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JTWC/25W/#38/09-27 18Z Prognostic Reasoning
WDPN33 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 038//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 33.2N 160.5E
INITIAL INTENSITY: 75 KTS
GEOGRAPHIC REFERENCE: 896 NM NORTH-NORTHWEST OF WAKE ISLAND
MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 17 KTS
SIGNIFICANT WAVE HEIGHT: 36 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
DRAMATICALLY IMPROVED STRUCTURE, WITH THE RECENT EMERGENCE OF A
20NM WIDE EYE FEATURE. CLOUD TOP TEMPS (CTT) ARE COLD FOR THIS
LATITUDE, BUT NOT EXCESSIVELY SO, WITH THE MINIMUM CTT AROUND -80C
IN THE SOUTHEASTERN QUADRANT. A LACK OF RECENT MICROWAVE IMAGERY
PRECLUDES A FULL ANALYSIS, BUT EIR IMAGERY SUGGESTS THE EYEWALL IS
OPEN ON THE NORTHWEST SIDE. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE 20NM EYE IN THE EIR, AND A TIGHT
GROUPING OF AGENCY FIX POSITIONS. THE INITIAL INTENSITY IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE HIGHER-END AGENCY
FIXES (T5.0) AND THE LOWER OBJECTIVE ESTIMATES WHICH RANGE FROM
60-74 KNOTS. THE ENVIRONMENT REMAINS FAVORABLE, WITH WARM SSTS, AND
LOW VWS. CIMSS ATMOSPHERIC MOTION VECTOR (AMV) WINDS AND ANIMATED
WATER VAPOR IMAGERY SHOW EXTREMELY STRONG POLEWARD OUTFLOW,
EXCEEDING 75 KNOTS, INTO THE ENTRANCE REGION OF A JET MAX NORTH OF
45N.
INITIAL WIND RADII BASIS: SCATTEROMETER DATA
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.5 - 77 KTS
RJTD: T5.0 - 90 KTS
RCTP: T5.0 - 90 KTS
KNES: T5.0 - 90 KTS
CIMSS SATCON: 65 KTS AT 271533Z
CIMSS ADT: 67 KTS AT 271730Z
CIMSS AIDT: 63 KTS AT 271730Z
CIMSS D-MINT: 60 KTS AT 271533Z
CIMSS D-PRINT: 74 KTS AT 271730Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 26-27 CELSIUS
OUTFLOW: STRONG POLEWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TYPHOON (TY) 25W IS APPROACHING THE AXIS OF
THE STR TO THE EAST, AND HAS SLOWED SLIGHTLY OVER THE LAST 12 TO 24
HOURS AS IT REACHES THE RIDGE AXIS. ONCE PASSING THE AXIS WITHIN
THE NEXT 12 HOURS, TY 25W WILL ACCELERATE NORTHEASTWARD THROUGH TAU
24, BEFORE SLOWING ONCE MORE AS IT MOVES TO THE NORTH OF THE RIDGE
AND INTO A WEAKER STEERING ENVIRONMENT. THE SYSTEM HAS TAKEN
ADVANTAGE OF THE STRONG, DIVERGENT, POLEWARD OUTFLOW OVER THE PAST
24 HOURS AND HAS QUICKLY REINTENSIFIED UNDER THESE VERY FAVORABLE
CONDITIONS. GLOBAL MODELS SUGGEST POLEWARD DIVERGENCE WILL CONTINUE
TO STRENGTHEN OVER THE NEXT 12 TO 24 HOURS, WHILE SHEAR REMAINS
RELATIVELY LOW, AS THE SYSTEM MOVES CLOSER TO THE ENTRANCE REGION
OF THE JET MAX TO THE NORTH. BY TAU 18 HOWEVER, SHEAR IS FORECAST
TO INCREASE SHARPLY AND WILL RAPIDLY COME TO OFFSET THE POSITIVE
EFFECT OF THE ROBUST OUTFLOW. BY TAU 24, THE SYSTEM WILL START TO
SHEAR APART WHILE SIMULTANEOUSLY BEGINNING EXTRATROPICAL TRANSITION
(ETT). BY TAU 36, THE VORTEX WILL BE TORN ASUNDER, BE SMOTHERED IN
DRY AIR, AND THE SYSTEM WILL UNDERGO RAPID FRONTOGENESIS, MARKING
THE COMPLETION OF ETT AS A STORM-FORCE LOW.
MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT, WITH MINIMAL CROSS- OR ALONG-TRACK SPREAD THROUGH THE
FORECAST PERIOD. THE JTWC FORECAST IS PLACED NEAR THE CONSENSUS
MEAN THROUGH THE ENTIRE FORECAST WITH HIGH CONFIDENCE. INTENSITY
GUIDANCE IS MORE MIXED, WITH THE SHIPS (BOTH GFS AND NAVGEM)
INDICATING NO ADDITIONAL INTENSIFICATION THROUGH TAU 12, FOLLOWED
BY RAPID WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD.
MEANWHILE, THE COAMPS-TC AND HAFS-A BOTH DEPICT THE SYSTEM RAPIDLY
INTENSIFYING UP TO 95 KNOTS BY TAU 12 BEFORE WEAKENING EQUALLY
RAPIDLY THEREAFTER. ADDITIONALLY, THE RIDE RAPID INTENSIFICATION
AID IS TRIPPED, ALSO INDICATING A PEAK INTENSITY OF 95 KNOTS AT TAU
12. THE JTWC FORECAST IS POSITIONED CLOSER TO THE CONSENSUS MEAN,
WHICH PEAKS AT 85 KNOTS, BEFORE RAPIDLY WEAKENING IMMEDIATELY
THEREAFTER.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: MEDIUM//
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