WDXS31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING 
NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.3S 87.3E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 1000 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A HIGHLY
SYMMETRIC, QUASI-ANNULAR TC WITH A 10NM PINHOLE EYE. A 142257Z
SSMIS 91GHZ MICROWAVE IMAGE REVEALS A ROBUST EYEWALL WITH
NEGLIGIBLE CONVECTIVE STRUCTURES BEYOND THE ROUGHLY 170NM CENTRAL
DENSE OVERCAST (CDO). THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF
120 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK
INTENSITY ESTIMATES INDICATING 127KTS DUE TO RECENT COOLING CLOUD
TOPS AND WARMING EYE TEMPERATURES, WHILE AUTOMATED INTENSITY
ESTIMATES LIKE CIMSS ADT INDICATE CLOSER TO 119KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   KNES: T6.5 - 127 KTS
   DEMS: T6.5 - 127 KTS
   FMEE: T6.5 - 127 KTS
   CIMSS ADT: 119 KTS AT 142115Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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 11S (FREDDY) IS FORECAST TO CONTINUE ON A
GENERALLY WESTWARD TRACK FOR THE FORESEEABLE FUTURE. CURRENTLY IN A
MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE WESTWARD
OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS) AND WARM
(27-28 C) SEA SURFACE TEMPERATURES (SST) SOMEWHAT OFFSET BY THE
SURROUNDING DRY ENVIRONMENT. AS 11S CONTINUES TO TRANSIT ALONG THE
NORTHERN PERIPHERY OF THE STR, THE SYSTEM MAY CONTINUE TO INTENSIFY
THROUGH TAU 24, REACHING A POTENTIAL PEAK INTENSITY OF 130KTS.
AFTER TAU 48, THE SYSTEM WILL MEANDER SLIGHTLY POLEWARD OF THE 15TH
PARALLEL AS THE STR STRUGGLES TO REBUILD AFTER THE PASSAGE OF TC
13S. AFTER REACHING ITS PEAK INTENSITY, IF 11S CAN FEND OFF THE
SURROUNDING DRY ENVIRONMENT AND MAINTAIN A MOIST CORE, THERE WILL
BE MINIMAL WEAKENING THROUGH THE FORECAST PERIOD AS 11S TRANSITS
THE SOUTHERN INDIAN OCEAN.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT THROUGH
TAU 72 AND GOOD AGREEMENT THROUGH TAU 120, AS ALL MEMBERS ECHO THE
PERSISTENT WESTWARD TRACK. FOR THIS REASON THE JTWC TRACK FORECAST
IS PLACED INITIALLY WITH HIGH CONFIDENCE AND THE EXTENDED FORECAST
IS PLACED WITH MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE
IS IN POOR AGREEMENT, WITH AVNI, HWRF AND COAMPS-TC (NVGM)
INDICATING UNREALISTIC WEAKENING WHILE THE REMAINING MEMBERS
INDICATE CONTINUED INTENSIFICATION THROUGH TAU 24. AFTER TAU 24,
THE VARIOUS MEMBERS LEVEL OFF, LEAVING A LARGE ENVELOPE IN
SOLUTIONS. FOR THIS REASON THE JTWC INTENSITY FORECAST IS PLACED
ABOVE THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE. 

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