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发表于 2025-11-30 10:41
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JTWC/33W/#22/11-30 00Z Prognostic Reasoning
WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (KOTO) WARNING NR
022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 14.0N 112.4E
INITIAL INTENSITY: 50 KTS
GEOGRAPHIC REFERENCE: 266 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 17 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS MODERATE
CONVECTION BEGINNING TO REDEVELOP NEAR THE ASSESSED LOW LEVEL
CIRCULATION CENTER (LLCC), AND WELL-DEFINED SPIRAL BANDING FEATURES
WRAPPING INTO THE OBSCURED LLCC. A 292221Z SSMIS 91GHZ MICROWAVE
IMAGE REVEALS FRAGMENTED CONVECTION ISOLATED TO THE EASTERN FLANK
OF THE CIRCULATION AND SHALLOW SPIRAL BANDS ON THE WESTERN FLANK, A
REVERSAL IN THE OVERALL STRUCTURAL ORIENTATION COMPARED TO 24 HOURS
AGO. ANIMATED WATER VAPOR AND CIMSS ATMOSPHERIC MOTION VECTORS
(AMVS) DEPICT AN AREA OF DEEP, DRY AIR MOVING IN FROM THE NORTHWEST
AND BEGINNING TO IMPINGE ON THE OUTER FRINGES OF TS 33W, ALONG WITH
A BROAD ARC OF OUTFLOW PUSHING WELL OUT TO THE SOUTHEAST. THE
INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN
EXTRAPOLATION OF THE LLCC REVEALED IN THE MICROWAVE IMAGE NOTED
ABOVE AND ON TOP OF A VERY TIGHT GROUPING OF AGENCY FIX POSITIONS.
THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A
BLEND OF THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED
BELOW. ENVIRONMENTAL CONDITIONS ARE MARGINAL, WITH COMPETING
INFLUENCES. SHEAR IS LOW, BUT OUTFLOW IS WEAK, WHILE DRY AIR IS
BEGINNING TO INTRUDE UPON THE NORTHWESTERN SIDE OF THE SYSTEM AND
SSTS REMAIN RELATIVELY COOL DUE TO CONTINUED UPWELLING DUE TO THE
VERY SLOW MOVEMENT OF THE SYSTEM.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, WITH THE
STRONGEST INFLUENCE COMING FROM THE SUBTROPICAL RIDGE (STR)
DEVELOPING OVER LUZON.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T3.5 - 55 KTS
RCTP: T3.0 - 45 KTS
KNES: T3.5 - 55 KTS
CIMSS SATCON: 48 KTS AT 292300Z
CIMSS ADT: 47 KTS AT 300030Z
CIMSS AIDT: 37 KTS AT 300030Z
CIMSS D-MINT: 44 KTS AT 292221Z
CIMSS D-PRINT: 45 KTS AT 300020Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 26-27 CELSIUS
OUTFLOW: WEAK RADIAL
OTHER FACTORS: DRY AIR MOVING IN FROM THE NORTHWEST, UPWELLING
OF COOLER WATERS.
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
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 STORM (TS) 33W IS STILL CREEPING
NORTHWARD, STUCK IN A WEAK AND COMPETING STEERING PATTERN, WITH
RIDGING DEVELOPING OVER LUZON AND A RIDGE OVER SOUTHERN MYANMAR.
THE RIDGING OVER LUZON IS STRENGTHENING AND SLOWLY IMPARTING A
GREATER INFLUENCE ON THE TRACK OF TS 33W AND THIS TREND IS EXPECTED
TO CONTINUE FOR THE NEXT 12 TO 24 HOURS. ONE MAJOR CHANGE TO THE
FORECAST OF THIS RIDGE IS THAT IT IS NOW EXPECTED TO PUSH WESTWARD
SOONER THAN PREVIOUSLY EXPECTED. THIS WILL PUSH TS 33W ONTO A
WESTWARD TRACK EARLIER THAN THE PREVIOUS FORECAST, NOW EXPECTED TO
REACH ITS FURTHEST NORTHWARD POINT WITHIN THE NEXT 12 HOURS, THEN
TURN SHARPLY WESTWARD. AT THE SAME TIME, THE RIDGE OVER MYANMAR
WILL BUILD AND SHIFT EASTWARD, MERGING WITH THE RIDGE OVER THE
SOUTH CHINA SEA (SCS) WITHIN 24 HOURS. THE STEERING INFLUENCE THEN
QUICKLY SHIFTS TO THE WESTERN RIDGE, AND TS 33W WILL TURN SHARPLY
SOUTHWESTWARD SHORTLY AFTER TAU 24. THE SYSTEM WILL THEN SLOWLY
PICK UP SPEED AS IT TRACKS TOWARDS THE COAST OF VIETNAM, WHERE
LANDFALL IS EXPECTED SHORTLY AFTER TAU 72. COMPETING ENVIRONMENTAL
PARAMETERS (LOW SHEAR, BUT WEAK UPPER-LEVEL OUTFLOW, MODESTLY WARM
SSTS AND ENHANCED DRY AIR INTRUSION FROM THE NORTHWEST) WILL RESULT
IN A STEADY INTENSITY THROUGH TAU 36, THOUGH SLIGHT DEVIATIONS BOTH
HIGHER AND LOWER ARE POSSIBLE. AFTER TAU 36 HOWEVER, RAPIDLY
INCREASING SHEAR, DRY AIR ENTRAINMENT INTO THE CORE OF THE SYSTEM
AND REDUCED SSTS WILL CONSPIRE TO WEAKEN THE SYSTEM RAPIDLY AS IT
APPROACHES LANDFALL. THE SYSTEM WILL BE A MINIMAL TROPICAL
DEPRESSION AS IT MOVES ASHORE IN VIETNAM AND DISSIPATE OVER LAND
SHORTLY THEREAFTER.
MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GENERAL
AGREEMENT IN THE SHORT-TERM, WITH ALL MEMBERS OF THE GUIDANCE
PACKAGE SHOWING A TRACK NORTHWARD THROUGH TAU 12 FOLLOWED BY A
SHARP TURN WEST THEN SOUTHWEST. HOWEVER, THEY DO DIFFER STRONGLY ON
THE PACE OF ACCELERATION AFTER THE TURN, AND BOTH ALONG- AND
CROSS-TRACK SPREAD OPEN UP RAPIDLY AFTER TAU 36. BY TAU 48, CROSS-
AND ALONG-TRACK UNCERTAINTY BOTH OPEN UP TO ABOUT 150NM. BY TAU 72,
ALONG-TRACK SPREAD INCREASES TO ABOUT 300NM BETWEEN NAVGEM WHICH IS
SITUATED OVER CAMBODIA AND THE GEFS MEAN JUST OFFSHORE OF VIETNAM,
WHILE ALONG-TRACK SPREAD INCREASES TO ABOUT 275NM BETWEEN NAVGEM
AND THE MUCH SLOWER GFS, ALONG OFFSHORE OF VIETNAM. UNCERTAINTY
INCREASES STILL FURTHER THROUGH THE END OF THE FORECAST AS THE
MODELS BEGIN TO LOSE TRACK OF THE VORTEX. THE JTWC FORECAST IS
POSITIONED CLOSE TO THE ECMWF ENSEMBLE MEAN WITH MEDIUM TO LOW
CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT, WITH ALL
GUIDANCE SAVE FOR THE DECAY-SHIPS (BOTH GFS AND NAVGEM) INDICATING
STEADY INTENSITY FOR ABOUT THE FIRST 24 HOURS OR SO FOLLOWED BY A
GENERAL WEAKENING TREND THEREAFTER. THE JTWC FORECAST IS PLACED
NEAR THE CONSENSUS MEAN 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 05:57
