WDPN31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (KOTO) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.3N 113.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 352 NM SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION, AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NOW FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH
TROPICAL STORM (TS) 33W (KOTO). THE SYSTEM CAN BE SEEN RECOVERING
FROM A RECENT COMPLETE REMOVAL OF THE CENTRAL CONVECTIVE CORE, DUE TO
PRONOUNCED SOUTHEASTERLY VERTICAL WIND SHEAR (VWS). SINCE THEN,
CONVECTIVE BANDING IS APPEARING TO SLOWLY REDEVELOP, MAINLY OVER
THE NORTHWESTERN QUADRANT, AWAY FROM THE SHEAR AND DRY AIR ENTRANCE
REGION. ADDITIONAL ENVIRONMENTAL ANALYSIS REVEALS CONTINUOUS
MID-LEVEL DRY AIR ENTRAINMENT, THERMALLY FAVORABLE (28-29 C) SEA
SURFACE TEMPERATURES (SST) AND STRONG POLEWARD OUTFLOW. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE FULLY EXPOSED 
LLCC OBSERVED IN A VISIBLE SATELLITE IMAGERY LOOP. THE INITIAL 
INTENSITY OF 55 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 
COMBINATION OF AGENCY FIXES AND A 272229Z RCM-3 SAR WIND SPEED 
PRODUCT.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT WITH RIDGING
LOCATED TO THE NORTHEAST AND NORTHWEST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 45 KTS AT 272251Z
   CIMSS ADT: 47 KTS AT 272030Z
   CIMSS AIDT: 51 KTS AT 272030Z
   CIMSS D-MINT: 38 KTS AT 272249Z
   CIMSS D-PRINT: 33 KTS AT 280040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT OVER THE EASTERN AND SOUTHERN
QUADRANTS

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: WEAK AND COMPETING SYNOPTIC STEERING
MECHANISMS STILL IN PLACE WILL RESULT IN CONTINUOUS ERRATIC
OSCILLATIONS SOUTHWARD AND NORTHWARD ALONG THE OVERALL WESTWARD
TRAJECTORY OF TS KOTO. SHORTLY AFTER TAU 48 THE SUBTROPICAL RIDGE
(STR) CENTERED OVER SOUTHEAST ASIA IS EXPECTED TO DOMINATE THE
STEERING AND PROPEL THE SYSTEM TOWARDS LANDFALL OVER SOUTHEASTERN
VIETNAM. IN TERMS OF INTENSITY, THE SYSTEM WILL ENCOUNTER SLIGHTLY
LESS HOSTILE ENVIRONMENT, WITH DECREASING VWS. DRY AIR INTRUSION
WILL CONTINUE TO AFFECT THE STRUCTURE OF THE VORTEX, INHIBITING ANY
SIGNIFICANT INTENSIFICATION. AROUND TAU 24, A SHORT WINDOW OF
OPPORTUNITY OPENS UP, WITH LOWER VWS IMPACTS, OFFSET HOWEVER BY
CONTINUOUS DRY AIR ENTRAINMENT AND POTENTIAL IMPACT FROM UPWELLING
BRINGING COLDER WATER TO THE OCEAN SURFACE BENEATH THE STORM,
CAUSING A DECREASE IN CONVECTIVE POTENTIAL. JUST BEFORE TAU 96, VWS
IS EXPECTED TO INCREASE AGAIN RESULTING IN FURTHER WEAKENING.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
AGREEMENT, WITH MAJORITY OF THE MODELS DEPICTING A NORTHWESTWARD
TURN TO OCCUR VERY SOON. BETWEEN TAUS 48 AND 72 TS KOTO WILL REACH
THE PERIPHERY OF THE RIDGING CENTERED TO THE NORTHWEST AND BEGIN
TURNING TOWARDS VIETNAM AS INDICATED BY MAJORITY OF THE MODELS,
ALBEIT WITH A DIFFERING TIMELINE, INCREASING UNCERTAINTY. JTWC
TRACK FORECAST IS THEREFORE ASSESSED WITH MEDIUM CONFIDENCE. IN
TERMS OF INTENSITY, MODELS ARE SLOWLY COMING TO A BETTER AGREEMENT
WITH ALL PREDICTING FLUCTUATIONS AROUND 45-55 KTS OVER THE NEXT 72
HOURS. AFTER THAT, CONSENSUS MEMBERS INDICATE STEADY WEAKENING. AS
A RESULT, INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE.

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