WDPS31 PGTW 072100 COR
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10P (NAT)
WARNING NR 007 CORRECTION//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5S 151.5W
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 162 NM SOUTHWEST OF PAPEETE, TAHITI
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 10P (NAT) HAVING COMPLETELY DECOUPLED FROM UPPER-LEVEL
SUPPORT, LEAVING A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC) OVER THE LAST 12 HOURS. EXTENSIVE SHALLOW BANDING IS
OBSERVED WRAPPING INTO THE LLCC UP TO 250NM TO THE SOUTHWEST.  SEA
SURFACE TEMPERATURES (SST) REMAIN VERY FAVORABLE (29-30C). 
HOWEVER, POOR DIVERGENCE ALOFT AND STRONG VERTICAL WIND SHEAR WILL
LIKELY INHIBIT ANY INTENSIFICATION OVER THE NEXT 24 HOURS. THE 
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED AN EXPOSED LLCC 
OBSERVABLE IN A 171820 GOES-W VISIBLE SATELLITE IMAGE. THE INITIAL 
INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 
071620Z SMOS WINDSPEED IMAGE AND THE OBJECTIVE AND SUBJECTIVE 
INTENSITY GUIDANCE LISTED BELOW.

INITIAL WIND RADII BASIS: SMOS DATA 

CURRENT STEERING MECHANISM: NER TO THE NORTHWEST AND STR TO THE
SOUTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   PHFO: T3.0 - 45 KTS
   CIMSS ADT: 47 KTS AT 071740Z
   CIMSS AIDT: 41 KTS AT 072010Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 30+ KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: PREVIOUSLY, TC 10P WAS FORECAST TO 
DISSIPATE AS A TC OVER WATER. THE CURRENT FORECAST CHANGES THIS 
PHILOSOPHY TO A SUBTROPICAL TRANSITION BEGINNING NEAR TAU 24, 
COMPLETING TRANSITION NOT LATER THAN TAU 36. THE FORECAST INTENSITY 
HAS ALSO BEEN SIGNIFICANTLY ADJUSTED TO ACCOUNT FOR THE SHIFT IN 
PHILOSOPHY.

FORECAST DISCUSSION: TC 10P IS FORECAST TO TRACK EASTWARD THROUGH
THE FORECAST INTERVAL AS IT EXPERIENCES STEERING INFLUENCE OF THE STR
TO THE SOUTHWEST (TAU 00) AND SOUTH (TAU 24). THE INTENSITY
FORECAST HOLDS TC 10P AT CURRENT INTENSITY THROUGH TAU 24, AND THEN
GRADUALLY RISING THEREAFTER TO 50KTS BY TAU 36. ANALYSIS OF THE
SYSTEMS STRUCTURE AND ENVIRONMENTAL PARAMETERS IN GLOBAL NUMERICAL
GUIDANCE AND TC PHASE DIAGRAMS SHOW THE SYSTEM TRANSITIONING TO A
SUBTROPICAL CYCLONE NEAR TAU 24, HAVING FULLY COMPLETED SUBTROPICAL
TRANSITION BY TAU 36. THIS IS CHARACTERIZED, IN THIS INSTANCE, AS
HAVING A WEAK TEMPERATURE GRADIENT, PROMINENT COLD AIR
ADVECTION (POLEWARD) AND WARM AIR ADVECTION (EQUATORWARD), AND
GROWING SUBSTANTIALLY ASYMMETRIC AND SHALLOW BY TAU 36.

MODEL DISCUSSION: GLOBAL NUMERICAL GUIDANCE IS IN EXCEPTIONAL
AGREEMENT THAT TC 10P WILL TRACK EASTWARD THROUGH THE FORECAST
INTERVAL, SHOWING A TIGHT CROSS-TRACK SPREAD OF JUST 37NM BY TAU
36. INTENSITY GUIDANCE, WITH THE EXCEPTION OF GFS, SUGGESTS TC 10P
WILL PERSIST AT NEAR 45KTS INTENSITY AND EVENTUALLY (NEAR TAU 24)
EXPERIENCE SLIGHT REINTENSIFICATION TO TAU 36 AS THE SYSTEM BECOMES 
FULLY SUBTROPICAL.

FORECAST CONFIDENCE:
   TRACK 0 - 36 HR: HIGH
   INTENSITY 0 - 36 HR: MEDIUM//
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