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发表于 2026-4-19 16:13
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JTWC/04W/#42/04-19 06Z Prognostic Reasoning
WDPN31 PGTW 190900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (SINLAKU) WARNING NR
042//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 27.6N 151.4E
INITIAL INTENSITY: 50 KTS
GEOGRAPHIC REFERENCE: 248 NM NORTHWEST OF MINAMI TORI SHIMA
MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 20 KTS
SIGNIFICANT WAVE HEIGHT: 30 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 04W (SINLAKU) CONTINUES TOO STEADILY BUT SLOWLY
WEAKEN AS IT TRAVERSES POLEWARD AND BEGINS TO LOSE TROPICAL
CHARACTERISTICS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A PARTIALLY EXPOSED, AND BROAD LOW LEVEL CIRCULATION CENTER
(LLCC). A LARGE REGION OF MODERATE CONVECTION, AND UPPER-LEVEL
CLOUDS FORMS A DEVELOPING DELTA RAIN REGION IN THE NORTHEASTERN
QUADRANT OF THE CIRCULATION, INDICATIVE OF THE EARLY PHASES OF EXTRA-
TROPICAL TRANSITION. ALONG THE WESTERN FLANK, STABLE STRATIFORM
CLOUDS ARE BEING ADVECTED AROUND THE SOUTHERN FLANK AND INTO THE CORE
VORTEX. THE LATEST CIMSS SHEAR ANALYSIS INDICATES A SUBTLE SHIFT IN
THE SHEAR DIRECTION FROM WESTERLY TO SOUTHWESTERLY, WHICH ALIGNS THE
SHEAR VECTOR ALONG THE TRACK. THIS CONGRUENCE LIKELY DELAYS FULL LLCC
EXPOSURE, SUSTAINING WEAK TO MODERATE CONVECTION IN THE NORTHEASTERN
QUADRANT. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE ANIMATED MSI. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE, HEDGED HIGHER THAN THE OBJECTIVE ESTIMATES NOTED BELOW IN
DEFERENCE TO RECENT SAR AND SCATTEROMETER DATA INDICATING A STRONGER
WIND FIELD. THE SYSTEM IS NOW OVER VERY COOL WATERS, EXPERIENCING
SIGNIFICANT SHEAR AND ENGULFED IN DRY AIR. POLEWARD OUTFLOW, WHILE
ROBUST, IS INSUFFICIENT TO OFFSET THE OTHERWISE UNFAVORABLE
ENVIRONMENT.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A LOW- TO
MID-LEVEL RIDGE COMPLEX WHICH EXTENDS FROM NEAR GUAM TO SOUTH OF
THE ALEUTIANS.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T2.0 - 30 KTS
RCTP: T1.5 - 25 KTS
CIMSS SATCON: 39 KTS AT 190336Z
CIMSS ADT: 25 KTS AT 190530Z
CIMSS AIDT: 33 KTS AT 190530Z
CIMSS D-MINT: 34 KTS AT 190541Z
CIMSS D-PRINT: 33 KTS AT 190600Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 25-30 KTS
SST: 21-22 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: DRY MID-LEVEL AIR OVERLAYING THE CIRCULATION.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN TRUNCATED TO 24
HOURS.
FORECAST DISCUSSION: ANALYSIS OF 1000-500MB THICKNESS, 500MB HEIGHTS,
850MB WINDS, SST DATA, AS WELL AS MANUAL AND AUTOMATED PHASE
CLASSIFICATION WORKSHEETS INDICATE TS 04W IS LIKELY A SUBTROPICAL
CYCLONE AT THIS POINT IN TIME; AT BEST A HYBRID TYPE SYSTEM,
CHARACTERIZED BY A HYBRID THERMAL STRUCTURE WITH A STRONG MID-LEVEL
WARM CORE AND SHALLOW VORTEX, MOVING OVER VERY COOL WATERS AND
FORMATIVE THERMAL ADVECTION. THIS PHASE OF THE SYSTEMS LIFE CYCLE
WILL BE SHORT-LIVED HOWEVER AND EXTRA-TROPICAL TRANSITION (ETT) WILL
BEGIN IMMINENTLY. THE SYSTEM IS ACCELERATING NORTHEASTWARD ALONG THE
NORTHWESTERN FLANK OF A SOUTHWEST-NORTHEAST ORIENTED RIDGE WHICH
EXTENDS FROM NEAR GUAM TO SOUTH OF THE ALEUTIAN ISLANDS. THE WESTERN
END OF A OLD FRONTAL BOUNDARY IS SITUATED JUST NORTHEAST OF THE LLCC
AND EXTENDS FAR TO THE EAST. THE NORTHEASTERN PERIPHERY OF THE
CIRCULATION IS ALREADY INTERACTING WITH THE BAROCLINIC ZONE, WITH
ISENTROPIC UPGLIDE FORMING THE DELTA RAIN REGION ALONG THE DEVELOPING
WARM FRONT. OVER THE NEXT 24 HOURS, THE RIDGE WILL SLOWLY FLATTEN OUT
TO A MORE EAST-WEST ORIENTATION, WHILE THE FRONTAL BOUNDARY WILL
BEGIN TO EXERT MORE INFLUENCE, DRIVING TS 04W EASTWARD ALONG THE
BOUNDARY. TS 04W WILL RAPIDLY COMPLETE ET WITHIN THE NEXT 24 TO 30
HOURS AS IT COUPLES WITH THE BAROCLINIC ZONE, INCREASES THERMAL
ADVECTION, AND INTERACTS WITH THE RIGHT ENTRANCE REGION OF THE POLAR
FRONT JET (PFJ). SYNOPTIC-SCALE DIVERGENCE ASSOCIATED WITH THE PFJ
JET STREAK MAY PROVIDE FOR TEMPORARY BAROCLINIC RE-INTENSIFICATION
DURING THE ET PROCESS.
MODEL DISCUSSION: TRACK GUIDANCE IS IN TIGHT CONVERGENCE, WITH
MINIMAL CROSS- OR ALONG-TRACK SPREAD THROUGH THE SHORT FORECAST
PERIOD. THE JTWC FORECAST IS ALIGNED WITH THE CONSENSUS (CONW) MEAN
WITH HIGH CONFIDENCE. INTENSITY GUIDANCE REMAINS BIFURCATED, WITH
SHIPS AND COAMPS-TC (NAVGEM) INDICATING PRECIPITOUS WEAKENING, WHILE
THE HAFS-A, HWRF, COAMPS-TC (GFS) AND GFS DEPICT A MORE CONSERVATIVE
SLOW BUT STEADY WEAKENING SCENARIO. THE JTWC FORECAST IS CONSISTENT
WITH THE HWRF-BASED DECAY RATE WITH HIGH CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: HIGH//
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楼主: ygsj24
发表于 2026-4-19 11:23
