WDXS31 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01S (ONE) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.7S 94.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 119 NM WEST-NORTHWEST OF COCOS ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
PERSISTENT CONVECTION PARTIALLY OBSCURING A LOW LEVEL CIRCULATION
CENTER (LLCC) WITH TRANSVERSE BANDING ON ITS WESTERN SEMICIRCLE. A
290333Z METOP-C ASCAT IMAGE SHOWS A SMALL, SLIGHTLY ELONGATED LLCC
WITH A LARGE SWATH OF 35 KNOT WINDS WRAPPING INTO THE WESTERN
SEMICIRCLE WITH A FEW ISOLATED 40 KNOT WIND BARBS. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI AND ASCAT
IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE RECENT ASCAT IMAGERY.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP LAYER
SUBTROPICAL RIDGE (STR)

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 37 KTS AT 290540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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 01S IS IN THE PROCESS OF EXECUTING A
SOUTHWESTWARD TURN UNDER THE STEERING INFLUENCE OF A STR TO ITS
EAST. THE SYSTEM IS FORECAST TO TRACK GENERALLY SOUTHWESTWARD OVER
THE NEXT 24 HOURS IN WHICH TIME THE SYSTEM MAY REACH ITS PROJECTED
PEAK INTENSITY OF 45 KNOTS. AFTER TAU 24, THE SYSTEMS UPPER LEVEL
OUTFLOW WILL BEGIN TO DECLINE, RESULTING IN STAGNATING INTENSITIES
AS VERTICAL WIND SHEAR (VWS) BEGINS TO COUNTERACT OUTFLOW. BETWEEN
TAU 36 AND TAU 48 VWS INCREASES AND DRY AIR ENTRAINMENT BEGINS TO
ADD TO THE SYSTEMS DECLINING ENVIRONMENT. AFTER TAU 48 AS THE
SYSTEMS CONTINUES WEAKENING ITS STEERING MECHANISM WILL TRANSLATE
TO THE LOWER LEVEL WIND FIELD ASSOCIATED WITH A MID-LEVEL
ANTI-CYCLONE POLEWARD OF THE SYSTEM. EVENTUALLY STEADING UP ON A
GENERALLY WEST-NORTHWESTWARD COURSE THE SYSTEM WILL BEGIN TO MOVE
INTO AN ENVIRONMENT WHICH WILL BE MUCH LESS CONDUCIVE FOR FURTHER
DEVELOPMENT AS VERTICAL WIND SHEAR INCREASES ALONG WITH A
SUBSTANTIAL IN FLUX OF DRY AIR, UNTIL EVENTUAL DISSIPATION NEAR TAU
96.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH THE
JTWC FORECAST THROUGH TAU 48 WITH THE EXCEPTION OF NAVGEM AND HWRF
WHICH SHOW AN UNREALISTIC EASTWARD TRACK INTO THE STEERING RIDGE
BEFORE RETURNING WESTWARD. AFTER TAU 48 NUMERICAL MODELS BEGIN TO
SPREAD SLIGHTLY AS CROSS TRACK AND ALONG TRACK VARIABILITY BEGIN TO
ACCUMULATE. FOR THIS REASON THE JTWC FORECAST TRACK IS PLACED WITH
MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN
GENERALLY GOOD AGREEMENT WITH THE JTWC FORECAST WITH THE BULK OF
THE MODELS SHOWING A GENERAL INCREASE THROUGH TAU 12 AFTER WHICH
ALL MEMBERS BEGIN A DOWNWARD TREND THROUGH THE FORECAST PERIOD.
COAMPS-TC (NAVGEM) AND AHNI (GFS) BOTH INDICATE AN IMMEDIATE
WEAKENING TREND THAT IS INCONGRUOUS WITH THE BULK OF THE GUIDANCE.
FOR THIS REASON THE JTWC FORECAST INTENSITY IS PLACED WITH MEDIUM
CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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