Tropical Storm SIX Advisory Tue Aug 11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX)
WARNING NR 004//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (SIX), LOCATED APPROXIMATELY 232
NM EAST-NORTHEAST OF IWO TO, HAS TRACKED WESTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH
ASSOCIATED CONVECTION SHEARED OVER THE WESTERN SEMICIRCLE. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED
LLCC IN THE MSI AND THE LOW LEVEL CIRCULATION FEATURE PRESENT IN A
100634Z SSMIS 91GHZ IMAGE. THE INITIAL INTENSITY IS PLACED WITH HIGH
CONFIDENCE BASED ON MULTIAGENCY DVORAK CURRENT INTENSITY ESTIMATES
OF T1.5 (25 KTS, RJTD) AND T2.0 (30 KTS, PGTW), A 100610Z ADVANCED
DVORAK TECHNIQUE CURRENT INTENSITY ESTIMATE OF T2.5 (35 KTS) AND A
100540Z SATCON INTENSITY ESTIMATE OF 39 KTS.  TS 06W IS TRACKING
WESTWARD THROUGH A MARGINAL ENVIRONMENT FOR DEVELOPMENT WITH
MODERATE TO STRONG (20-25 KTS) VERTICAL WIND SHEAR (VWS) OFFSET BY
VERY WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURES (SST). INCREASING
EASTERLY VWS HAS SHEARED THE ASSOCIATED CONVECTION TO THE WEST AND
LEFT THE LLCC FULLY EXPOSED. UPPER LEVEL SUPPORT ASSOCIATED WITH A
NARROW TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO THE WEST,
HOWEVER, IS HELPING TO SUSTAIN THE SYSTEM IN THE PRESENCE OF THE
INCREASING VWS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 06W WILL CONTINUE TRACKING GENERALLY WESTWARD ALONG THE
SOUTHERN EDGE OF THE STR THROUGHOUT THE 96 HOUR FORECAST. THE
ENVIRONMENT WILL BECOME INCREASINGLY UNFAVORABLE AS VERTICAL WIND
SHEAR INDUCED BY STRONG EASTERLY FLOW ALOFT PERSISTS. DESPITE THE
PERSISTENT SHEAR, PASSAGE OVER WARM WATER AND A FAVORABLE OUTFLOW
PATTERN IN THE NEAR-TERM SHOULD ALLOW THE SYSTEM TO REMAIN INTACT
AS A WEAK TROPICAL STORM OR TROPICAL DEPRESSION THROUGH TAU 48 AND
BY TAU 72 WILL BEGIN TO DISSIPATE OVER WATER.
   C. TS 06W IS EXPECTED TO WEAKEN TO 20 KTS BY TAU 96 DUE TO THE
HOSTILE SHEAR ENVIRONMENT AND DISSIPATE OVER WATER AT THAT TIME.
NUMERICAL MODEL SOLUTIONS REMAIN IN TIGHT AGREEMENT WITH MINIMAL
SPREAD IN SOLUTIONS THROUGH THE ENTIRE FORECAST PERIOD. THE TIGHT
AGREEMENT OF MODEL SOLUTIONS LENDS HIGH CONFIDENCE TO THE OVERALL
96 HOUR JTWC FORECAST TRACK.//
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