WDPS31 PGTW 030900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 18P (EIGHTEEN) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.2S 175.0E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 423 NM EAST-NORTHEAST OF KINGSTON IS.
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
EXPANSIVE SYSTEM WITH THE CENTRAL CONVECTION MAINTAINING ON THE 
POLEWARD AND EASTERN SIDE WITH EXTENSIVE AND ROBUST EASTWARD OUTFLOW. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON LOW CLOUD
TRACING AND A 030310Z GMI 37GHZ IMAGE. THE INITIAL INTENSITY IS SET 
WITH LOW CONFIDENCE DUE TO LACK OF SUPPORTING DATA. ANALYSIS INDICATES 
A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE VWS OFFSETTING THE
STRONG EASTWARD OUTFLOW AND WARM SST.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) TO THE
NORTH AND SUBTROPICAL RIDGE TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   NFFN: T3.0 - 45 KTS
   CIMSS SATCON: 42 KTS AT 030228Z
   CIMSS ADT: 37 KTS AT 030540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG EASTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 18S WILL REMAIN QUASI STATIONARY (QS) UP TO 
TAU 24 AS THE NER RECEDES AND THE SUBTROPICAL RIDGE (STR) BUILDS IN 
FROM THE SOUTH AND EAST. ONCE THE NEW STEERING IS ASSUMED FROM THE STR 
NEAR TAU 24, THE STR WILL DRIVE THE SYSTEM WEST-SOUTHWESTWARD AGAINST 
THE FLOW. CONCURRENTLY, THE VERTICAL WIND SHEAR WILL INCREASE 
SIGNIFICANTLY AND WEAKEN THE STRENGTH OF THE SYSTEM UNTIL DISSIPATION 
BY TAU 48 IF NOT SOONER. THE PEAK INTENSITY FOR TC 18P HAS ALREADY 
BEEN REACHED AT 40KTS IN THE MARGINALLY FAVORABLE ENVIRONMENT. 
INCREASED VWS AND CONVECTION DECOUPLING TO THE EAST WILL REDUCE THE 
SYSTEM BELOW THE JTWC WARNING CRITERIA STARTING AFTER TAU 36 AND WILL 
DISSIPATE BY TAU 48, OR SOONER.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL AGREEMENT WITH
THE TRACK FORECAST; HOWEVER, GIVEN THE UNCERTAINTY DURING THE QS
MOTION, THERE IS LOW CONFIDENCE IN THE INITIAL JTWC TRACK FORECAST
ON THIS SYSTEM. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   INTENSITY 0 - 72 HR: LOW//
NNNN