WDPN31 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEKKHALA) WARNING NR 
032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.5N 129.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 668 NM SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 07W (MEKKHALA) AS A FULLY EXPOSED AND ELONGATED
LOW-LEVEL CIRCULATION CENTER (LLCC). THE SYSTEM MADE LANDFALL IN
AMAMI OSHIMA AT 261200Z; THE SURFACE OBSERVATION RECORDED ON AMAMI
OSHIMA AT THAT TIME WAS 24 KTS, WHICH WAS ALSO THE MAXIMUM
WIND SPEED THE SITE REPORTED AS 07W APPROACHED IT. THE 261142Z ASCAT
PASS CONFIRMS THE ELONGATED CENTER AND REVEALS A HIGHLY ASYMMETRIC
WIND FIELD, WITH THE MAXIMUM WINDS CONFINED TO THE SOUTHEASTERN
QUADRANT AND DISPLACED APPROXIMATELY 75 NM FROM THE CENTER.
ENVIRONMENTAL ANALYSIS REVEALS AN INHOSPITABLE ENVIRONMENT,
CHARACTERIZED BY HIGH (20-25 KTS) VERTICAL WINDS SHEAR (VWS), POOR
OUTFLOW, AND A RELATIVELY DRIER ENVIRONMENT THAT IS BEGINNING TO
ENTRAIN INTO THE CORE FROM THE WEST. THE SEA SURFACE TEMPERATURES
ARE STILL FAVORABLE (26-27 C), BUT DO LITTLE TO IMPROVE THE
CONDITIONS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE FULLY EXPOSED LLCC IN ANIMATED EIR AND THE 261142Z
ASCAT PASS. THE INITIAL INTENSITY OF 35 KTS IS ALSO ASSESSED WITH
HIGH CONFIDENCE BASED ON THE 261142Z ASCAT PASS.

INITIAL WIND RADII BASIS: ADJUSTED WIND RADII USING THE 261142Z
METOP-B ASCAT DATA

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS ADT: 25 KTS AT 261340Z
   CIMSS AIDT: 32 KTS AT 261340Z
   CIMSS D-MINT: 31 KTS AT 261009Z
   CIMSS D-PRINT: 29 KTS AT 261340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 07W IS FORECAST TO CONTINUE TRACKING
GENERALLY NORTHEASTWARD FOR THE DURATION OF THE FORECAST PERIOD AS
IT IS STEERED BY THE STR TO ITS EAST. MEKKHALA IS CURRENTLY
UNDERGOING EXTRATROPICAL TRANSITION (ETT), AS IT IS FULLY EMBEDDED
IN THE UPPER-LEVEL WESTERLIES, DISPLAYS AN ELONGATED LOW-LEVEL WITH
AN ASYMMETRIC WIND FIELD, AND HAS BEGUN TO DEMONSTRATE TEMPERATURE
ADVECTION. ETT IS ANTICIPATED TO BE COMPLETE NO LATER THAN TAU 24, BUT 
LIKELY WELL BEFORE. REGARDING INTENSITY, MEKKHALA IS FORECAST TO 
MAINTAIN ITS INTENSITY THROUGH TAU 24 WHILE IT COMPLETES ETT AND 
WEAKEN SLIGHTLY BY TAU 36; HOWEVER, THE POSSIBILITY FOR EARLIER 
WEAKENING IS POSSIBLE AS THE SYSTEM TRACKS DEEPER INTO THE HOSTILE 
ENVIRONMENT.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGH TAU 12, WITH NEGLIGIBLE DIFFERENCES BETWEEN 
MEMBERS. AS A RESULT, THE JTWC TRACK FORECAST IS LAID WITH HIGH
CONFIDENCE. THE JTWC INTENSITY FORECAST DEVIATES SLIGHTLY FROM
INTENSITY AIDS, WHICH STILL DEPICT 07W QUICKLY INTENSIFYING FOR 12
HOURS BEFORE DRAMATICALLY WEAKENING. GIVEN THE INCREASINGLY HOSTILE
ENVIRONMENT, THIS OUTCOME WAS DEEMED UNLIKELY, THOUGH THE
POSSIBILITY CANNOT BE ENTIRELY RULED OUT. THE JTWC INTENSITY
FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE.

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