WDPN32 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (LEEPI)  
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.9N 146.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 452 NM SOUTH-SOUTHEAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN 
IMPROVED RADIAL OUTFLOW AND MORE CONSOLIDATED APPEARANCE TO TD 13W 
(LEEPI). IN ADDITION TO THE SYSTEM'S PRODUCTION OF WEAK RADIAL 
OUTFLOW, A MODERATE EQUATORWARD OUTFLOW CHANNEL WITH TRANSVERSE 
BANDING IS ALSO PRESENT, BUT TO A LESSER EXTENT THAN PREVIOUSLY 
OBSERVED. THE LLCC REMAINS PARTIALLY EXPOSED AS SHEAR BUFFETS THE 
NORTHERN SIDE. THE CONVECTION CONSISTS OF A QUASI-CIRCULAR PLUME WITH 
NO APPARENT CURVATURE OR WRAPPING, WHICH IS WHY THE SYSTEM HAS BEEN 
DEEMED STATUS QUO IN TERMS OF THE INTENSITY. A 051153Z ASCAT PARTIAL 
PASS SHOWS A PATCH OF 25 KTS ON THE SOUTH SIDE OF THE LLCC, JUST WEST 
OF THE PRIMARY AREA OF CONVECTION. OBJECTIVE INTENSITY ESTIMATES FROM
CIMSS RANGE BETWEEN 30-40 KTS. WITHOUT A MORE COMPLETE VIEW OF THE
WIND DATA TO SUPPORT SUCH AN UPGRADE, THE INTENSITY IS ASSESSED
WITH MEDIUM CONFIDENCE. DUE TO THE PARTIAL EXPOSURE OF THE LLCC
WITH LOW CLOUD LINES WRAPPING INTO THE CIRCULATION ON THE NW SIDE
APPARENT ON ANIMATED EIR IMAGERY, THE POSITION IS ASSESSED WITH
HIGH CONFIDENCE.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: DEEP LAYER STR TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 35 KTS AT 050830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: DESPITE SHOWING A BURST OF IMPROVED CONVECTION
AND RADIAL OUTFLOW, THE MOMENTARY GAINS OF TD 13W WILL BE
SHORT-LIVED. BETWEEN TAU 0 AND TAU 12, A FLUCTUATION TO NEAR 35 KTS
COULD OCCUR IN AREAS OF CONVECTION. OVERALL, THE SYSTEM IS EXPECTED
TO MAINTAIN A STEADY INTENSITY AS IT PICKS UP SPEED IN A
NORTHEASTWARD TRACK. A TUTT CELL OVERHEAD IS CONTRIBUTING TO THE
WOES OF TD 13W, CREATING WEAK CONVERGENCE ALOFT AND INHIBITING
FURTHER DEVELOPMENT. WARM SSTS (27-28C) WILL CONTINUE EVEN IN MORE
POLEWARD LATITUDES THROUGHOUT THE FORECAST PERIOD, BUT IT WILL
OFFER LITTLE CONSOLATION AS THE SYSTEM APPROACHES INCREASING
BAROCLINICITY AND HEIGHTENED VWS VALUES (30-37 KTS). A STRONG
STEERING INFLUENCE FROM THE DEEP STR TO THE EAST HAS RESULTED IN A
VERY CONSISTENT AND HIGH CONFIDENCE TRACK, WHICH CAN BE SUMMARIZED
AS A NORTHEASTWARD ACCELERATION THROUGH TAU 36. AS TD 13W ENTERS
THE MID-LATITUDE WESTERLIES, EXTRATROPICAL TRANSITION WILL OCCUR IN 
THE PERIOD BETWEEN TAU 24 AND TAU 36.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE HAS REMAINED IN VERY
TIGHT AGREEMENT FOR THE TRACK OF TD 13W, WITH LITTLE VARIATION
BETWEEN MODEL RUNS. NEGLIGIBLE DIFFERENCES BETWEEN MODEL GUIDANCE
IS ONLY IN HOW QUICKLY TD 13W WILL TRACK NORTHEASTWARD. THE JTWC
TRACK FORECAST ALIGNS MOST CLOSELY WITH THE CONSENSUS MEAN AND IS
FORECAST TO BE ON THE HIGHER END OF CONSENSUS MEAN TRACK SPEEDS.
THE INTENSITY GUIDANCE HAS A WIDER SPREAD ACROSS THE CONSENSUS,
WITH THE BULK OF THE GUIDANCE SHOWING A GRADUAL DECLINE. THE JTWC
FORECAST MAINTAINS INTENSITY BUT REMAINS WELL WITHIN THE CONSENSUS.
CONFIDENCE IS HIGH FOR BOTH THE JTWC TRACK AND INTENSITY FORECASTS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH//
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