Tropical Storm SONGDA Advisory Di, 11.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (SONGDA) WARNING NR 12//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 23W (SONGDA), LOCATED APPROXIMATELY 310 NM NORTHEAST
OF IWO TO, JAPAN HAS TRACKED  AT 06 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A SMALL PINHOLE EYE
STILL EVIDENT BUT APPEARS TO BE CLOSING. WATER VAPOR IMAGERY DEPICTS
CONTINUED INTERACTION WITH THE MID-LATITUDE WESTERLIES AND
ASSOCIATED MODERATE TO HIGH VERTICAL WIND SHEAR (VWS). A 102111Z
SSMIS 91GHZ IMAGE REVEALS A DEEP CONVECTIVE INNER CORE STILL
EVIDENT; HOWEVER, THE REMAINING CONVECTION HAS ELONGATED TO THE
NORTHEAST DUE TO THE SOUTHWESTERLY VWS. THE CURRENT POSITION IS
BASED ON THE PINHOLE EYE WITH HIGH CONFIDENCE. THE INTENSITY REMAINS
AT 100 KNOTS BASED ON UNCHANGED DVORAK CURRENT INTENSITY ESTIMATES
OF T5.5 (102 KNOTS). TY 23W IS TRACKING IN A MARGINALLY UNFAVORABLE
ENVIRONMENT DUE TO MODERATE VWS OFFSETTING THE STRONG POLEWARD
OUTFLOW WHICH IS CAUSING THE CONVECTIVE STRUCTURE TO WEAKEN. TY
SONGDA HAS SLOWED FORWARD SPEED AND IS BEGINNING TO TURN TO THE
NORTHEAST AS IT ROUNDS THE DEEP LAYERED SUB-TROPICAL RIDGE (STR)
AXIS.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY SONGDA WILL CONTINUE TURNING TO THE NORTHEAST AS IT TRACKS
NORTH OF 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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