WDXS31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01S (ONE) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.7S 93.7E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 1295 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH PULSING DEEP
CONVECTION SHEARED OVER THE SOUTHERN SEMICIRCLE OF THE LLC. A
291817Z ATMS 88.2GHZ MICROWAVE IMAGE REVEALS AN OBLONG AREA OF DEEP
CONVECTION OVER THE SOUTHERN SEMICIRCLE WITH WEAK CONVECTIVE 
STRUCTURE ELSEWHERE. OVERALL, THERE IS LOW CONFIDENCE IN THE INITIAL 
POSITION DUE TO THE LACK OF HIGHER RESOLUTION MICROWAVE IMAGERY AND 
VISIBLE IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH 
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK ESTIMATES AND RECENT
SCATTEROMETER DATA. ENVIRONMENTAL CONDITIONS REMAIN MARGINALLY-
FAVORABLE WITH MODERATE TO HIGH NORTHERLY VERTICAL WIND
SHEAR OFFSET BY STRONG POLEWARD OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A LOW- TO
MID-LEVEL EXTENSION OF THE SUBTROPICAL RIDGE.  

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   APRF: T2.5 - 35 KTS
   CIMSS SATCON: 48 KTS AT 291511Z
   CIMSS ADT: 43 KTS AT 291750Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: TC 01S IS TRACKING TOWARD A BREAK IN THE
SUBTROPICAL RIDGE (STR) WITH A DEEP MIDLATITUDE TROUGH POSITIONED
TO THE SOUTH-SOUTHWEST, AND IS FORECAST TO DIP SOUTHWESTWARD
BRIEFLY BEFORE TURNING SHARPLY WEST-NORTHWESTWARD AFTER TAU 24.
AFTER TAU 24, THE AFOREMENTIONED MIDLATITUDE TROUGH WILL TRACK
EASTWARD AND A STRONG LOW- TO MID-LEVEL STR IS EXPECTED TO BUILD IN
TO THE SOUTH, WHICH WILL STEER THE SYSTEM WEST-NORTHWESTWARD
THROUGH THE FORECAST PERIOD. TC 01S SHOULD MAINTAIN AN INTENSITY
NEAR 40 KNOTS FOR THE NEXT 24 HOURS, HOWEVER, ENVIRONMENTAL
CONDITIONS WILL DEGRADE STEADILY AFTER TAU 24 WITH SIGNIFICANT DRY
AIR ENTRAINMENT, INCREASING NORTHERLY VWS AND MARGINALLY-FAVORABLE
SST VALUES AROUND 26C. TC 01S WILL, THEREFORE, DISSIPATE BY TAU 96
AND PERHAPS EARLIER.    

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A
100NM SPREAD IN SOLUTIONS AT TAU 72 LENDING HIGH CONFIDENCE TO THE
TRACK FORECAST. RELIABLE INTENSITY GUIDANCE UNANIMOUSLY SUPPORTS A
GRADUAL WEAKENING TREND TO 30 KNOTS OR LESS BY TAU 96 LENDING HIGH
CONFIDENCE TO THE INTENSITY FORECAST.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH
   INTENSITY 72-120 HR: HIGH//
NNNN