNS AND THE AMOUNT OF ACCELERATION AFTER
THE TURN OCCURS, LEADING TO SOME ENHANCED CROSS- AND ALONG-TRACK
SPREAD, PARTICULARLY AFTER TAU 48. BY TAU 72, ALONG-TRACK SPREAD
BETWEEN THE NAVGEM AND THE ECMWF OPENS UP TO 250NM, WITH ROUGHLY
THE SAME AMOUNT OF CROSS-TRACK SPREAD. THESE VALUES INCREASE
FURTHER BY THE END OF THE FORECAST PERIOD, WITH THE GFS AND ECMWF
DEPICTING A MUCH SLOWER TRACK PROGRESSION AS COMPARED TO THE NAVGEM
AND JGSM. THE JTWC FORECAST IS POSITIONED ON A BLEND OF THE ECMWF
ENSEMBLE MEAN AND THE GDM ENSEMBLE MEAN, AND CONSISTENT WITH THE
PREVIOUS FORECASTS. CONFIDENCE IS MEDIUM IN THE NEAR-TERM, TRENDING
TO LOW IN THE EXTENDED FORECAST. INTENSITY GUIDANCE IS IN OVERALL
GOOD AGREEMENT THAT THE SYSTEM WILL INTENSIFY OVER THE NEXT 24-36
HOURS, WITH A RANGE OF PEAK INTENSITIES BETWEEN 45-55 KNOTS. THE
JTWC FORECAST IS PLACED NEAR THE CONSENSUS MEAN THROUGH THE
FORECAST PERIOD WITH MEDIUM CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
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楼主: ygsj24
发表于 2025-11-30 00:35
发表于 2025-11-30 04:07
