WDXS31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (BATSIRAI) 
WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.6S 41.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 169 NM SOUTH-SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED,
MALFORMED AND BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION SHEARED TO THE SOUTHEAST BY MODERATE (20 KNOTS)
NORTHWESTERLY VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI. TC 08S IS
STRUGGLING TO REINTENSIFY DUE TO THE BROAD NATURE OF THE LLCC AND
SIGNIFICANT DRY AIR ENTRAINMENT. ADDITIONALLY, VWS IS HINDERING
CONVECTIVE DEVELOPMENT OVER THE CORE DESPITE ROBUST POLEWARD
OUTFLOW EVIDENT IN ANIMATED WATER VAPOR IMAGERY. A 070706Z ASCAT-B
PARTIAL IMAGE SHOWS AN ASYMMETRIC WIND FIELD WITH 35-40 KNOT WINDS
OVER THE SOUTHERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL INTENSITY
WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A LOW- TO
MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   CIMSS SATCON: 39 KTS AT 071056Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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 08S IS FORECAST TO ACCELERATE SOUTHWARD
ALONG THE WESTERN PERIPHERY OF THE LOW- TO MID-LEVEL STR THROUGH
TAU 36. SLIGHT INTENSIFICATION TO 45 KNOTS IS EXPECTED BETWEEN TAU
12 AND TAU 24 THEN WEAKENING AS VWS INCREASES AND SEA SURFACE 
TEMPERATURES (SST) COOL TO 25C. AFTER TAU 36, THE SYSTEM WILL BEGIN 
INTERACTING WITH THE LEADING EDGE OF AN APPROACHING MIDLATITUDE 
TROUGH AND COMMENCE SUBTROPICAL TRANSITION. AS TC 08S TURNS SOUTH-
SOUTHEASTWARD AFTER TAU 36, IT SHOULD COMPLETE SUBTROPICAL 
TRANSITION NEAR THE SUBTROPICAL JET AND TRACK OVER COOLER SST (23-
24C) WITH VWS INCREASING TO 30-35 KNOTS. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT THROUGH
TAU 48 WITH AN 80NM SPREAD IN SOLUTIONS AT TAU 48, THEREFORE, THERE
IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. RELIABLE INTENSITY
GUIDANCE TO INCLUDE HWRF AND THE JTWC INTENSITY CONSENSUS (ICNW)
ALSO SUPPORT THE JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE,
PRIMARILY DUE TO THE POSSIBILITY THAT THE SYSTEM MAY WEAKEN DUE TO
THE EXTENSIVE DRY AIR ENTRAINMENT AND FAIL TO INTENSIFY DURING THE
EARLY PORTION OF THE FORECAST. 

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