Tropical Storm SONGDA Advisory 12 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 23W (SONGDA) WARNING NR
15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 23W (SONGDA), LOCATED APPROXIMATELY 556 NM
EAST-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A VERY SYMMETRIC CORE STRUCTURE WITH A RESURGENCE IN
DEEP CONVECTION SURROUNDING A SHARP 12NM EYE. ALTHOUGH THE SYSTEM IS
NORTH OF THE SUB-TROPICAL RIDGE (STR) AXIS, IT HAS GONE THROUGH A
PERIOD OF RAPID INTENSIFICATION OVER THE PAST 12 HOURS. THIS IS DUE
TO THE CYCLONE MOVING IN-PHASE WITH THE 25 TO 30 KNOT SOUTHWESTERLY
VERTICAL WIND SHEAR, REDUCING ITS OVERALL IMPACTS TO THE STORM.
WATER VAPOR IMAGERY SHOWS AN ENHANCED POLEWARD OUTFLOW CHANNEL INTO
THE STRONG MID-LATITUDE WESTERLY FLOW. THE CURRENT POSITION IS BASED
ON THE EYE FEATURE WITH HIGH CONFIDENCE. THE INCREASE IN INTENSITY
IS BASED ON THE INTENSE CORE STRUCTURE OF THE CYCLONE WHICH IS
READILY APPARENT IN AN 111538Z AMSR-2 89GHZ MICROWAVE IMAGE SHOWING
AN INTENSE RED RING FULLY SURROUNDING THE EYE. ADDITIONALLY, ALL
AGENCIES ARE REPORTING DVORAK INTENSITY ESTIMATES OF T6.5 (127
KNOTS). STY 23W IS BEGINNING TO ACCELERATE NORTHEASTWARD ALONG THE
NORTHWESTERN PERIPHERY OF THE DEEP LAYERED STR.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST TRACK PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, THE CURRENT AND
FORECASTED INTENSITY HAS BEEN INCREASED BASED ON THE RECENT RAPID
INTENSIFICATION.
   B. STY SONGDA WILL CONTINUE ACCELERATING NORTHEASTWARD AS IT
EMBEDS DEEPER WITHIN THE MID-LATITUDE WESTERLY FLOW. THE CYCLONE
WILL SOON ENCOUNTER VWS OVER 40 KNOTS AND, ALTHOUGH IT WILL BE IN-
PHASE WITH THE MOVEMENT OF STY 23W, WILL OFFSET THE OUTFLOW AND
BEGIN THE FINAL WEAKENING PHASE. STY SONGDA WILL BEGIN EXTRA-
TROPICAL TRANSITION (ETT) OVER THE NEXT 12 HOURS AND COMPLETE ETT BY
THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN
TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE FORECAST TRACK.//
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