WDPN31 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEKKHALA) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.6N 125.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 279 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 07W (MEKKHALA) IS DEPICTED ON ANIMATED ENHANCED
INFRARED (EIR) IMAGERY WITH A LOW LEVEL CIRCULATION CENTER (LLCC)
THAT IS BECOMING INCREASINGLY DECOUPLED FROM THE DISORGANIZED
CONVECTIVE BURSTS CENTERED ON THE SOUTHERN SEMICIRCLE OF THE
SYSTEM. ENVIRONMENTAL ANALYSIS REVEALS UNFAVORABLE CONDITIONS
OFFSET ONLY BY WARM (28-29 C) SEA SURFACE TEMPERATURES (SSTS) AND
MODERATE EQUATORWARD OUTFLOW ALOFT, WHILE HIGH (30-35 KTS) OF
VERTICAL WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT FROM THE NORTH
CONTRIBUTE TO THE ASYMMETRICAL APPEARANCE OF TS 07W IN SATELLITE
IMAGERY. THE INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE PARTIALLY OBSCURED LLCC BEGINNING TO EMERGE ON
ANIMATED EIR IMAGERY. THE INITIAL INTENSITY IS ALSO ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS
OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: ADJUSTED WIND RADII BASED ON 240937Z SAR
IMAGE.

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 60 KTS AT 241800Z
   CIMSS ADT: 53 KTS AT 241800Z
   CIMSS AIDT: 59 KTS AT 241800Z
   CIMSS D-MINT: 39 KTS AT 241710Z
   CIMSS D-PRINT: 45 KTS AT 241730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30-35 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS 07W HAS AT LAST BEGUN ITS
NORTH-NORTHEASTWARD TURN AS IT ROUNDS THE AXIS OF THE WESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AS
IT DOES SO, IT IS FORECAST TO INCREASE TRACK SPEED AS IT TRANSITS
ROUGHLY 30 NM TO THE WEST OF OKINAWA SHORTLY AFTER TAU 36, AND
ONWARDS TO PARALLEL THE SOUTHERN COASTS OF KYUSHU AND HONSHU
THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD. IN TERMS OF
INTENSITY, TS 07W IS EXPECTED TO STEADILY DECREASE IN INTENSITY AS
IT PROCEEDS INTO AN INCREASINGLY HOSTILE ENVIRONMENT OF HIGH VWS,
DRY AIR, AND COOLING SSTS. HOWEVER, TS 07W IS FORECAST TO MAINTAIN
TROPICAL STORM LEVEL INTENSITY THROUGHOUT THE REMAINDER OF THE
FORECAST PERIOD. EXTRATROPICAL TRANSITION (ETT) IS FORECAST TO
BEGIN BY TAU 48 AS TS MEKKHALA NEARS STRONGER UPPER-LEVEL
WESTERLIES, EVENTUALLY EMBEDDING UNDERNEATH THE JET STREAM, AND BY
TAU 72 TS 07W IS FORECAST TO BE FULLY EXTRATROPICAL.

MODEL DISCUSSION: MODEL TRACK FORECAST GUIDANCE IS IN GOOD
AGREEMENT WITH THE EXCEPTION OF GALWEM AND ECMWF DETERMINISTIC AND
ENSEMBLES, WHICH ALL FORECAST A MUCH FASTER TRACK SPEED AND ARE
OUTLIERS TO THE NORTH. AN ADJUSTED MULTI-MODEL CONSENSUS WAS USED
INSTEAD TO EXCLUDE THESE OUTLIERS, AND THE OFFICIAL JTWC FORECAST
IS THUS LAID WITH HIGH CONFIDENCE, IN BETWEEN THE EXPERIMENTAL AI
CONSENSUS TRACK AND ADJUSTED MULTI-MODEL CONSENSUS TRACK. INTENSITY
MODEL GUIDANCE REMAINS SPREAD 15-20 KTS THROUGHOUT THE REMAINDER OF
THE FORECAST PERIOD SO THE OFFICIAL JTWC INTENSITY FORECAST IS
ASSESSED WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM//
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