Tropical Storm CHAMPI Advisory Sat Oct 17

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (CHAMPI) WARNING NR 16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 25W (CHAMPI), LOCATED APPROXIMATELY 467 NM SOUTH OF
IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM
HAS SIGNIFICANTLY INTENSIFIED AS IT DEVELOPED A 15-NM EYE. THE
INITIAL POSITION IS BASED ON THE EYE FEATURE WITH HIGH CONFIDENCE.
THE INITIAL INTENSITY OF 80 KNOTS IS BASED ON AN OVERALL ASSESSMENT
OF DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER-LEVEL ANALYSIS
INDICATES THE SYSTEM IS LOCATED IN AN AREA OF LOW VERTICAL WIND
SHEAR (VWS) AND GOOD EQUATORWARD OUTFLOW. THE CYCLONE IS TRACKING
ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR) TO THE NORTH-NORTHEAST.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY CHAMPI WILL CONTINUE TO TRACK NORTHWESTWARD OVER THE NEXT 24
HOURS UNDER THE INFLUENCE OF THE STR. AFTERWARDS, AS THE STR RECEDES,
THE SYSTEM WILL TAKE A MORE POLEWARD TRACK AND ROUND THE RIDGE AXIS.
EXPECT AN INCREASE IN INTENSITY THROUGH TAU 48 AS TY 25W GAINS
IMPROVED POLEWARD OUTFLOW, PEAKING AT 100 KNOTS. WITH THE SYSTEM
BEING NORTH OF THE RIDGE AXIS BY TAU 48, IT WILL TRACK TO THE
NORTHEAST ALONG THE NORTHWESTERN PERIPHERY OF THE STR. EXPECT SOME
DECAY OF THE SYSTEM BEYOND THIS TIME AS WATERS COOL AND VWS
INCREASES.
   C. IN THE EXTENDED TAUS, TY CHAMPI WILL REMAIN ON A NORTHEASTWARD
TRAJECTORY AND CONTINUE TO WEAKEN. BY TAU 120, IT WILL BEGIN
EXTRA-TROPICAL TRANSITION AS IT ENTERS THE COLD BAROCLINIC ZONE.
NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH, LENDING
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS LAID CLOSE TO THE
MULTI-MODEL CONSENSUS.//
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