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JTWC/16W/#23/08-12 12Z Prognostic Reasoning
WDPN32 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (PODUL) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 21.6N 125.0E
INITIAL INTENSITY: 80 KTS
GEOGRAPHIC REFERENCE: 285 NM SOUTHEAST OF TAIPEI, TAIWAN
MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
SIGNIFICANT WAVE HEIGHT: 34 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A
SIGNIFICANT IMPROVEMENT IN OVERALL STRUCTURE, WITH A LARGE,
ALTHOUGH STILL SOMEWHAT RAGGED, EYE DEVELOPING OVER THE PAST FEW
HOURS. BANDS OF RELATIVELY STRONG CONVECTION CONTINUE TO DEVELOP IN
A BAND ALONG THE SOUTHERN PERIPHERY OF THE CIRCULATION, AND BRIEFLY
WRAP UPSHEAR, BUT HAVE NOT BEEN ABLE TO ESTABLISH A FULLY CLOSED
EYEWALL ON THE NORTHEAST SIDE. THIS IS LIKELY DUE TO PERSISTENT
NORTHEASTERLY SHEAR, WHICH DUE TO A LACK OF CIMSS DATA IS BASED
SOLELY ON MODEL DERIVED DATA. LIKELY THERE IS ENHANCED MID-LEVEL
SHEAR FROM THE EAST-NORTHEAST, AS WELL AS SOME LINGERING DRY AIR,
BOTH OF WHICH ARE INHIBITING THE CONVECTION FROM FULLY PUSHING
UPSHEAR AND ESTABLISHING A SOLID EYEWALL. A 121238Z GMI 37GHZ IMAGE
REVEALS A BEAN-SHAPED MICROWAVE EYE, WITH A SOLID EYEWALL IN ALL
QUADRANTS SAVE FOR THE NORTH-NORTHEAST SECTOR. THE 89GHZ IMAGE
PRETTY MUCH TELLS THE SAME STORY, WITH THE DRYNESS IN THE
MID-LEVELS ESPECIALLY PREVALENT IN THE 89GHZ IMAGE. COMPARISON OF
THE TWO BANDS REVEALS A SMALL AMOUNT OF VORTEX TILT TO THE
WEST-SOUTHWEST. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE 37GHZ MICROWAVE IMAGE. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED SLIGHTLY
HIGHER THAN THE T4.5 DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW
AND KNES. OF NOTE, CIMSS DATA IS INTERMITTENT AND STRUGGLING TO
MAINTAIN A LOCK ON THE TARGET AND IS SIGNIFICANTLY UNDER-ESTIMATING
THE CURRENT INTENSITY, BUT RAW ADT VALUES WERE AS HIGH AS T5.4
EARLIER. ENVIRONMENTAL CONDITIONS ARE IN THE AGGREGATE FAVORABLE
WITH LOW TO MODERATE DEEP-LAYER SHEAR, WARM SSTS AND MODERATE
OUTFLOW ALOFT, OFFSET SOMEWHAT BY THE MORE NEGATIVE FACTORS
DISCUSSED ABOVE.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF AN EXTENSIVE
SUBTROPICAL RIDGE (STR) COMPLEX EXTENDING FROM SOUTHERN CHINA,
SOUTH OF HONSHU AND INTO THE NORTHERN PACIFIC.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.5 - 77 KTS
RJTD: T4.0 - 65 KTS
RCTP: T5.0 - 90 KTS
KNES: T4.5 - 77 KTS
CIMSS ADT: 57 KTS AT 121100Z
CIMSS AIDT: 67 KTS AT 121100Z
CIMSS D-PRINT: 67 KTS AT 121100Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 30-31 CELSIUS
OUTFLOW: MODERATE WESTWARD
OTHER FACTORS: WEAK EQUATORWARD OUTFLOW. RELATIVELY DRIER
MID-LEVEL AIR IN THE NORTHEASTERN QUADRANT.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: LOW
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 CONTINUE
TRACKING TOWARDS THE NORTHWEST ALONG THE SOUTHERN SIDE OF THE STR
TO THE NORTH, THROUGH THE FORECAST PERIOD. AS THE SYSTEM APPROACHES
TAIWAN, THE TRACK WILL VERY LIKELY EXHIBIT ERRATIC MOTION, WITH
RACK DEFLECTION, EITHER RIGHT OR LEFT OF THE OVERALL TRACK, AS WELL
AS SIGNIFICANT DECELERATION. THE AMOUNT OF TRACK DEFLECTION OR
DECELERATION WILL IN LARGE PART DEPEND ON THE EXACT LOCATION OF
LANDFALL ALONG THE CENTRAL MOUNTAIN RANGE (CMR) AND CANNOT AT THIS
TIME BE PREDICTED WITH ANY ACCURACY. ONCE THE SYSTEM DOES MAKE
LANDFALL, WITHIN THE NEXT 12 TO 18 HOURS, IT WILL EVENTUALLY PASS
OVER THE CMR, AND MOVE INTO THE TAIWAN STRAIT, BEFORE QUICKLY
CROSSING THE STRAIT AND MAKING A SECOND LANDFALL ALONG THE
SOUTHEASTERN COAST OF CHINA AROUND TAU 30, THEN CONTINUING INLAND
INTO SOUTHERN CHINA. IN TERMS OF INTENSITY, THE CONTINUED CYCLING
OF CONVECTION ALONG THE SOUTHERN AND SOUTHEASTERN PERIPHERY OF THE
VORTEX HAS HELPED PUSH BACK AGAINST THE SHEAR AND ANIMATED WATER
VAPOR IMAGERY CONFIRMS THAT THE UPPER-LEVEL FLOW IS SPLITTING
AROUND 250NM UPSTREAM OF THE CENTER. THE NEAREST UPPER-AIR SOUNDING
FROM ISHIGAKIJIMA SHOWS EASTERLY 200MB WINDS AT 55 KNOTS. COMBINED
WITH THE WATER VAPOR IMAGERY, EIR AND MICROWAVE IMAGERY, IT IS
ASSESSED THAT THE TIGHT SHEAR GRADIENT IS POSITIONED JUST NORTH OF
THE CORE OF TY 16W, WHILE THE CENTER AND THE SOUTHERN HALF IS UNDER
THE INFLUENCE OF SMALL-SCALE ANTICYCLONE ALOFT. GOING FORWARD,
MODEL FIELDS INDICATE CONTINUED MOISTENING OF THE CIRCULATION,
ALONG WITH FURTHER REDUCTION OF SHEAR, ALLOWING FOR ADDITIONAL
INTENSIFICATION THROUGH LANDFALL. ONCE THE SYSTEM MOVES ACROSS THE
CMR, IT WILL RAPIDLY WEAKEN, WITH THE VORTEX LIKELY DECOUPLING IN
THE PROCESS, BEFORE REFORMING IN THE TAIWAN STRAIT. HOWEVER, THE
SYSTEM IS NOT EXPECTED TO INTENSIFY IN THE STRAIT, AND IS FORECAST
TO MAKE LANDFALL AS A TROPICAL STORM, BEFORE RAPIDLY WEAKENING AND
DISSIPATING OVER SOUTHERN CHINA BY TAU 48.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE REMAINS
IN TIGHT AGREEMENT THROUGH THE FORECAST PERIOD, WITH JUST 35NM
CROSS-TRACK SPREAD AT LANDFALL, INCREASING TO 100NM BY THE END OF
THE FORECAST. THE JTWC FORECAST IS PLACED ON THE SOUTHERN EDGE OF
GUIDANCE ENVELOPE WITH HIGH CONFIDENCE. WHILE THE MODELS ARE IN
TIGHT AGREEMENT, THE ANTICIPATED ERRATIC TRACK MOTION PRIOR TO
LANDFALL MAY SIGNIFICANTLY ALTER BOTH THE TIMING AND LOCATION OF
LANDFALL AND THE SUBSEQUENT TRACK. INTENSITY GUIDANCE IS ALSO IN
TIGHT AGREEMENT AND CONSISTENT WITH THE PREVIOUS GUIDANCE PACKAGE.
THE INTERPOLATED HAFS-A AND HWRF CONTINUE TO BE THE MOST
AGGRESSIVE, PEAKING THE SYSTEM AT BETWEEN 85 AND 95 KNOTS
RESPECTIVELY. MEANWHILE THE NON-INTERPOLATED 06Z RUNS OF BOTH
MODELS ARE EVEN MORE AGGRESSIVE, WITH PEAKS AS HIGH AS 115 KNOTS.
THE JTWC FORECAST IS PLACED ON THE HIGH EDGE OF THE GUIDANCE,
CONSISTENT WITH THE INTERPOLATED HWRF, THEN WEAKENS THE SYSTEM AT A
SLIGHTLY FASTER RATE THAN THE BULK OF THE GUIDANCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: MEDIUM//
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楼主: ygsj24
发表于 2025-8-12 20:38
