Tropical Storm SONGDA Advisory Mon Oct 10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (SONGDA)
WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 23W (SONGDA), LOCATED APPROXIMATELY 488 NM EAST-
SOUTHEAST OF IWO TO, HAS TRACKED NORTHWESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A
BANDING FEATURES BECOMING BETTER ORGANIZED WITH DEEP CENTRAL
CONVECTION. A 0534Z SSMIS 91 GHZ IMAGE SHOWS WEAK BANDING CONFINED
TO THE NORTH AND WESTERN PERIPHERIES WITH A MICROWAVE EYE STARTING
TO FORM WITHIN A SMALL BUT DEEP CONVECTIVE BAND WRAPPING IN FROM THE
SOUTHEAST, GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. THE
INITIAL INTENSITY IS ASSESSED AT 45 KNOTS AND IS BASED ON THE
CURRENT STRUCTURE AND WITHIN THE UPPER ENVELOPE OF DVORAK ESTIMATES
RANGING FROM T2.5 TO T3.0 (35 TO 45 KNOTS). VERTICAL WIND SHEAR IS
VERY LOW AND A MODEST POLEWARD OUTFLOW CHANNEL HAS BEEN ESTABLISHED.
SSTS ARE VERY FAVORABLE NEAR 29 CELSIUS. CURRENTLY TS SONGDA IS
TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE POSITIONED TO THE NORTH.
3. FORECAST REASONING.
   A.  NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS SONGDA WILL CONTINUE TO TRACK NORTHWEST ALONG THE EDGE OF
THE CURRENT STEERING RIDGE FOR THE NEXT 24 HOURS. ENVIRONMENTAL
CONDITION ARE EXPECTED TO IMPROVE ALLOWING FOR GRADUAL
INTENSIFICATION AS IT APPROACHES THE RIDGE AXIS AROUND TAU 24.
BEYOND TAU 24 THE TRACK WILL SLOW DOWN SLIGHTLY AS IT ROUNDS THE
RIDGE AXIS AND FURTHER INTENSIFY TO 90 KNOTS BY TAU 48 AS OUTFLOW
BECOMES ENHANCED FROM AN APPROACHING SHORTWAVE TROUGH. SHORTLY
THEREAFTER TS SONGDA IS EXPECTED TO ACCELERATE ALONG A NORTHEASTWARD
TRACK AS IT INTERACTS WITH THE TROUGH AND WESTERLY JET. WEAKENING
WILL OCCUR AS VERTICAL WIND SHEAR INCREASES AND THE SYSTEM GAINS
BAROCLINICITY WHILE TRANSITIONING INTO AN EXTRATROPICAL SYSTEM. TS
SONGDA IS EXPECTED TO BECOME FULLY EXTRATROPICAL BY TAU 96. DYNAMIC
MODEL GUIDANCE IS IN VERY GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO
THE FORECAST TRACK.//
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