WDXS31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (ASHLEY) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.4S 80.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 619 NM SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH THE ASSOCIATED
CONVECTION BEING DISPLACED TO THE SOUTHWEST. THIS DISPLACEMENT IS
CAUSED BY STRONG (30-35 KTS) UPPER-LEVEL WIND FLOW FROM THE
NORTH-NORTHEAST. A BULLSEYE 270340Z METOP-B ASCAT PASS, WHICH SHOWS
A DEFINED LLCC SURROUNDED PREDOMINATELY BY 25 KNOT WIND BARBS WITH
AN AREA OF 40 KNOT WINDS IN THE SOUTHWESTERN REGION AND 35 KNOT
WINDS IN THE SOUTHEASTERN SEMI-CIRCLE. TROPICAL CYCLONE 02S IS IN A
MARGINALLY UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY STRONG (30-35
KTS) POLEWARD OUTFLOW ALOFT, OFFSET BY NOMINALLY WARM (25-26 C)
SEAS SURFACE TEMPERATURES (SSTS), AND STRONG (20-25 KTS) VERTICAL
WIND SHEAR (VWS). THE INITIAL POSITION AND INITIAL INTENSITY ARE
PLACED WITH HIGH CONFIDENCE BASED ON THE MSI LOOP, THE AVERAGE OF
MULTIPLE AGENCY DVORAK ESTIMATES, AND THE PREVIOUSLY MENTIONED
ASCAT IMAGE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA FROM 270340Z METOP-B
ASCAT.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) LOCATED TO THE
SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   FMEE: T2.0 - 30 KTS
   CIMSS ADT: 39 KTS AT 270615Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR DOWNSTREAM OF FORECAST TRACK

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC ASHLEY WILL CONTINUE ON A
WEST-SOUTHWESTWARD TRACK AS IT MOVES ALONG THE NORTHWEST SECTOR OF
THE STR POSITIONED TO THE SOUTHEAST. TC ASHLEY APPEARS TO HAVE
ALREADY PEAKED AT 40 KNOTS, AND WILL NOW BEGIN WEAKENING AS IT
TRANSITS WEST-SOUTHWEST INTO A MORE UNFAVORABLE ENVIRONMENT, MARKED
BY COOLER SSTS, HIGHER VWS, AND DRIER AIR SURROUNDING THE LLCC.
AFTER TAU 12, TC 02S WILL MAKE A SOUTHWEST TURN AND TRACK INTO EVEN
COOLER WATERS, WHILE THE CONVECTION CONTINUALLY IS STRIPPED AWAY
FROM THE CENTER. AT TAU 24 THE SYSTEM WILL BEGIN DISSIPATING OUT
OVER THE SOUTHERN INDIAN OCEAN FAR FROM ANY LANDMASS AND COMPLETE
DISSIPATION BY TAU 36 IF NOT SOONER DUE TO THE HARSH ENVIRONMENT.

MODEL DISCUSSION: THE TRACK MODEL CONSENSUS MEMBERS ARE IN TIGHT
AGREEMENT THROUGHOUT THE FORECAST PERIOD WITH A MERE 36NM SPREAD AT
TAU 12, INCREASING TO AN OVERALL SPREAD OF 120 NM BY TAU 36 AS THE
LLCC WEAKENS. THE TIGHT AGREEMENT IN CONSENSUS LENDS HIGH
CONFIDENCE IN THE FORECAST TRACK. THE SAME STORY IS TRUE FOR
INTENSITY MODEL GUIDANCE. THERE IS ONLY A SPREAD OF 5 KNOTS BETWEEN
THE HIGHEST INTENSITY OF HWRF, AND LOWEST COAMPS THROUGH THE
DURATION OF THE FORECAST PERIOD, LENDING OVERALL HIGH CONFIDENCE IN
THE JTWC INTENSITY FORECAST.

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