MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (SONGDA)
WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 23W (SONGDA), LOCATED APPROXIMATELY 224 NM
SOUTH-SOUTHWEST OF MINAMI TORI SHIMA, HAS TRACKED WEST-NORTHWESTWARD
AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH CURVED BANDING OVER THE WESTERN SEMI-CIRCLE OF
THE LLCC. A 081653Z SSMI 85GHZ IMAGE DEPICTS SPIRAL BANDING WRAPPING
INTO A DEFINED CENTER, WHICH SUPPORTS THE CURRENT POSITION WITH GOOD
CONFIDENCE. 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 35 KNOTS BASED ON DVORAK ESTIMATES OF T2.5 (35 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 24 DUE TO IMPROVING
POLEWARD OUTFLOW ASSOCIATED WITH AN APPROACHING MIDLATITUDE
SHORTWAVE TROUGH AND IS EXPECTED TO REACH A PEAK INTENSITY OF 80
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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