Tropical Storm KAMMURI Advisory Sat Sep 27

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (KAMMURI) WARNING
NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 17W (KAMMURI), LOCATED APPROXIMATELY 162 NM
EAST-NORTHEAST OF IWO TO, HAS TRACKED NORTHWESTWARD AT 12 KNOTS OVER
THE PAST SIX HOURS. MULTISPECTRAL IMAGERY (MSI) DEPICTS A SEMI-
EXPOSED, CONSOLIDATING, LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
SPIRAL BANDING WRAPPING INTO THE LLCC. A 262059Z SSMIS IMAGE SHOW
FRAGMENTED BANDING WARPING INTO A VERY LARGE CENTROID FEATURE,
RESEMBLING A LARGE MONSOON DEPRESSION. ADDITIONALLY, THE DEEP
CONVECTION ON THE WESTERN PERIPHERY OF THE SYSTEM HAS DISSIPATED
OVER THE PAST 6 HOURS. THE CURRENT POSITION IS BASED ON THE MSI
ANIMATION AND AFOREMENTIONED MICROWAVE IMAGERY WITH LOW CONFIDENCE
DUE TO THE BROAD NATURE OF THE CENTER AND MULTIPLE VORTICES VISIBLE
WITHIN THE CENTROID. THE INITIAL INTENSITY REMAINS AT 55 KNOTS BASED
ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES FROM
ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS
LOCATED IN A MARGINAL ENVIRONMENT WITH MODERATE (15 TO 25 KNOT)
SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) AND RADIAL OUTFLOW. TS 17W
IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THE STR WILL REMAIN THE DOMINANT STEERING MECHANISM FOR TS 17W
THROUGH TAU 48. TS KAMMURI IS FORECAST TO TRACK MORE NORTHWARD AFTER
TAU 12 AS IT CONTINUES TO ROUND THE STR AXIS AND BEGINS TO RE-CURVE
TO THE NORTHEAST, AHEAD OF AN APPROACHING MID-LATITUDE SHORTWAVE
TROUGH. A MODERATE UPPER-LEVEL ENVIRONMENT IS EXPECTED TO PERSIST
ALLOWING TS 17W SOME CONSOLIDATION, IF ANY, SLIGHTLY INTENSIFYING BY
TAU 24. EXPECT KAMMURI TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY
TAU 48, AS IT IS FORECASTED TO BE ABOVE THE RIDGE ACCESS AND BECOME
EMBEDDED IN THE MID-LATITUDE WESTERLIES WITH THE COMPLETION OF ETT
BY TAU 72. AVAILABLE MODEL GUIDANCE IS OVERALL IN FAIR AGREEMENT;
HOWEVER, THE OVERALL CONFIDENCE IN JTWC FORECAST TRACK IS LOW DUE TO
THE UNCERTAINTY IN ITS INITIAL POSITION.//
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