WDXS33 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH)      
WARNING NR 030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.7S 82.6E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 1145 NM SOUTHWEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD,
EXPOSED LOW-LEVEL CIRCULATION, WITH PERSISTENT DEEP CONVECTION
DISPLACED OVER THE SOUTHERN PERIPHERY. THE 151527Z ASCAT-B 25KM AND
151525Z ASCAT UHR IMAGES SUPPORT THE INITIAL POSITION, INITIAL
INTENSITY, AND INITIAL WIND RADII WITH HIGH CONFIDENCE. A 151618Z
MHS 89GHZ MICROWAVE IMAGE REVEALS A GENERALLY UNIMPRESSIVE SIGNATURE, 
WITH WEAKLY DEFINED SHALLOW BANDING WRAPPING INTO THE BROAD CENTER, 
AND LIMITED DEEP CONVECTION SHEARED OVER 130NM TO THE SOUTHWEST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT, WITH A
SUBTROPICAL RIDGE (STR) TO THE EAST AND SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T1.5 - 25 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 25 KTS AT 151800Z
   CIMSS AIDT: 33 KTS AT 151800Z
   CIMSS D-PRINT: 30 KTS AT 151800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 30+ KTS
   SST: 24-25 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: EXTENSIVE DRY AIR OVER THE NORTHERN AND EASTERN
                  QUADRANTS.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 14S IS EXPECTED TO 
CONTINUE TRACKING SLOWLY SOUTHWESTWARD THROUGH TAU 72 WITHIN A
COMPETING STEERING ENVIRONMENT, WITH A LOW-LEVEL STR POSITIONED TO
THE EAST AND SOUTH. HIGH VERTICAL WIND SHEAR (VWS), COOL SST VALUES
(22-25C), AND HIGH (25-35 KNOTS) VWS WILL CONTINUE TO HINDER ANY
SIGNIFICANT CORE CONVECTIVE DEVELOPMENT. HOWEVER, DEEP CONVECTION
SHOULD PERSIST OVER THE SOUTHERN QUADRANT DUE TO ROBUST POLEWARD
OUTFLOW THROUGH TAU 72. THE SYSTEM WILL CONTINUE TO TRACK UNDER
SUBTROPICAL WESTERLIES WHILE MAINTAINING A COMPACT CORE OF STRONG
WINDS AND GALE-FORCE WINDS PRIMARILY OVER THE SOUTHERN SEMICIRCLE.
AFTER TAU 72, THE SYSTEM SHOULD GRADUALLY WIND DOWN WHILE DRIFTING
WESTWARD UNDER A STRONG HIGH BUILDING TO THE SOUTH.   

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 72, WITH A 75NM CROSS-TRACK SPREAD IN SOLUTIONS 
AT TAU 72. AFTER TAU 72, GUIDANCE DIVERGES WITH INCREASING 
UNCERTAINTY IN THE EXACT TRACK. PROBABILISTIC GUIDANCE FROM THE ECMWF 
AND GFS ENSEMBLES (EPS, GEFS) INDICATES A SIMILAR SPREAD THROUGH TAU 
72, WITH LARGE SPREAD, HIGH UNCERTAINTY REVEALED AFTER TAU 72 LENDING 
LOW CONFIDENCE TO THE JTWC EXTENDED PERIOD TRACK FORECAST. RELIABLE 
INTENSITY GUIDANCE SUPPORTS A STEADY WEAKENING TREND THROUGH THE 
FORECAST PERIOD.  

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