WDXS31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.7S 66.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 491 NM EAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TC
CYCLONE (TC) 09S (NINE) RAPIDLY CONSOLIDATING WITH INTERMITTENTLY
EXPLOSIVE CONVECTION CENTRALLY LOCATED OVERHEAD OF SHALLOW
LOW-LEVEL BANDING WRAPPING TIGHTLY INTO THE ASSESSED LOW-LEVEL
CIRCULATION. SEA SURFACE TEMPERATURES ARE VERY HIGH BETWEEN 29C AND
30C WHILE VERTICAL WIND SHEAR (VWS) BETWEEN 10 AND 15 KTS.
EXCELLENT DIVERGENCE ALOFT IS MOST PREVALENT THROUGHOUT SOUTHERN
SEMI-CIRCLE OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON METEOSAT-9 EIR ANIMATION LOOP. THE
INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE TO THE NORTHWEST
AND A DEEP-LAYER SHORTWAVE TROUGH EMBEDDED IN THE LONGWAVE PATTERN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 09S IS FORECAST TO BECOME QUASI-STATIONARY
THROUGH TAU 48 AS COMPETING STEERING MECHANISMS INFLUENCE INITIAL
TRACK MOTION. FOLLOWING TAU 48, TC 09S IS EXPECTED TO TRACK
SOUTHEASTWARD THROUGH TAU 120 AS THE EMBEDDED SHORTWAVE TROUGH
WITHIN THE MID-LATITUDE LONGWAVE PATTERN PROGRESSES EASTWARD. AS
ENVIRONMENTAL PARAMETERS REMAIN FAVORABLE THROUGH TAU 48, THE
TROPICAL CYCLONE IS FORECAST TO GRADUALLY INTENSIFY TO NEAR 50 KTS
AND MAINTAIN INTENSITY INTO THE REMAINDER OF THE FORECAST PERIOD
DUE TO COMPETING FAVORABLE TRACK SPEEDS WITH A GRADUAL DECAY IN
ENVIRONMENTAL INFLUENCES.  

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT TC 09S WILL TRACK GENERALLY QUASI-STATIONARY THROUGH
TAU 48 AS COMPETING STEERING MECHANISMS SLOW THE GENERAL TO THE
SOUTHEAST. THE JTWC TRACK CONSENSUS AT TAU 72 DISPLAYS A
CROSS-TRACK SPREAD OF 75NM LENDING MEDIUM CONFIDENCE TO THE TAU
0-72 INTERVAL, WHILE THE ALONG-TRACK SPREAD IS 218NM, CONVEYING
LOW-CONFIDENCE IN TRACK SPEED DURING THE 0-72 TAU INTERVAL. THE
GREATEST UNCERTAINTY AMONG THE JTWC INTENSITY CONSENSUS MEMBERS
PRESENTS ITSELF AT TAU 72, WITH A 20 KTS SPREAD, CONVEYING MEDIUM
CONFIDENCE AT TAU 72. HOWEVER, BY TAU 108, INTENSITY CONSENSUS
MEMBERS CONVERGE TO A SPREAD OF JUST 5 KTS. 

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