WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX)          
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.0N 141.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 625 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AFTER A BRIEF PERIOD OF CONSOLIDATION, ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS RAPID WEAKENING OF THE CORE CONVECTION 
OVER THE NORTHWESTERN QUADRANT, WITH INCREASING PRESSURE FROM THE 
NORTHWESTERLY VERTICAL WIND SHEAR. EIR IMAGERY SHOWS PERSISTENT LINEAR 
BANDING ALONG THE SOUTHEASTERN FLANK OF THE SYSTEM. MICROWAVE IMAGERY 
HAS BEEN SPARSE BUT AN EARLIER 120812Z WSF-M 37GHZ MICROWAVE IMAGE 
SHOWED IMPROVED CONVECTIVE BANDING OVER THE SOUTHERN QUADRANT WRAPPING 
INTO A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. A FORTUITOUS 121139Z 
ASCAT-B BULLSEYE IMAGE REVEALS A DEFINED CENTER WITH A SWATH OF 25 TO 
30 KNOT WINDS OVER THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL 
POSITION WITH MEDIUM CONFIDENCE. THE INITIAL INTENSITY REMAINS 
ASSESSED AT 35 KNOTS, WHICH IS CONSISTENT WITH THE ASCAT DATA AND KNES 
DVORAK ESTIMATE. CIMSS OBJECTIVE ESTIMATES RANGE FROM 28 TO 40 KNOTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTH-SOUTH ORIENTED LOW- TO MID-LEVEL
SUBTROPICAL RIDGE (STR) ENTRENCHED EAST AND NORTHEAST OF THE SYSTEM. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 40 KTS AT 121230Z
   CIMSS ADT: 39 KTS AT 121120Z
   CIMSS AIDT: 38 KTS AT 121120Z
   CIMSS D-PRINT: 28 KTS AT 121200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE DUAL-CHANNEL

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: TROPICAL STORM (TS) 06W IS STRUGGLING TO 
CONSOLIDATE AND IS NOT VERTICALLY ALIGNED. EIR SATELLITE IMAGERY 
CONTINUES THE SHOW THE PRESENCE OF VORTICAL HOT TOWERS WITHIN THE 
CONVECTIVE MASS, WITH CLOUD TOP TEMPERATURES IN THE -80C TO -82C 
RANGE. THERE IS STILL AN EXPECTATION THAT THE SYSTEM WILL CONSOLIDATE 
AND BECOME INCREASINGLY AXISYMMETRIC OVER THE NEXT 12 HOURS. AS THIS 
OCCURS, THE SYSTEM IS FORECAST TO TRACK IN A MORE CONSISTENT POLEWARD 
TRAJECTORY ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 36. 
AFTER TAU 36, A MAJOR SHORTWAVE TROUGH IS EXPECTED TO DEEPEN OVER THE 
KOREAN PENINSULA AND JAPAN, WHICH COULD LEAD TO A NORTH-NORTHWESTWARD 
TRACK CLOSER TO YOKOSUKA BEFORE THE SYSTEM RECURVES NORTHEASTWARD 
TOWARD THE KURIL ISLANDS. EXTRA-TROPICAL TRANSITION (ETT) WILL 
COMMENCE AS THE SYSTEM INTERACTS WITH THE MAJOR SHORTWAVE TROUGH NEAR 
TAU 48, WITH ETT COMPLETING BY TAU 72 AS THE SYSTEM BECOMES EMBEDDED
WITHIN THE MIDLATITUDE WESTERLIES AND ACCELERATES.   

MODEL DISCUSSION: THE 120600Z ECENS AND GEFS ENSEMBLES HAVE REMAINED 
STABLE, WITH A TIGHT GROUPING OF SOLUTIONS THROUGH TAU 48. BOTH 
ENSEMBLES SHOW THE LARGE MAJORITY OF SOLUTIONS OVER OR EAST OF
THE BOSO PENINSULA. WITH THE EXCEPTION OF THE UKMET ENSEMBLE MEAN
AND UKMET VORTEX TRACKER, THE MAJORITY OF THE DETERMINISTIC MODELS
REMAIN CLUSTERED EAST OF THE BOSO PENINSULA. DUE TO MODERATE
UNCERTAINTY IN THE TAU 24 TO TAU 48 GUIDANCE, POTENTIAL REMAINS FOR
TRACK SHIFTS CLOSER TO HONSHU OR SKIRTING THE EASTERN COAST.
ADDITIONALLY, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY
FORECAST, WITH UNCERTAINTY IN THE PEAK INTENSITY. COAMPS-TC (GFS)
SHOWS A PEAK OF 59 KNOTS AT TAU 24 WHILE HAFS-A SHOWS A PEAK OF 46
KNOTS.      

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