WDXS33 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9S 103.8E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 434 NM EAST-SOUTHEAST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 14S (TALIAH) WITH AN ELONGATED LOW-LEVEL CIRCULATION
CENTER, OBSCURED BY CONVECTIVE BURSTS ALONG THE WESTERN PERIPHERY.
A 052244Z RCM-1 SAR IMAGE REVEALS THE ELONGATED NATURE OF THE
CIRCULATION, BUT ALSO REVEALS 65-70 KNOT WINDS IN THE NORTHERN
PERIPHERY. THERE IS A VERY SMALL PORTION OF THE IMAGE WHICH SHOWS
80-90 KTS WITHIN THE NORTHERN SEMICIRCLE, BUT THOSE ARE ANALYZED TO
BE ERRONEOUS AND NOT REPRESENTATIVE OF THE SYSTEM. ENVIRONMENTAL
ANALYSIS INDICATES THAT 14S IS IN A MARGINAL ENVIRONMENT
CHARACTERIZED BY MODERATE EQUATORWARD OUTFLOW, HIGH (25-30 KTS)
VERTICAL WIND SHEAR, AND WARM (27-28 C) SEA SURFACE TEMPERATURES.
THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
EXPOSED LOW-LEVEL CLOUDS WITHIN THE EASTERN PERIPHERY SEEN IN THE
ANIMATED MSI. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH LOW
CONFIDENCE BASED ON PERSISTENCE FROM THE SAR IMAGE, WHICH IS HIGHER
THAN WHAT AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES FROM
CIMSS INDICATE.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE MENTIONED SAR DATA.

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS ADT: 34 KTS AT 060600Z
   CIMSS AIDT: 39 KTS AT 060600Z
   CIMSS DPRINT: 36 KTS AT 060600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT ALONG THE EASTERN PERIPHERY.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 14S IS FORECAST TO TRACK WESTWARD, ALONG THE
NORTHERN PERIPHERY OF THE STR THROUGH TAU 48. AROUND TAU 48, THE
RIDGE BREAKS AND THE STEERING INFLUENCE BECOMES LESS DEFINED. AS A
RESULT, 14S WILL SLOW DOWN CONSIDERABLY AFTER TAU 48 AS IT ENTERS A
WEAK STEERING ENVIRONMENT. THIS WEAK STEERING ENVIRONMENT WILL
PERSIST THROUGH THE REMAINDER OF THE FORECAST PERIOD. REGARDING
INTENSITY, 14S IS FORECAST TO WEAKEN THROUGH TAU 24 AS VERTICAL
WIND SHEAR REMAINS HIGH AND DRY AIR INTRUDES ON THE VORTEX. AROUND
TAU 48, THE ENVIRONMENT WILL BECOME MORE FAVORABLE WITH LOWER SHEAR
AND A MOISTER ENVIRONMENT. THIS WILL CAUSE 14S TO REINTENSIFY
THROUGH THE REMAINDER OF THE FORECAST PERIOD TO AROUND 75 KTS AT
TAU 120. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AGREES THOUGH TAU 72
WITH 70 NM CROSS-TRACK SPREAD. AFTER TAU 72, MODELS DIVERGE
SIGNIFICANTLY WITH A 305 NM CROSS-TRACK SPREAD AT TAU 120. THIS IS
IN RESPONSE TO THE WEAK STEERING ENVIRONMENT AT THAT TIME. AS A
RESULT, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE
THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS
IN MODERATE AGREEMENT WITH ALL MODELS SUGGESTING REINTENSIFICATION
AFTER TAU 60. THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL
MEDIUM CONFIDENCE DUE TO UNCERTAINTIES WITH THE REINTENSIFICATION
PHASE.

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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