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JTWC/16W/#03/08-07 12Z Prognostic Reasoning
WDPN32 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (SIXTEEN) WARNING NR
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 19.0N 147.0E
INITIAL INTENSITY: 35 KTS
GEOGRAPHIC REFERENCE: 340 NM NORTH-NORTHEAST OF ANDERSEN AFB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 13 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 16W HAS RAPIDLY CONSOLIDATED AND QUALITATIVELY
IMPROVED IN OVERALL STRUCTURAL APPEARANCE OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
IRREGULAR CENTRAL DENSE OVERCAST (CDO) FEATURE, WITH UPPER-LEVEL
CIRRUS FORMING TRANSVERSE BANDS ALONG THE EASTERN SIDE OF THE CDO,
INDICATIVE OF STRONG UPPER-LEVEL OUTFLOW IN THESE REGIONS. ANIMATED
WATER VAPOR IMAGERY AND CIRA DERIVED MOTION VECTOR (DMV) PRODUCTS
CONTINUE TO INDICATE A WEAK TUTT-CELL POSITIONED APPROXIMATELY
450NM NORTHWEST OF TS 16W AND A SECOND TUTT-CELL POSITIONED
APPROXIMATELY 950NM TO THE EAST. UPPER-LEVEL WINDS ARE
NORTHEASTERLY ACROSS THE REGION SURROUNDING TS 16W, BUT THE FLOW
SPLITS NEAR THE SYSTEM, WITH A PORTION HEADING POLEWARD INTO THE
EAST SIDE OF THE TUTT-CELL, AND THE OTHER PORTION HEADING
EQUATORWARD. ADDITIONALLY. A FORTUITOUS 071150Z ASCAT-C BULLSEYE
REVEALED THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS MOVED FURTHER
UNDER THE CDO THAN ORIGINALLY THOUGHT AND PROVIDED HIGH CONFIDENCE
TO THE INITIAL POSITION. THE SAME ASCAT PASS REVEALED 35 KNOT WINDS
IN THE SOUTHEASTERN QUADRANT OF THE ROTATION, CONFIRMING THE PGTW
T2.5 INTENSITY ESTIMATE AS WELL AS THE BULK OF THE OBJECTIVE
INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE,
WITH LOW NORTHEASTERLY VWS, VERY WARM SSTS AND MODERATE EQUATORWARD
AND POLEWARD OUTFLOW.
INITIAL WIND RADII BASIS: SCATTEROMETER DATA
CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T1.5 - 25 KTS
KNES: T2.0 - 30 KTS
CIMSS SATCON: 35 KTS AT 070844Z
CIMSS ADT: 33 KTS AT 071140Z
CIMSS AIDT: 34 KTS AT 071140Z
CIMSS D-MINT: 29 KTS AT 070832Z
CIMSS D-PRINT: 33 KTS AT 071210Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
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: TS 16W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHWESTERN FLANK OF THE STRONG STR OVER
THE NEXT 24 HOURS. THE SYSTEM WILL GRADUALLY TURN ONTO A WESTWARD
TRACK BETWEEN TAU 36 AND TAU 48 AS THE RIDGE BUILDS WESTWARD AND
ULTIMATELY MERGES WITH A SMALL STR CENTERED NEAR OKINAWA, CREATING
A MASSIVE, DEEP, SOUTHWEST-NORTHEAST ORIENTED STR THAT EXTENDS FROM
COASTAL CHINA TO THE DATELINE. TS 16W WILL TRAVEL WESTWARD ALONG
THE SOUTHERN FLANK OF THIS RIDGE THROUGH TAU 72, BEFORE DIPPING
SLIGHTLY SOUTHWESTWARD AROUND TAU 96 AS THE RIDGE MOVES TO A
POSITION SOUTHEAST OF HONSHU. AFTER TAU 96, TS 16W WILL BEGIN
TRACKING MORE WEST-NORTHWESTWARD DUE TO SLIGHT CHANGES IN THE
ORIENTATION OF THE RIDGE AS IT CONTINUES TO MOVE TOWARDS THE WEST.
TS 16W HAS ALREADY INTENSIFIED MORE THAN ORIGINALLY EXPECTED BY
THIS TIME IN THE FORECAST. UNFORTUNATELY, THE LACK OF RECENT
MICROWAVE IMAGERY PRECLUDES A CONCRETE ANALYSIS OF THE LOW-LEVEL
STRUCTURE, WHICH IS OBSCURED UNDER THE CDO. THE ASCAT PASS WOULD
SUGGEST THE LOW-LEVEL VORTEX HAS BECOME BETTER ALIGNED. HOWEVER,
ASSUMING THIS IS TRUE, THE SYSTEM SHOULD BE ABLE TO STEADILY
INTENSIFY OVER THE NEXT 24-48 HOURS. A FASTER RATE OF INTENSIFICATION
IS FORECAST AFTER TAU 48 AS THE SYSTEM MOVES OVER A POOL OF RELATIVELY
HIGH OHC WATERS. WHILE DEEP-LAYER SHEAR IS EXPECTED TO INCREASE
SLIGHTLY BEGINNING AS EARLY AS TAU 48, THE SYSTEM AT THAT POINT SHOULD
BE STRONG ENOUGH TO RESIST, AT LEAST FOR ABOUT 24 HOURS. BEGINNING
AROUND TAU 72, SHEAR IS EXPECTED TO INCREASE SHARPLY (UP TO ABOUT 25-
30 KTS), AND BE ACCOMPANIED BY DRY AIR INTRUSION. THE COMBINATION OF
FACTORS WILL PUT A LID ON INTENSIFICATION FOR ABOUT 24 HOURS, AND MAY
INDUCE SOME WEAKENING. AFTER TAU 96, THE SYSTEM ONCE AGAIN MOVES INTO
A LOWER SHEAR ENVIRONMENT AND WILL RESUME ITS INTENSIFICATION TREND
THROUGH THE END OF THE FORECAST PERIOD.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
GOOD AGREEMENT ON THE OVERALL TRACK SCENARIO OF A NORTHWESTWARD,
THEN WESTWARD, TRAJECTORY. CROSS-TRACK SPREAD INCREASES TO 230NM BY
TAU 72, BETWEEN THE EGRR ON THE NORTH SIDE OF THE ENVELOPE AND THE
GFS ON THE SOUTHERN EDGE. HOWEVER, THE EGRR LOSES THE VORTEX AFTER
TAU 72, AND IS SUCH A SIGNIFICANT OUTLIER, THAT IT HAS BEEN
DISCARDED FROM THE CONSENSUS. THE REMAINDER OF THE CONSENSUS
MEMBERS SHOW A MORE SUBDUED SPREAD OF 160NM AT TAU 72. BY TAU 120
THE CROSS-TRACK SPREAD INCREASES TO 400NM, WITH NAVGEM NOW TAKING
THE PLACE OF THE EGRR IN BEING A MARKED OUTLIER TO THE NORTH,
TAKING THE SYSTEM OVER OKINAWA. AGAIN, THIS IS UNREALISTIC, AND
NAVGEM IS KNOWN TO HAVE A POLEWARD BIAS AND THUS HAS BEEN DISCARDED
FROM THE CONSENSUS. THE REMAINDER OF THE GUIDANCE PACKAGE IS SPREAD
ACROSS A 220NM ENVELOPE AT TAU 120, WITH THE ECMWF ON THE NORTH
SIDE AND GFS ON THE SOUTH. ENSEMBLE GUIDANCE CONTINUES TO BE
CONSISTENT WITH THE TRACK SCENARIO AND THE JTWC FORECAST WITH
UNCERTAINTY DECREASING IN BOTH THE GEFS AND ECENS OVER THE PAST
COUPLE OF RUNS. THE JTWC FORECAST IS PLACED ON THE SOUTHERN SIDE OF
THE ENVELOPE AND IS CONSISTENT WITH THE GEFS AND EC-AIFS TRACKERS.
INTENSITY GUIDANCE REMAINS CONSISTENT WITH THE LAST COUPLE OF RUNS,
WITH THE MESOSCALE GUIDANCE FAR OUTPACING THE DECAY-SHIPS. HOWEVER,
THE PEAKS HAVE FOR THE MOST PART BACKED OFF A BIT WITH THIS RUN,
EXCEPT FOR THE COAMPS-TC (GFS) WHICH INSISTS THIS IS GOING TO BE A
SUPER-TYPHOON ONE DAY. THE HAFS-A PEAK HAS DROPPED TO 95 KNOTS. THE
JTWC FORECAST IS PLACED NEAR THE HAFS-A THROUGH TAU 96, THEN CLOSE
TO THE COAMPS-TC TRACKER THEREAFTER.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
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 2025-8-7 22:25
