WDXS32 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (ANGGREK) WARNING 
NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.2S 93.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 1261 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
CONVECTIVE STRUCTURES FLARING DIRECTLY OVER THE ASSESSED LOW-LEVEL
CIRCULATION (LLC) AND ATTEMPTING TO WRAP CYCLONICALLY AROUND THE
EASTERN SEMICIRCLE. AN 181531Z 89GHZ MICROWAVE PASS SHOWS THE
MAJORITY OF ASSOCIATED CONVECTION SLIGHTLY WRAPPED AROUND THE
NORTHERN SEMICIRCLE, WITH SHALLOW LOW-LEVEL BANDING CURVED INTO THE
CENTER FROM THE SOUTHEAST, WHICH SUPPORTS THE INITIAL POSITION WITH
MEDIUM CONFIDENCE. AN EARLIER 181209Z SYNTHETIC APERTURE RADAR
(SAR) PASS SUPPORTS INITIAL INTENSITY ASSESSMENT IN HIGH
CONFIDENCE, INDICATING A 45 KTS WIND RADII OF 75 NM ENCIRCLING THE
MAJORITY OF THE NOW-OBSCURED CIRCULATION CENTER, WITH THE EXCEPTION
OF THE NORTHWEST QUADRANT, BEING HEAVILY INFLUENCED BY A SURGE OF
INCREASING DRY AIR FROM THE WEST ATTEMPTING TO ENGULF TC 06S.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST AND
SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   FMEE: T3.5 - 55 KTS
   CIMSS SATCON: 51 KTS AT 181531Z
   CIMSS ADT: 37 KTS AT 181730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 06S IS SLOWLY
PROGRESSING GENERALLY TO THE SOUTHWEST ALONG AN EXTENSION OF THE
DEEP-LEVEL STEERING RIDGE TO THE SOUTHEAST THROUGH TAU 24.
FOLLOWING TAU 24, TC 06S WILL CONTINUE TO TRACK SLOWLY AND MORE
WESTWARD AND NORTHWESTWARD ALONG THE NORTHEASTERN EDGE OF THE
WELL-ESTABLISHED AND BUILDING STR TO THE SOUTH. TC 06S IS
FORECASTED TO INTENSIFY TO 50 KTS THROUGH TAU 12 AS A MARGINALLY
FAVORABLE ENVIRONMENT CONTINUES TO ALLOW FOR FAVORABLE OUTFLOW
POLEWARD AND EQUATORWARD; HOWEVER, THE CURRENT MARGINALLY FAVORABLE 
ENVIRONMENT CHARACTERIZED BY MODERATE DUAL OUTFLOW AND WARM SST OFFSET 
BY DRY AIR INTRUSION AND MODERATE VERTICAL WIND SHEAR (VWS) WILL ALLOW 
TC 06S TO MAINTAIN INTENSITY NEAR 45 TO 50 KTS UNTIL THE END OF THE 
FORECAST PERIOD.

MODEL DISCUSSION: GENERALLY, NUMERICAL MODEL GUIDANCE REMAINS IN
FAIR AGREEMENT SUPPORTING THE JTWC FORECAST TRACK THROUGH TAU 24.
AFTER TAU 24, MODEL GUIDANCE DIVERGES WITH CONTINUED AND INCREASING
UNCERTAINTY AS TC 06S IS FORECASTED TO TRACK WEST-NORTHWESTWARD
WITH A SLOW AND STEADY SPEED. THE LATEST ECMWF PROBABILISTIC
GUIDANCE INDICATES A SLOW PROGRESSION TO THE WEST-SOUTHWEST, WHILE
THE GFS TRACKER BECOMES ERRATIC IN EXACT CYCLONE PLACEMENT PAST TAU
36, BUT IS GENERALLY WESTWARD. FOLLOWING TAU 24, DRY AIR
ENTRAINMENT AND UNFAVORABLE VWS IS EXPECTED TO SIGNIFICANTLY LIMIT
ANY FURTHER INTENSIFICATION PAST 50 KTS, SLOWLY DECREASING
INTENSITY FOR TC 06S THROUGH THE END OF THE FORECAST PERIOD.   

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