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JTWC/04W/#23/04-14 12Z Prognostic Reasoning
WDPN31 PGTW 141500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 14.9N 145.8E
INITIAL INTENSITY: 125 KTS
GEOGRAPHIC REFERENCE: 18 NM SOUTH OF SAIPAN
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 45 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SLOWLY
WEAKENING TYPHOON UNDERGOING AN EYEWALL REPLACEMENT CYCLE (ERC).
WHILE THE CENTRAL DENSE OVERCAST (CDO) HAS BECOME MORE RAGGED, THE
CONVECTION REMAINS HEALTHY, WITH CLOUD TOP TEMPERATURES AS COLD AS
-80 DEGREES CELSIUS. THE CONVECTION IS NOW PRIMARILY WRAPPING
AROUND THE OUTER EYEWALL WITH THE INNER EYEWALL ERODING AWAY, WHICH
IS CLEARLY SHOWCASED BY A 140821Z WSF-M MWI 89 GHZ IMAGE. THE PGUA
RADAR CONFIRMS THAT THE INNER EYEWALL IS SHALLOWING OUT AND OPENING
UP, ENABLING A GRADUAL OUTWARD TRANSFER OF MOMENTUM TO THE
CONSOLIDATING OUTER EYEWALL. FOR 141200Z, THE RADIUS OF MAXIMUM
WIND WILL REMAIN ALIGNED WITH THE INNER EYEWALL, GIVEN THAT SAIPAN
INTERNATIONAL AIRPORT IS REPORTING EVEN HIGHER WIND SPEEDS INSIDE
THE OUTER RING. IN FACT, THE AIRPORT SENSOR REPORTED A SUSTAINED
WIND OF 71 KTS AND A GUST OF 113 KTS AT 141200Z, AND EARLIER
METAR RETURNED A MEAN SEA LEVEL PRESSURE OF 948.8 MB. ENVIRONMENTAL
CONDITIONS ARE FAVORABLE WITH AMPLE OCEAN HEAT CONTENT OF NEAR 150
KJ CM2, ABUNDANT DEEP-LAYER MOISTURE, AND LOW VERTICAL WIND SHEAR
(VWS), THOUGH THE ONGOING ERC IS LEADING TO SOME WEAKENING. THE
UPPER-LEVEL OUTFLOW REMAINS ROBUST IN THE WESTERN SEMICIRCLE BUT IS
SOMEWHAT RESTRICTED IN THE SOUTHEAST QUADRANT. THE FORWARD SPEED OF
TYPHOON 04W HAS SIGNIFICANTLY SLOWED TO 04 KTS, PROLONGING THE
DESTRUCTIVE CONDITIONS OVER THE MARIANA ISLANDS. AFTER A BRIEF
WEST-NORTHWEST MOTION, SINLAKU APPEARS TO HAVE RESUMED ITS AVERAGE
TRAJECTORY TOWARDS THE NORTHWEST, AND THE WESTERN EYEWALL HAS MOVED
OVER SAIPAN AND TINIAN. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE WELL-DEFINED EYE IN THE EIR AND RADAR
IMAGERY. THE INITIAL INTENSITY IS SET AT 125 KTS WITH MEDIUM
CONFIDENCE BASED ON A BLEND OF THE T6.0-T7.0 DVORAK FIXES FROM
PGTW, KNES, RJTD, AND RCTP.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.5 - 127 KTS
RJTD: T7.0 - 140 KTS
RCTP: T7.0 - 140 KTS
KNES: T6.0 - 115 KTS
CIMSS ADT: 119 KTS AT 141140Z
CIMSS AIDT: 114 KTS AT 141140Z
CIMSS D-PRINT: 121 KTS AT 141140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 0-5 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
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: TY 04W WILL CONTINUE TO SLOWLY TRAVEL TOO THE
NORTHWEST UNDER THE STEERING INFLUENCE OF THE BUILDING NEAR TO THE
EAST. AS SINLAKU GAINS LATITUDE AND APPROACHES A WEAKNESS IN THE
SUBTROPICAL RIDGE (STR) TO THE NORTH, IT WILL BEGIN ROUND THE STR AXIS
BY TAU 24. A SHARPENING SHORTWAVE TROUGH PASSING SOUTH OF HONSHU WILL
BRIEFLY ERODE THE STR, ALLOWING FOR A MORE NORTHWARD TO NORTH-
NORTHEASTWARD MOTION AND A GRADUAL INCREASE IN FORWARD SPEED. BY TAU
72, THE SYSTEM WILL BECOME INCREASINGLY EMBEDDED IN THE WESTERLIES
POLEWARD OF THE STR AXIS, ACCELERATE TOWARDS THE NORTHEAST, AND
UNDERGO EXTRATROPICAL TRANSITION (ETT) AS A STORM-FORCE LOW. THE
POWERFUL TYPHOON CONTINUES TO SLOWLY WEAKEN DUE TO THE ERC. FOR THE
NEXT 24 HOURS, ENVIRONMENTAL CONDITIONS WILL BE CONDUCIVE DUE TO LOW
VWS, WARM SEA SURFACE TEMPERATURES (SST), AND AMPLE MID-LEVEL
MOISTURE. IF THE SYSTEM IS ABLE TO QUICKLY COMPLETE THE ERC, THE
INTENSITY WILL HOLD, AND SLIGHT INTENSIFICATION IS NOT OUT OF THE
QUESTION. THE FORECAST INTENSITY REFLECTS A SCENARIO IN WHICH THE ERC
WILL BE SLOW TO COMPLETE, AND THE INITIAL RATE OF WEAKENING WILL BE
SLOW. ENVIRONMENTAL ANALYSIS DEPICTS A VAST REGION OF DRY AIR
IMMEDIATELY WEST OF THE STORM. FASTER WEAKENING WILL COMMENCE BEYOND
TAU 24 AS TY 04W TRAVERSES OVER PROGRESSIVELY COOLER SST AND ENTERS A
DRIER, MORE STABLE ENVIRONMENT WITH A SIGNIFICANTLY LARGER EYE.
MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, MODELS ARE IN FAIR
AGREEMENT FOR THE FIRST 48 HOURS. THE CROSS-TRACK SPREAD INCREASES
FROM 55 NM AT TAU 24 TO 100 NM AT TAU 48, THOUGH A LARGE MAJORITY
OF MODELS ARE GROUPED TIGHTLY WITHIN THE CENTER OF THE UNCERTAINTY
ENVELOPE. GREATER SPREAD ARISES AT THE LATER TAUS BECAUSE
DIFFERENCES IN HOW THE MODELS HANDLE THE EVOLUTION OF THE TROUGHS
PASSING NORTH OF THE STR AND THE STRENGTH OF THE STR SHAPE THE
AMOUNT OF RECURVATURE IN THE TRACK. THE JTWC FORECAST TRACK IS LAID
WITH HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM CONFIDENCE
THEREAFTER, ALIGNING CLOSELY WITH THE GROUPING CONSISTING OF
HAFS-A, THE GFS ENSEMBLE MEAN, ECMWF, AND GALWEM. THE INTENSITY
FORECAST IS SET CLOSE TO HAFS-A AND THE MULTI-MODEL CONSENSUS IN
DEPICTING SLOW INITIAL WEAKENING FOLLOWED BY STEADY WEAKENING
THROUGH THE REMAINDER OF THE FORECAST PERIOD. COAMPS-TC AND GFS
DEPICT RAPID WEAKENING, THE SOLUTIONS OF WHICH ARE DISCOUNTED AS
BEING UNREALISTIC GIVEN THE FAVORABLE CONDITIONS.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
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楼主: ygsj24
发表于 2026-4-14 23:10
