WDIO31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06B (MANDOUS) 
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.9N 81.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 88 NM SOUTHEAST OF CHENNAI, INDIA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
TIGHTLY WRAPPED TROPICAL STORM WITH FLARING CONVECTION IN THE
WESTERN SEMICIRCLE. A 091120Z 91GHZ SSMIS MICROWAVE IMAGE REVEALS
ISOLATED DEEP CONVECTION TO THE NORTHWEST OF THE LOW LEVEL
CIRCULATION CENTER (LLCC) AND TIGHTLY WRAPPING LOW LEVEL CLOUD
LINES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON EIR AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON SLIGHT SPREADING OF
INTENSITY GUIDANCE. AS THE SYSTEM CONTINUES TO WEAKEN, THE
SUBJECTIVE NATURE OF DVORAK INTENSITY ESTIMATES WILL BECOME MORE
PRONOUNCED. AT THE MOMENT AGENCY DVORAK ESTIMATES CURRENTLY RANGE
BETWEEN T2.0 AND T3.5 WHILE CIMSS ADT SHOWS 41KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS SATCON: 54 KTS AT 090815Z
   CIMSS ADT: 41 KTS AT 091215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: LAND INTERACTION WITH INDIA

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 06B MANDOUS IS FORECAST TO TRANSITION FROM
TRACKING NORTH-NORTHWESTWARD TO WEST-NORTHWESTWARD AS THE STR TO
THE NORTHEAST REORIENTS OVER THE NEXT 12 HOURS. DURING THIS TIME
VERTICAL WIND SHEAR (VWS) AND LAND INTERACTION WILL INCREASE
RESULTING IN STEADY WEAKENING. AFTER MAKING LANDFALL SOUTH OF
CHENNAI NEAR TAU 12, THE SYSTEM WILL THEN RAPIDLY WEAKEN AS IT
CONTINUES WESTWARD OVER INDIA. BY TAU 24 THE SYSTEM WILL BE TORN
APART OVER SOUTHEASTERN INDIA UNTIL FULLY DISSIPATING BY TAU 36.  

MODEL DISCUSSION: WITH THE EXCEPTION OF HWRF TO THE NORTH AND
COAMPS-TC (NVGM VERSION) TO THE SOUTH, NUMERICAL MODELS ARE IN GOOD
AGREEMENT THAT 06B WILL MAKE LANDFALL NEAR TAU 12 JUST SOUTH OF
CHENNAI, BEFORE PROCEEDING INLAND UNTIL DISSIPATION BY TAU 36. FOR
THIS REASON THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM
CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS ALSO IN GOOD
AGREEMENT WITH ALL MEMBERS INDICATING A WEAKENING TREND THROUGH THE
FORECAST PERIOD. FOR THIS REASON THE JTWC INTENSITY FORECAST IS
PLACED WITH HIGH CONFIDENCE.

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