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发表于 2025-8-12 16:34
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JTWC/16W/#22/08-12 06Z Prognostic Reasoning
WDPN32 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (PODUL) WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 21.3N 126.5E
INITIAL INTENSITY: 70 KTS
GEOGRAPHIC REFERENCE: 320 NM SOUTH-SOUTHWEST OF KADENA AB
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 16 KTS
SIGNIFICANT WAVE HEIGHT: 29 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY
CONSOLIDATING AND COMPACT SYSTEM. MODERATE CONVECTION WAS SEEN
DEVELOPING ON THE SOUTHWESTERN SIDE OF THE LOW LEVEL CIRCULATION
CENTER (LLCC) AND PUSHING UPSHEAR TO THE EASTERN SIDE OF THE CENTER,
JUST PRIOR TO AND CONTINUING THROUGH THE 0600Z HOUR. THIS CONVECTION
SUBSEQUENTLY WARMED AND DISSIPATED, BUT ANOTHER CONVECTIVE DEVELOPMENT
CYCLE IS CURRENTLY UNDERWAY. WITH EACH SUCCESSIVE
CYCLE, ANIMATED WATER VAPOR IMAGERY SHOWS GRAVITY WAVES PUSHING
UPSHEAR, TO THE EAST, WHICH IN TURN IS PUSHING THE SHEAR FRONT BACK TO
THE EAST. THIS HAS RESULTED IN A SPLIT IN THE UPPER-LEVEL FLOW ABOUT
200NM UPSTREAM OF THE LLCC, LEADING TO AN OVERALL REDUCTION IN
OUTFLOW-LEVEL SHEAR. THE LATEST FRAMES OF MSI AND EIR SHOW THE
DEVELOPMENT OF A WARM SPOT, SUGGESTING THAT AN EYE MAY SOON APPEAR.
A 120512Z AMSR2 PASS REVEALED A LOW-LEVEL MICROWAVE EYE FEATURE IN
THE 37GHZ BAND, WHILE THE 89GHZ BAND REVEALED A SLIGHTLY TILTED
VORTEX BUT NO MICROWAVE EYE FEATURE. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A SHORT EXTRAPOLATION OF THE
MICROWAVE EYE IN THE AMSR2 IMAGE DISCUSSED ABOVE. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED SLIGHTLY
HIGHER THAN THE AGENCY SUBJECTIVE DVORAK CURRENT INTENSITY
ESTIMATES, BASED ON THE RAPIDLY IMPROVING STRUCTURE. ENVIRONMENTAL
CONDITIONS ARE FAVORABLE, WITH WARM SSTS, LOW EASTERLY SHEAR AND
MODERATE WESTWARD OUTFLOW ALOFT.
INITIAL WIND RADII BASIS: PERSISTENCE WITH EARLIER SAR DATA.
CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF AN EXTENSIVE
DEEP-LAYER SUBTROPICAL RIDGE (STR) EXTENDING FROM SOUTHERN CHINA TO
SOUTH OF THE ALEUTIAN ISLANDS.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T4.0 - 65 KTS
RCTP: T4.0 - 65 KTS
KNES: T4.0 - 65 KTS
CIMSS SATCON: 60 KTS AT 120600Z
CIMSS ADT: 55 KTS AT 120600Z
CIMSS AIDT: 47 KTS AT 120600Z
CIMSS D-PRINT: 60 KTS AT 120600Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE WESTWARD
OTHER FACTORS: WEAK EQUATORWARD OUTFLOW.
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: TYPHOON (TY) 16W IS FORECAST TO TRACK
WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF AN EXTENSIVE STR
THROUGH THE FORECAST PERIOD. AS THE SYSTEM APPROACHES THE SOUTHEAST
COAST OF TAIWAN, THE POTENTIAL FOR ERRATIC MOTION WILL INCREASE, TO
INCLUDE RAPID DECELERATION AND TRACK DEFLECTIONS, EITHER RIGHT OR
LEFT, DUE TO OROGRAPHIC FORCING. THE 12-HOUR TIME STEPS OF THE
FORECAST ARE NOT SUFFICIENT TO CAPTURE THESE ERRATIC MOTIONS, AND
THUS, THE TRACK CONTINUES STRAIGHT OVER THE SOUTHERN PORTION OF TAIWAN
BETWEEN ROUGHLY TAU 18 AND TAU 30. SIGNIFICANT CHANGES TO THE
TIMING AND LOCATION OF LANDFALL ARE TO BE EXPECTED. AFTER CROSSING
TAIWAN, THE SYSTEM WILL CONTINUE TO TRACK WEST-NORTHWESTWARD,
MAKING A SECOND LANDFALL ALONG THE SOUTH-CENTRAL CHINESE COASTLINE,
BEFORE CONTINUING INLAND THROUGH THE REMAINDER OF THE FORECAST
PERIOD. IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS HAVE
IMPROVED SIGNIFICANTLY, PARTICULARLY IN REFERENCE TO THE DEEP-LAYER
SHEAR. GLOBAL AND MESOSCALE MODELS SUGGEST THIS TREND WILL
CONTINUE, WITH LOW TO MODERATE (10-20 KTS) OF EASTERLY SHEAR
EXPECTED TO PERSIST THROUGH THE NEXT 24 HOURS. HOWEVER, AS
DISCUSSED ABOVE, THE UPPER-LEVEL FLOW HAS SPLIT UPSTREAM OF TY 16W,
LEADING TO EVEN LOWER SHEAR IN VICINITY OF THE SYSTEM. COUPLED WITH
INCREASING DEEP MOISTURE AND THE FACT THAT THE SYSTEM WILL BE
MOVING OVER A WEDGE OF SLIGHTLY WARMER (30-31C) WATERS AS IT
APPROACHES TAIWAN, TY 16W IS VERY LIKELY TO INTENSIFY SIGNIFICANTLY
PRIOR TO LANDFALL IN TAIWAN. THE FORECAST CALLS FOR A PEAK OF 85
KNOTS BY TAU 12. HOWEVER, THE ACTUAL PEAK COULD BE ABOUT 10-15
KNOTS HIGHER (95-100 KTS), OCCURRING BETWEEN TAU 12 AND LANDFALL,
AS SHOWN ACROSS MULTIPLE MESOSCALE MODELS. AFTER LANDFALL, THE
SYSTEM WILL RAPIDLY WEAKEN OVER THE RUGGED TERRAIN OF THE CENTRAL
MOUNTAIN RANGE, LIKELY EMERGING INTO THE TAIWAN STRAIT AS A STRONG
TROPICAL STORM. THE SYSTEM IS UNLIKELY TO REINTENSIFY OVER THE
STRAIT, AND MAKE ITS SECOND LANDFALL AS A TROPICAL STORM, BEFORE
RAPIDLY WEAKENING AND DISSIPATING OVER SOUTHERN CHINA BY THE END OF
THE FORECAST PERIOD.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
STRONG AGREEMENT, WITH MINIMAL CROSS- OR ALONG-TRACK SPREAD
THROUGHOUT THE FORECAST PERIOD. THE JTWC FORECAST IS POSITIONED ON
THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE, CLOSE TO THE GFS, GEFS
MEAN, AND ECMWF-AIFS TRACKERS. INTENSITY GUIDANCE HAS DECREASED
SLIGHTLY FROM THE PREVIOUS RUN, SPECIFICALLY THE RAPID
INTENSIFICATION (RI) AIDS SEEN WITH THE 00Z RUN HAVE DISAPPEARED
WITH THE 06Z RUN. THE INTERPOLATED HAFS-A, HWRF AND COAMPS-TC
GUIDANCE PEAK AROUND 80 KNOTS AT TAU 12, HOWEVER THE NON-INTERPOLATED
MEMBERS PEAK BETWEEN 95-100 KNOTS, WHICH SEEMS VERY REASONABLE BASED
ON THE CURRENT TRENDS AND EXPECTED CONDITIONS. THE PREVIOUS RUNS RI
GUIDANCE ALSO PEAKED IN THIS RANGE, AND THE MOST RECENT COAMPS-TC
ENSEMBLE INTENSITY PROBABILITY PRODUCT INDICATES AN APPROXIMATELY 40
PERCENT CHANCE OF RI PRIOR TO LANDFALL AND A SIMILAR PROBABILITY OF A
STRONG TYPHOON (100-129 KTS) MAKING LANDFALL IN TAIWAN.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: MEDIUM//
NNNN
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楼主: ygsj24
发表于 2025-8-12 17:22
