Tropical Storm KAMMURI Advisory Cts, 27.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (KAMMURI) WARNING
NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 17W (KAMMURI), LOCATED APPROXIMATELY 200 NM
EAST OF IWO TO, HAS TRACKED NORTH-NORTHWESTWARD AT 14 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY CONTINUES TO DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH SPIRAL BANDING OVER 600NM IN DIAMETER WRAPPING
INTO THE LLCC. A 261721Z SSMI AND 261703Z AMSU-B IMAGE SHOW
FRAGMENTED BANDING WARPING INTO A VERY LARGE CENTROID FEATURE,
RESEMBLING A LARGE MONSOON DEPRESSION. THE CURRENT POSITION IS
BASED ON THE EIR ANIMATION AND AFOREMENTIONED MICROWAVE IMAGERY
WITH LOW CONFIDENCE DUE TO THE BROAD NATURE OF THE CENTER. 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
FAVORABLE ENVIRONMENT WITH LOW (10 TO 15 KNOT) 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 TURN POLEWARD AFTER
TAU 24 AS IT CONTINUES TO ROUND THE STR AXIS AND BEGINS TO RE-CURVE
AHEAD OF AN APPROACHING MID-LATITUDE SHORTWAVE TROUGH. IN ADDITION
TO THE WARM SEA SURFACE TEMPERATURES, A FAVORABLE UPPER-LEVEL
ENVIRONMENT IS EXPECTED TO PERSIST ALLOWING TS 17W TO FURTHER
CONSOLIDATE AND REACH TYPHOON STRENGTH OVER THE NEXT 24 HOURS.
COMPARING THE LATEST FSU GFS CYCLONE PHASE SPACE DIAGRAM AND OTHER
TRACK DATA, 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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