Tropical Storm CHAN-HOM Advisory wto., 06.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (CHAN-HOM) WARNING
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (CHAN-HOM), LOCATED APPROXIMATELY 167 NM
WEST-SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT
08 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) AND A 052335Z GMI 89 GHZ MICROWAVE IMAGE
REVEALS A DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION OVER THE EASTERN SEMICIRCLE AND EVIDENT CONVECTIVE
BANDING WRAPPING IN FROM THE NORTHWEST. A 052310Z ASCAT-A BULLSEYE
IMAGE SHOWS A DEFINED LLCC WITH A SWATH OF 45-49 KT WINDS TO THE
EAST, LENDING HIGH CONFIDENCE TO THE INITIAL POSITION. BASED ON THE
ASCAT DATA AND DVORAK CURRENT INTENSITY ESTIMATE OF T3.0 (45 KTS) BY
PGTW, THERE IS GOOD CONFIDENCE IN THE INITIAL INTENSITY OF 45 KTS.
TS 16W IS MOVING THROUGH AN ENVIRONMENT WHICH IS CONDUCIVE FOR
DEVELOPMENT WITH WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES
(SST), LOW (5-10 KT) VERTICAL WIND SHEAR (VWS), AND ESTABLISHED
EQUATORWARD AND POLEWARD OUTFLOW. THE SYSTEM IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO
THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 16W IS FORECAST TO TRACK GENERALLY NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF THE STEERING STR THROUGH TAU 72, STEADILY
INTENSIFYING TO A PEAK OF 80 KTS DUE TO CONTINUED LOW VWS AND WARM
SST. DURING THIS TIME, THE STEERING STR WILL BEGIN TO REORIENT.
UNCERTAINTY IN THIS REORIENTATION INDUCES UNCERTAINTY IN THE TIMING
OF THE RECURVE, INCREASING MODEL SPREAD TO 211 NM BY TAU 72. OVER
THE PAST SIX HOURS, THE MODEL SOLUTIONS, AND THUS FORECAST TRACK,
HAVE SHIFTED SLIGHTLY WESTWARD. BASED ON THE SPREAD, THERE IS ONLY
FAIR CONFIDENCE IN THE INITIAL PORTION OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, THE SYSTEM WILL TRACK FIRST NORTHWARD THEN ROUND
THE STR AXIS AND TURN TO A GENERALLY NORTHEASTWARD TRACK TOWARDS
KYUSHU. DUE TO HIGH (>20 KTS) VWS, TS 16W IS EXPECTED TO GRADUALLY
WEAKEN FOR THE REMAINDER OF THE FORECAST PERIOD TO AN INTENSITY OF
50 KTS BY TAU 120. TS 16W WILL BEGIN TO INTERACT WITH THE BAROCLINIC
ZONE DURING THIS TIME AND COMMENCE EXTRATROPICAL TRANSITION. IN THE
EXTENDED RANGE, THE ALONG-TRACK SPREAD HAS INCREASED AT TAU 120 DUE
TO THE UNCERTAINTY IN THE TIMING OF THE RECURVE. THUS, THERE IS ONLY
FAIR CONFIDENCE IN THE REMAINDER OF THE JTWC FORECAST TRACK.//
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