Tropical Storm PHANFONE Advisory 05.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (PHANFONE) WARNING NR 26//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 18W (PHANFONE), LOCATED APPROXIMATELY 326 NM SOUTH
OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
35-NM RAGGED EYE WITH WEAKENED SPIRAL BANDING. A 042320Z SSMIS
MICROWAVE IMAGE CONTINUES TO SHOW A ROUND SIGNATURE WITH A WELL-
DEFINED MICROWAVE EYE. THE CURRENT POSITION IS BASED ON THE EYE
FEATURE ON THE MSI AND SSMIS IMAGE WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY HAS DECREASED TO 100 KNOTS BASED ON AN OVERALL ASSESSMENT
OF DVORAK CURRENT INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES
AND WEAKENING TREND. UPPER-LEVEL ANALYSIS INDICATES TY 18W IS
LOCATED IN AN AREA OF STRONG (GREATER THAN 30 KNOTS) VERTICAL WIND
SHEAR (VWS) OFFSET BY VIGOROUS OUTFLOW, ESPECIALLY ON THE POLEWARD
SIDE THAT IS BEING ENHANCED BY THE MID-LATITUDE WESTERLIES. TY 18W
IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 18W WILL CONTINUE TO ROUND THE WESTERN PERIPHERY OF THE STR
AND ACCELERATE NORTHEASTWARD AS IT STARTS EXTRA-TROPICAL TRANSITION
BY TAU 12. TY 18W IS EXPECTED TO BE QUICKLY ABSORBED INTO THE
BAROCLINIC ZONE. INCREASING VWS AND COOLING SEA SURFACE TEMPERATURES
WILL RAPIDLY ERODE THE SYSTEM BUT WILL STILL BE A VERY INTENSE STORM
FORCE COLD-CORE LOW BY THE END OF THE FORECAST PERIOD. THE AVAILABLE
NUMERIC GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE
TO THE JTWC TRACK FORECAST THAT IS LAID SLIGHTLY TO THE RIGHT OF AND
FASTER THAN MULTI-MODEL CONSENSUS.//
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