WDXS31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (DUDZAI) WARNING NR 
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.9S 57.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 280 NM SOUTH-SOUTHEAST OF ST DENIS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 14S (DUDZAI) WITH A WELL-DEFINED AND COMPACT LOW-LEVEL
CIRCULATION CENTER (LLCC). CONVECTION REMAINS RELATIVELY SHALLOW
AND CONFINED TO A SMALL POCKET OVER THE CENTER OF THE LLCC. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
DEFINED LOW-LEVEL CLOUDS TIGHTLY WRAPPING INTO THE CENTER IN
ANIMATED MSI. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIX AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. CIMSS ADT ESTIMATES ARE ANALYZED
TO BE UNDERESTIMATING INTENSITY DUE TO THE WEAK CONVECTIVE
STRUCTURE OF THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES THAT 14S
IS IN A MARGINAL ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD
OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR, AND BORDERLINE
(26-27 C) SEA SURFACE TEMPERATURES. DRY AIR COMPLETELY SURROUNDS
THE VORTEX, BUT IT HAS CONTINUED TO MAINTAIN A MOIST INNER-CORE.

INITIAL WIND RADII BASIS: PERSISTENCE WITH SLIGHT ADJUSTMENTS BASED
ON THE OBJECTIVE BEST TRACK

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   FMEE: T4.0 - 65 KTS
   FIMP: T4.0 - 65 KTS
   CIMSS SATCON: 51 KTS AT 201026Z
   CIMSS ADT: 32 KTS AT 201130Z
   CIMSS AIDT: 39 KTS AT 201130Z
   CIMSS D-MINT: 52 KTS AT 200936Z
   CIMSS D-PRINT: 48 KTS AT 201130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR COMPLETELY SURROUNDING THE SYSTEM

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 14S IS FORECAST TO TRACK SOUTHWARD, ALONG
THE WESTERN PERIPHERY OF THE STR TO THE EAST, THROUGH TAU 12. AFTER
TAU 12, 14S IS FORECAST TO ACCELERATE SOUTHEASTWARD AS IT ROUNDS
THE RIDGE AXIS AND BEGIN TO INTERACT WITH THE STRONG MID-LATITUDE
WESTERLIES ASSOCIATED WITH THE JET. 14S IS FORECAST TO MAINTAIN ITS
CURRENT INTENSITY THROUGHOUT THE FORECAST PERIOD DUE TO THE EXTREME
POLEWARD OUTFLOW INTO THE JET OFFSETTING THE INCREASING SHEAR, DRY
AIR ENTRAINMENT, AND COOLING SEA SURFACE TEMPERATURES. 14S IS
FORECAST TO BEGIN EXTRATROPICAL TRANSITION AT TAU 12 AS IT CROSSES
THE 26 C ISOTHERM AND BEGINS TO BECOME EMBEDDED WITHIN THE
BAROCLINIC ZONE. SEA SURFACE TEMPERATURES ARE EXPECTED TO RAPIDLY
DROP AFTER TAU 12 AND ARE EXPECTED TO BE AROUND 22-23 C AT TAU 24. AS 
A RESULT, 14S IS FORECAST TO COMPLETE THE TRANSITION INTO A STORM-
FORCE EXTRATROPICAL CYCLONE NEAR TAU 24.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT WITH A MERE 55 NM CROSS-TRACK SPREAD AT TAU 24 WITH
MINIMAL ALONG-TRACK SPREAD. THE JTWC TRACK FORECAST IS PLACED NEAR
THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
IS IN GOOD AGREEMENT ON A STEADY INTENSITY OVER THE NEXT 24 HOURS.
THE JTWC INTENSITY FORECAST IS ALSO PLACED CLOSE TO THE CONSENSUS
WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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