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JTWC/05W/#15/07-07 12Z Prognostic Reasoning
WDPN32 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (DANAS) WARNING NR
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 27.1N 121.7E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 120 NM NORTH OF TAIPEI, TAIWAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 18 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES A
FRAGMENTED AND BROAD LOW-LEVEL CIRCULATION (LLCC) OF TROPICAL STORM
(TS) 05W (DANAS). THE INITIAL POSITION IS ASSIGNED WITH LOW
CONFIDENCE BASED ON LOW LEVEL FLOW PRESENT IN EIR, IN CONJUNCTION WITH
VAGUELY INDICATED LLCC IN RADAR IMAGERY. ENVIRONMENTAL ANALYSIS
REVEALS LOW (0-5 KTS) VERTICAL WIND SHEAR (VWS), WARM (28-29 C) SEA
SURFACE TEMPERATURES (SST), DEEP-LAYER MOISTURE, AND MODERATE UPPER-
LEVEL OUTFLOW. WITH THE VORTEX CURRENTLY POSITIONED WITHIN A FAVORABLE
ENVIRONMENT, DEEP CONVECTION IS SLOWLY CONSOLIDATING WITHIN SPIRAL
BANDS WRAPPING INTO A BROAD LLCC. THE INITIAL INTENSITY OF 45 KTS IS
ESTIMATED WITH MEDIUM CONFIDENCE, DERIVED FROM A BLEND OF AGENCY
DVORAK AND OBJECTIVE FIXES DETAILED BELOW.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT -
NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTHEAST AND BUILDING SUBTROPICAL
RIDGE (STR) TO THE NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T3.0 - 45 KTS
RCTP: T2.5 - 35 KTS
KNES: T3.0 - 45 KTS
DEMS: T3.0 - 45 KTS
CIMSS SATCON: 52 KTS AT 071036Z
CIMSS ADT: 57 KTS AT 071130Z
CIMSS AIDT: 53 KTS AT 071130Z
CIMSS D-MINT: 33 KTS AT 071039Z
CIMSS D-PRINT: 31 KTS AT 071230Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 0-5 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: LOW
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 05W HAS SIGNIFICANTLY SLOWED DOWN SINCE
LAST FORECAST AS A RESULT OF A BUILDING STR TO THE NORTHEAST, AND
OCCURRING EARLIER THAN ANTICIPATED SHIFT IN THE STEERING ENVIRONMENT.
TS DANAS IS HOWEVER STILL FORECAST TO CONTINUE ON A NORTHEASTWARD
TRACK ALONG THE NORTHWESTERN PERIPHERY OF A NER TO THE SOUTHEAST,
UNTIL THE RIDGE TO THE NORTH BUILDS ENOUGH TO STEER THE SYSTEM
WESTWARD. AS A RESULT, THE SYSTEM IS EXPECTED TO MAKE LANDFALL OVER
CHINA AROUND TAU 24. POST LANDFALL, THE SYSTEM IS FORECAST TO TRACK
WEST-SOUTHWESTWARD OVER LAND AND DISSIPATE BY TAU 72. TS 05W IS
FORECAST TO MAINTAIN INTENSITY AROUND 45 KTS UNTIL LANDFALL, AS A
RESULT OF COMPETING IMPACT OF MARGINALLY FAVORABLE ENVIRONMENT AND
LAND INTERACTION WITH THE EXTENDED PORTION OF THE VORTEX AND THE
ASSOCIATED WIND FIELD. THEREAFTER, A GRADUAL WEAKENING PHASE AND
EVENTUAL DISSIPATION BY TAU 72 ARE ANTICIPATED.
MODEL DISCUSSION: NUMERICAL TRACK MODEL GUIDANCE EXHIBITS FAIR
AGREEMENT THROUGHOUT THE FORECAST PERIOD, DEMONSTRATED BY A
CROSS-TRACK SPREAD OF APPROXIMATELY 30 NM AT LANDFALL, AMONG MAJORITY
OF THE MULTI-MODEL CONSENSUS MEMBERS. MAJOR OUTLIERS TO THIS GUIDANCE
ARE GFS AND GFS ENSEMBLE, WHICH PREDICT A NEARLY FULL U-TURN AROUND
TAU 24, RESULTING IN A SOUTHWESTWARD TRACK ALONG THE COASTLINE OF
CHINA. INTENSITY GUIDANCE HOWEVER IN CONSISTENT AMONG NEARLY ALL
CONSENSUS MEMBERS, INDICATING WEAKENING TREND BEGINNING BETWEEN
TAUS 24 AND 36, ALIGNING WITH THE LANDFALL TIMELINE. ONE OUTLIER
IN THIS INSTANCE IS THE GUIDANCE FROM COAMPS-TC, WHICH PREDICTS
SLIGHT INTENSIFICATION THROUGH TAU 36, WITH THE SYSTEM REACHING
50-55 KTS PRIOR TO LANDFALL. ADDITIONALLY, SOME MODELS, LIKE GFS,
INDICATE THAT THE SYSTEM WILL LINGER AROUND 30 KTS BEYOND TAU 72,
LIKELY DUE TO ITS CURRENT ASSOCIATED TRACK ASSESSMENT MUCH CLOSER
TO THE TAIWAN STRAIT, AS COMPARED TO OTHER AVAILABLE GUIDANCE. JTWC
TRACK AND INTENSITY PREDICTIONS ARE THEREFORE ASSESSED WITH MEDIUM
CONFIDENCE AND ARE LAID CLOSE TO THE MULTI-MODEL CONSENSUS.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM//
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楼主: 理可的呆萌呆毛
发表于 2025-7-7 17:41
发表于 2025-7-7 18:02
