Tropical Storm SONGDA Advisory вт, 11.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (SONGDA) WARNING NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 23W (SONGDA), LOCATED APPROXIMATELY 287 NM EAST-
NORTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTHWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS A DISTINCT WEAKENING AND ELONGATION TO THE CORE CONVECTIVE
STRUCTURE SURROUNDING A VERY SMALL 5-NM EYE. WATER VAPOR IMAGERY
SHOWS THAT THE TYPHOON HAS STARTED TO INTERACT WITH THE MID-LATITUDE
WESTERLIES AND ASSOCIATED MODERATE TO HIGH VERTICAL WIND SHEAR
(VWS). THE INCREASED VWS IS NOW OFFSETTING THE STRONG POLEWARD
OUTFLOW AND RELATIVELY WARM SEA SURFACE TEMPERATURES WHICH IS
RESPONSIBLE FOR THE RECENT WEAKENING. THE CURRENT POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE. THE INTENSITY HAS
BEEN DECREASED TO 100 KNOTS DUE TO THE SIGNIFICANT DETERIORATION IN
THE STORM STRUCTURE. TY SONGDA IS NEARING THE WESTERN AXIS OF THE
DEEP LAYERED SUB-TROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY SONGDA WILL CONTINUE TO MOVE NORTHWARD AND THEN TURN TO THE
NORTHEAST AS IT ROUNDS THE STEERING STR AXIS. AFTERWARDS THE TYPHOON
WILL RAPIDLY ACCELERATE NORTHEASTWARD AS IT EMBEDS WITHIN THE MID-
LATITUDE WESTERLY FLOW. EXPECT ENVIRONMENTAL CONDITIONS TO CONTINUE
TO DETERIORATE AS THE SYSTEM GAINS LATITUDE DUE TO VWS ABOVE 30
KNOTS AND SSTS DROPPING BELOW 26 CELSIUS NEAR TAU 36. TY 23W WILL
BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 24 AS IT INTERACTS
WITH THE BAROCLINIC ZONE AND COMPLETE ETT BY THE END OF THE FORECAST
PERIOD AS A STRONG COLD-CORE LOW. THERE IS HIGH CONFIDENCE IN THE
FORECAST DUE TO VERY TIGHT AGREEMENT IN ALL MODEL TRACKERS.//
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