Tropical Storm SONGDA Advisory Dom, 09-10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (SONGDA)
WARNING NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 23W (SONGDA), LOCATED APPROXIMATELY 246 NM
SOUTHWEST OF MINAMI TORI SHIMA, HAS TRACKED WEST-NORTHWESTWARD AT 15
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH TIGHTLY-CURVED BANDING WRAPPING INTO A DEFINED CENTER. A
082039Z SSMIS 37GHZ IMAGE DEPICTS A DEFINED MICROWAVE EYE FEATURE
WITH SPIRAL BANDING WRAPPING INTO THE LLCC. ANIMATED WATER VAPOR
IMAGERY REVEALS IMPROVING OUTFLOW WITH ENHANCED POLEWARD OUTFLOW
ASSOCIATED WITH THE TUTT TO THE NORTH. ADDITIONALLY, EQUATORWARD
OUTFLOW HAS IMPROVED AS THE BROAD UPPER-LOW TO THE SOUTHWEST HAS
WEAKENED. THE CURRENT INTENSITY IS ASSESSED AT 45 KNOTS BASED ON
DVORAK ESTIMATES OF T3.0 (45 KNOTS) FROM BOTH KNES AND PGTW. TS 23W
IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A.  NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 23W IS FORECAST TO TRACK NORTHWESTWARD THROUGH TAU 36 THEN
RE-CURVE NORTHEASTWARD AS IT ROUNDS THE WESTERN PERIPHERY OF THE
STR. TS SONGDA WILL RAPIDLY INTENSIFY AFTER TAU 12 DUE TO IMPROVING
POLEWARD OUTFLOW ASSOCIATED WITH AN APPROACHING MIDLATITUDE
SHORTWAVE TROUGH AND IS EXPECTED TO REACH A PEAK INTENSITY OF 90
KNOTS BY TAU 48.
   C. AFTER TAU 72, TS SONGDA WILL BEGIN EXTRA-TROPICAL TRANSITION
(ETT) AS IT BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES AND
THE ASSOCIATED STRONG BAROCLINIC ZONE. THE SYSTEM IS EXPECTED TO
WEAKEN AS IT ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND
ACCELERATES NORTHEASTWARD. TS 23W WILL COMPLETE ETT BY TAU 120 AS IT
GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE
MIDLATITUDE WESTERLY FLOW. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK.//
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