WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 33W (KOTO) WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1N 113.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 364 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
DESPITE ROBUST WESTWARD AND POLEWARD OUTFLOW, TYPHOON (TY) 33W IS
STRUGGLING TO MAINTAIN ITS CONVECTIVE CORE. ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY DEPICTS AN ASYMMETRIC CENTRAL DENSE OVERCAST (CDO), 
WITH A TIGHT THERMAL GRADIENT ALONG THE EASTERN EDGE OF THE CDO 
ASSOCIATED WITH THE HIGH (25-30 KNOTS) SOUTHEASTERLY VERTICAL WIND 
SHEAR (VWS). IN ADDITION TO THE HIGH VWS, DRY AIR ENTRAINMENT OVER THE 
EASTERN QUADRANT IS AIDING IN WEAKENING THE SYSTEM. THE DETERIORATING 
CONVECTIVE STRUCTURE IS CLEARLY EVIDENT IN A 270542Z ATMS 89GHZ 
MICROWAVE IMAGE, WHICH SHOWS SHALLOW BANDING WRAPPING INTO A WEAK LOW-
LEVEL CIRCULATION CENTER (LLCC) POSITIONED ON THE EASTERN EDGE OF THE 
DWINDLING CORE CONVECTION. BASED ON THE WEAKENED STRUCTURE, THE 
INITIAL INTENSITY HAS BEEN DECREASED TO 70 KNOTS, WHICH IS IN CLOSER 
AGREEMENT WITH THE CIMSS OBJECTIVE INTENSITY ESTIMATES RANGING FROM 59 
TO 78 KNOTS. SUBJECTIVE INTENSITY ESTIMATES APPEAR TO BE TOO HIGH AND 
ARE BASED ON EITHER THE CDO METHOD OR EMBEDDED CENTER METHOD YIELDING 
DATA-T ESTIMATES OF T4.5-5.0 (77-90 KNOTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN WITH SYSTEM
LOCATED BETWEEN A BROAD EASTERN SUBTROPICAL RIDGE (STR) TO THE EAST
AND A BROAD STR TO THE WEST OVER SOUTHEAST ASIA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T5.0 - 90 KTS
   CIMSS SATCON: 66 KTS AT 270544Z
   CIMSS ADT: 65 KTS AT 270530Z
   CIMSS AIDT: 59 KTS AT 270530Z
   CIMSS D-MINT: 78 KTS AT 270544Z
   CIMSS D-PRINT: 70 KTS AT 270630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT OVER THE EASTERN QUADRANT

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: HIGH VWS IS EXPECTED TO PERSIST THROUGH TAU 36
TO TAU 48, WHICH WILL LEAD TO A STEADY WEAKENING TREND THROUGH TAU
48. THE SYSTEM WILL TRACK SLOWLY NORTHWARD ALONG THE WESTERN
PERIPHERY OF THE EASTERN STR, WITH A SHARP WESTWARD TURN THROUGH
TAU 120 AS THE SYSTEM ENCOUNTERS THE WEAK EXTENSION OF THE WESTERN
STR. A BRIEF PERIOD OF RELAXED VWS OCCURS BETWEEN TAU 48 AND TAU
96, HOWEVER, DRY AIR ENTRAINMENT AND UPWELLING COOLER WATER ARE 
EXPECTED TO HINDER DEVELOPMENT. AFTER TAU 96, VWS INCREASES TO HIGH 
LEVELS AIDING IN FURTHER WEAKENING.  

MODEL DISCUSSION: DUE TO THE COMPETING STEERING ENVIRONMENT, THE
270000Z GEFS RUN SHOWS A WIDE CHAOTIC SPREAD, WITH A MORE DEFINITIVE 
WESTWARD TRACK OVER VIETNAM AFTER TAU 120. THE 270000Z EPS RUN IS IN 
BETTER AGREEMENT BUT INDICATES SIGNIFICANT UNCERTAINTY THROUGH TAU 
120. DETERMINISTIC GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 72, WITH 
A TIGHTER WESTWARD TRACK GROUPING OF SOLUTIONS AFTER TAU 72. THERE IS 
LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO THE SLOW TRACK 
AND POTENTIAL FOR UPWELLING COOLER WATER TO WEAKEN THE SYSTEM.    

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: MEDIUM//
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