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发表于 2025-8-20 22:50
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JTWC/18W/#06/08-20 12Z Prognostic Reasoning
WDPN32 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (EIGHTEEN)
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 31.2N 128.0E
INITIAL INTENSITY: 35 KTS
GEOGRAPHIC REFERENCE: 143 NM SOUTHWEST OF SASEBO, JAPAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION (LLC), WITH FLARING DEEP
CONVECTION OVER THE EASTERN QUADRANT. A 201008Z GMI 89GHZ MICROWAVE
IMAGE REVEALS A SYMMETRIC, DEFINED LLC, WITH A CLUSTER OF
DISORGANIZED DEEP CONVECTION OVER THE EASTERN QUADRANT. A 201136Z
ASCAT-B BULLSEYE IMAGE INDICATES AN ELONGATED CENTER AND SMALL REGION
OF ELEVATED WINDS (30-35 KNOTS) ASSOCIATED WITH THE DEEP CONVECTION,
WITH AN ISOLATED 40 KNOT WIND. THE INITIAL POSITION AND INITIAL
INTENSITY ARE BASED ON THE ASCAT IMAGE WITH HIGH CONFIDENCE.
ENVIRONMENTAL CONDITIONS ARE MARGINAL, WITH FAIR OUTFLOW OFFSET BY
DRY AIR ENTRAINMENT.
INITIAL WIND RADII BASIS: SCATTEROMETER DATA
CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST AND SOUTHEAST, ORIENTED SSW TO NNE.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T1.5 - 25 KTS
KNES: T1.5 - 25 KTS
CIMSS ADT: 34 KTS AT 201130Z
CIMSS AIDT: 40 KTS AT 201130Z
CIMSS D-MINT: 27 KTS AT 201008Z
CIMSS D-PRINT: 28 KTS AT 201210Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
VWS: 15-20 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE EASTWARD
OTHER FACTORS: DRY AIR ENTRAINMENT
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: TROPICAL STORM (TS) 18W IS FORECAST TO TRACK
NORTH-NORTHEASTWARD TO EAST-NORTHEASTWARD THROUGH THE FORECAST PERIOD
AS IT ROUNDS THE NORTHWESTERN PERIPHERY OF THE STR. UPPER-LEVEL
CONDITIONS HAVE IMPROVED STEADILY OVER THE PAST DAY AS THE SYSTEM
TRACKED AWAY FROM AN UPPER-LEVEL LOW NEAR TAIWAN, WITH IMPROVED
EQUATORWARD OUTFLOW EVIDENT IN THE ANIMATED WATER VAPOR RGB IMAGERY.
ADDITIONALLY, EASTWARD OUTFLOW HAS MAINTAINED. HOWEVER, DRY AIR
ENTRAINMENT THROUGH THE COLUMN HAS CONTINUED TO HINDER ANY
SIGNIFICANT CONSOLIDATION. THERE IS A VERY SHORT WINDOW
(APPROXIMATELY SIX HOURS) FOR THE SYSTEM TO MAINTAIN 35 KNOTS UNTIL
VERTICAL WIND SHEAR INCREASES TO HIGH (25-45 KNOTS) LEVELS AND DRY
AIR OVERWHELMS THE SYSTEM.
MODEL DISCUSSION: JTWC TRACK CONFIDENCE IS MEDIUM, WITH INCREASING
UNCERTAINTY IN THE EXACT TRACK AFTER TAU 12. IN LARGE PART, THIS IS
DUE TO THE WEAK NATURE OF THE SYSTEM AND THE COMPLEX LOW-LEVEL
STEERING INFLUENCE AS IT WEAKENS NEAR LANDFALL. THE CURRENT SUITE OF
DETERMINISTIC GUIDANCE SHOWS A SPREAD FROM WESTERN CENTRAL KYUSHU TO
NORTHERN KYUSHU. THE 200000Z ECMWF ENSEMBLE (ECENS) RUN SHOWS THE
BULK OF THE SOLUTIONS TRACKING THE SYSTEM INTO THE KOREAN STRAIT AND
NORTHERN KYUSHU. THE 200600Z GFS ENSEMBLE (GEFS) IS SIMILAR, WITH A
WIDER SPREAD OF SOLUTIONS FROM THE KOREAN STRAIT TO SOUTHERN KYUSHU.
OVERALL, BOTH ENSEMBLES INDICATE THAT A POTENTIAL DIRECT TRACK OVER
CHEJU-DO AND THE BUSAN AREA IS AT A VERY LOW PROBABILITY. RELIABLE
INTENSITY GUIDANCE INDICATES A PEAK INTENSITY OF 35-45 KNOTS OVER THE
NEXT 12 HOURS, WITH UNANIMOUS AGREEMENT ON A SHARP WEAKENING TREND
AFTER TAU 12. HOWEVER, THE LATEST HAFS-A RUN IS FORMING SPURIOUS LOW
PRESSURE AREAS UNDER THE DEEP CONVECTIVE BURSTS, WITH INFLATED 40-45
KNOT WINDS ISOLATED DIRECTLY TO THESE REGIONS.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM//
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楼主: yhh
发表于 2025-8-20 16:01
