Tropical Storm IN-FA Advisory mar, 24-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (IN-FA) WARNING NR 26//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 27W (IN-FA), LOCATED APPROXIMATELY 742 NM SOUTHWEST
OF IWO TO, JAPAN HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A
FURTHER ELONGATION TO THE CLOUD STRUCTURE AS THE SYSTEM SLOWS AND
PRESSES AGAINST THE LEADING EDGE OF AN APPROACHING MID-LATITUDE
TROUGH. THE TYPHOON HAS REFORMED A 10-NM CLOUD FILLED EYE WHICH
SUPPORTS THE CURRENT POSITION WITH HIGH CONFIDENCE. THE WATER VAPOR
LOOP SHOWS A STRONG POLEWARD OUTFLOW CHANNEL ENHANCED BY THE MID-
LATITUDE WESTERLY FLOW. A 230341Z AMSR-2 89GHZ MICROWAVE IMAGE SHOWS
SHALLOW TIGHT SPIRAL BANDING WRAPPING INTO A SMALL MICROWAVE EYE
FEATURE WITH THE BULK OF CONVECTION SHEARED ALONG THE NORTHEASTERN
QUADRANT DUE TO MODERATE SOUTHWESTERLY VERTICAL WIND SHEAR (VWS).
THE INITIAL INTENSITY HAS BEEN HELD AT 90 KNOTS BASED ON UNCHANGED
DVORAK INTENSITY ESTIMATES OF T5.0 (90 KNOTS) FROM PGTW AND RJTD. TY
27W IS APPROACHING THE DEEP LAYERED SUB-TROPICAL RIDGE (STR) AXIS
AND HAS STARTED TO TURN MORE POLEWARD.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 27W WILL CONTINUE TO TURN MORE POLEWARD OVER THE NEXT 12 TO
24 HOURS AS IT ROUNDS THE STR AXIS. INCREASING INTERACTION WITH THE
APPROACHING MID-LATITUDE TROUGH WILL LEAD TO A NORTHEASTWARD
ACCELERATION INTO THE BAROCLINIC ZONE THROUGH THE REMAINDER OF THE
FORECAST PERIOD. ENVIRONMENTAL CONDITIONS WILL CONTINUE TO
DETERIORATE AS VWS RAPIDLY INCREASES DUE TO THE STRONG WESTERLY
WINDS FROM THE APPROACHING TROUGH. TY IN-FA WILL BEGIN EXTRA-
TROPICAL TRANSITION (ETT) NEAR TAU 72.
   C. IN THE EXTENDED TAUS, TY 27W WILL CONTINUE TO ACCELERATE
NORTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF THE STEERING STR.
TY 27W WILL CONTINUE ETT AS IT EMBEDS DEEPER INTO THE MID-LATITUDE
WESTERLY FLOW AND WILL COMPLETE ETT BY THE END OF THE FORECAST
PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT, LENDING TO
HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.//
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