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发表于 2025-10-18 17:02
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JTWC/30W/#02/10-18 06Z Prognostic Reasoning
WDPN31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 30W (FENGSHEN)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 13.0N 124.7E
INITIAL INTENSITY: 30 KTS
GEOGRAPHIC REFERENCE: 236 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 15 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A HIGHLY
COMPLEX SITUATION, WITH AN EXTREMELY TILTED AND DISORGANIZED VORTEX
AND POTENTIALLY MULTIPLE VORTICES. EARLIER ASCAT DATA AT 180105Z
INDICATED A CLEAR-CUT LOW LEVEL CIRCULATION CENTER LOCATED JUST OFF
THE COAST OF NORTHEAST SAMAR, WHILE ANIMATED MSI AT THAT TIME
SHOWED SIGNIFICANT DEEP CONVECTION FURTHER TO THE SOUTHEAST AND
SOME POSSIBLE TURNING IN THE CLEAR AIR TO THE NORTH. A MORE RECENT
180407Z OSCAT-3 PASS SHOWS A WEAK LLCC JUST NORTH OF BANTAYAN BAY
ON THE NORTH COAST OF SAMAR 20-30 KNOT WINDS WRAPPING INTO THE
CIRCULATION AND HIGHER WINDS TO THE EAST OF SAMAR. A 180408Z GMI
89GHZ MICROWAVE IMAGE MEANWHILE SHOWS A CLEAR-CUT MID-LEVEL
CIRCULATION WELL EAST OF SAMAR AND ONLY A VERY WEAK REPRESENTATION
OF A LLCC NORTH OF SAMAR. THE MSI LOOP CLEARLY SHOWS SOUTHEASTERLY
WINDS TO THE NORTHEAST OF SAMAR, AND FLEETING HINTS OF A POSSIBLE
CIRCULATION BETWEEN NORTHERN SAMAR AND CATANDUANES AND SOUTHEASTERN
LUZON. SURFACE OBSERVATIONS FROM CATARMAN AND VIRAC HAVE ASSISTED
IN NARROWING DOWN THE INITIAL POSITION, WHICH IS PLACED WITH LOW
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE, RELIANT UPON THE SCATTEROMETER DATA INDICATING WINDS
ASSOCIATED WITH THE LLCC REMAIN LESS THAN 35 KNOTS, AND IN
ALIGNMENT WITH THE BULK OF THE SUBJECTIVE AND OBJECTIVE INTENSITY
ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS ARE FAVORABLE, WITH
VERY WARM SSTS, VERY HIGH OHC, LOW VWS AND GOOD RADIAL OUTFLOW.
PROXIMITY TO LAND AND THE HIGHLY TILTED NATURE OF THE VORTEX
HOWEVER, ARE CURRENTLY PLACING A SIGNIFICANT HINDRANCE ON
DEVELOPMENT.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T3.0 - 45 KTS
RCTP: T2.0 - 30 KTS
KNES: T3.0 - 45 KTS
CIMSS ADT: 33 KTS AT 180530Z
CIMSS AIDT: 32 KTS AT 180530Z
CIMSS D-MINT: 29 KTS AT 180453Z
CIMSS D-PRINT: 32 KTS AT 180640Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE RADIAL
OTHER FACTORS: LARGE AMOUNT OF VORTEX TILT AND DISORGANIZATION.
ANALYSIS CONFIDENCE:
INITIAL POSITION: LOW
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: IN THE NEAR-TERM (OVER THE NEXT 12 HOURS), THE
TRACK OF TD 30W IS LIKELY TO BE HIGHLY ERRATIC, DUE TO THE FACT
THAT THERE MAY BE MULTIPLE VORTICES, THE INFLUENCE OF THE LOCALIZED
TERRAIN ON THE LLCC MOTION, AND THAT THE VORTEX EXHIBITS
SIGNIFICANT TILT AND MISALIGNMENT. OVERALL, OVER THE NEXT 12 HOURS
THE SYSTEM IS EXPECTED TO TRACK NORTHWESTWARD, ROUGHLY PARALLEL THE
EASTERN COAST OF SOUTHERN LUZON. TRACK SPEEDS ARE FORECAST TO
INCREASE OVER THE NEXT 12 HOURS AS THE STEERING GRADIENT TIGHTENS.
TD 30W IS EXPECTED TO PASS NEAR POLILLO ISLAND AND THEN MAKE
LANDFALL ALONG THE EASTERN COAST OF LUZON AROUND TAU 18, THEN
RAPIDLY CROSS LUZON AND REFORM OFF THE WESTERN COAST OF LUZON
SHORTLY AFTER TAU 24. THE SYSTEM WILL CONTINUE TRACKING
NORTHWESTWARD UNTIL ABOUT TAU 48, WHEN THE OUTER EDGES OF THE
CIRCULATION WILL BEGIN TO INTERACT AND RUN INTO THE STRONG
NORTHEASTERLY COLD-SURGE FUNNELING SOUTHWARD OUT OF THE TAIWAN
STRAIT. BETWEEN TAU 48 AND TAU 72, TRACK SPEEDS SLOW TO FIVE KNOTS
OR LESS AS THE SYSTEM BOTH RUNS INTO THE COLD SURGE AND BECOMES
PARKED IN A WEAK STEERING PATTERN ALOFT. IN TERMS OF INTENSITY
THROUGH TAU 72, IN THE NEXT 12 HOURS OR SO, THE SYSTEM IS UNLIKELY
TO INTENSITY MUCH, ESPECIALLY DUE TO ITS PROXIMITY TO LAND AND THE
DISORGANIZED NATURE OF THE VORTEX. HOWEVER, ONCE IT MOVES OUT INTO
THE OPEN WATERS NEAR THE POLILLO ISLANDS, IT IS EXPECTED TO RAPIDLY
INTENSIFY TO AT LEAST 45 KNOTS, IN THE BRIEF PERIOD OF TIME PRIOR
TO MAKING LANDFALL. THE SYSTEM WILL WEAKEN SIGNIFICANTLY AS IT
CROSSES OVER THE RUGGED TERRAIN OF NORTHERN LUZON BUT QUICKLY
REINTENSIFY AFTER MOVING INTO THE SOUTH CHINA SEA. TD 30W WILL THEN
RAPIDLY INTENSITY ONCE MORE, REACHING A PEAK OF 70 KNOTS BY TAU 72
AS IT TAKES ADVANTAGE OF DRAMATICALLY IMPROVED OUTFLOW CONDITIONS.
AFTER TAU 72, THE SYSTEM WILL FACE A RAPID INFLUX OF DRY AIR AS IT
CONTINUES TO INTERACT WITH THE COLD SURGE, AND SHARPLY INCREASED
SHEAR, LEADING TO A FAIRLY RAPID WEAKENING PHASE, WHICH WILL
CONTINUE THROUGH THE REMAINDER OF THE FORECAST. DURING THIS TIME IN
THE FORECAST, THE DEEP-LAYER STEERING PATTERN REMAINS VERY WEAK.
HOWEVER, AS THE SYSTEM QUICKLY WEAKENS, IT WILL COME UNDER THE
STEERING INFLUENCE OF THE LOW- TO MID-LEVEL FLOW, WHICH WILL BE
FROM THE NORTHEAST. THIS WILL PUSH THE STEADILY WEAKENING TD 30W
SOUTHWESTWARD AFTER TAU 72.
MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN FAIRLY GOOD
AGREEMENT THROUGH TAU 72, WITH ALL MEMBERS OF THE CONSENSUS PACKAGE
INDICATING A NORTHWESTWARD TRACK, SLOWING AFTER TAU 48 AND REACHING
AN INFLECTION POINT NEAR TAU 72. CROSS-TRACK SPREAD AT TAU 72 IS
95NM BETWEEN THE ECMWF ON THE NORTHERN EDGE AND THE EGRR ON THE
SOUTH. ALONG-TRACK SPREAD IS MINIMAL TO TAU 48 BUT THEN BEGINS TO
INCREASE, UP TO 100NM BY TAU 72. AT THIS POINT THE MODELS BEGIN TO
SHOW SHARP DISAGREEMENTS, BOTH IN THE DIRECTION OF THE TRACK AND
HOW FAST THE SYSTEM WILL MOVE. THE NAVGEM TAKES THE SYSTEM SLOWLY
WESTWARD, REACHING THE EASTERN COAST OF HAINAN BY TAU 120, WHILE
THE GFS IS ONE OF THE SLOWEST MODELS, ONLY REACHING A POSITION
SOUTHEAST OF HAINAN BY TAU 120. THE ECMWF, EC-AIFS, AND GOOGLE DEEP
MIND ARE FASTER, BUT ONLY REACHING A MIDPOINT BETWEEN THE GFS AND
THE GEFS MEAN WHICH MAKES LANDFALL ALONG THE VIETNAMESE COAST BY
TAU 120. THE RESULT IS A CROSS-TRACK ENVELOPE OF 265NM AND AN
ALONG-TRACK SPREAD OF 230NM BY THE END OF THE FORECAST PERIOD. THE
JTWC FORECAST IS POSITIONED NEAR THE CONSENSUS MEAN THROUGH THE
FORECAST PERIOD. INTENSITY GUIDANCE IS IN GOOD AGREEMENT, AND THE
JTWC FORECAST IS POSITIONED CLOSE TO THE SHIPS TO TAU 36, THEN THE
HAFS-A THEREAFTER.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
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楼主: ygsj24
发表于 2025-10-18 20:38
