Tropical Storm PHANFONE Advisory Sun Oct 05

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (PHANFONE) WARNING
NR 23//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 18W (PHANFONE), LOCATED APPROXIMATELY 474 NM SOUTH OF
IWAKUNI, JAPAN, HAS TRACKED NORTHWESTWARD AT 10 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
THE SYSTEM HAS MAINTAINED A 35-NM EYE EVEN AS THE SPIRAL BANDING
HAVE SLIGHTLY LOOSENED THEIR WRAP INTO THE LOW- LEVEL CIRCULATION
CENTER. THE INITIAL POSITION IS BASED ON THE MSI LOOP AND ON A
040607Z 37H SSMI MICROWAVE EYE FEATURE WITH HIGH CONFIDENCE. THE
INITIAL INTENSITY OF 120 KNOTS IS BASED ON OVERALL ASSESSMENT OF
DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW, RJTD, AND KNES. UPPER-
LEVEL ANALYSIS INDICATES TY 18W IS LOCATED IN AN AREA OF STRONG
(GREATER THAN 30 KNOTS) VERTICAL WIND SHEAR (VWS). HOWEVER, THE VWS
IS OFFSET BY VIGOROUS OUTFLOW, ESPECIALLY ON THE POLEWARD SIDE THAT
IS BEING ENHANCED BY THE MID-LATITUDE WESTERLIES. THE CYCLONE IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
   B. TY 18W IS FORECAST TO BEGIN TRACKIMG NORTHWARD OVER THE NEXT 12
HOURS AS IT ROUNDS THE WESTERN PERIPHERY OF THE STR THEN SHOULD
ACCELERATE NORTHEASTWARD AS IT BEGINS EXTRA-TROPICAL TRANSITION. TY
18W IS EXPECTED TO BE RAPIDLY ABSORBED INTO THE BAROCLINIC ZONE.
INCREASING VWS AND COOLING SEA SURFACE TEMPERATURES WILL RAPIDLY
ERODE THE SYSTEM BUT WILL STILL BE A VERY INTENSE COLD-CORE LOW BY
TAU 48. THE AVAILABLE NUMERIC GUIDANCE IS IN TIGHT AGREEMENT AND
LENDS HIGH CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID
SLIGHTLY TO THE RIGHT OF AND FASTER THAN MODEL CONSENSUS TO OFFSET
KNOWN MODEL TENDENCIES.//
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