Tropical Storm KUJIRA Advisory 27.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 15W (FIFTEEN), LOCATED APPROXIMATELY 447
NM WEST OF WAKE ISLAND, HAS TRACKED NORTHWESTWARD AT 08 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS DEEP CONVECTION OVER THE SOUTHERN AND EASTERN
SEMICIRCLES WITH FORMATIVE BANDING WRAPPING INTO THE CONSOLIDATING LOW
LEVEL CIRCULATION CENTER (LLCC). A 262323Z METOP-C PARTIAL ASCAT IMAGE
REVEALS A SWATH OF 30 KT WINDS WRAPPING AROUND THE EASTERN SEMICIRCLE
OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE
BASED ON THE ASCAT IMAGE AND A 262229Z MHS 89 GHZ MICROWAVE IMAGE
WHICH SHOWS CONVECTIVE BANDING ALONG THE EASTERN SEMICIRCLE. AN UPPER
LEVEL LOW TO THE NORTHWEST CONTINUES TO HINDER THE DEVELOPMENT OF DEEP
CONVECTION OVER THE NORTHWESTERN QUADRANT AS OBSERVED IN THE MSI. THE
INITIAL INTENSITY IS SET AT 30 KTS, HEDGED SLIGHTLY HIGHER THAN MULTI-
AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T1.5 (25 KTS) AND
SUPPORTED BY A 270001Z ADVANCED DVORAK TECHNIQUE ESTIMATE OF T2.0 (30
KTS) AND THE AFOREMENTIONED ASCAT DATA. TD 15W REMAINS IN A MODERATELY
CONDUCIVE ENVIRONMENT FOR DEVELOPMENT, CHARACTERIZED BY LOW (<15 KT)
VERTICAL WIND SHEAR (VWS) AND WARM (29-30 CELSIUS) SEA SURFACE
TEMPERATURES (SST). THE EFFECTS OF THE UPPER LEVEL LOW ARE BEING
OFFSET BY THE POINT SOURCE LOCATED OVER THE SYSTEM WHICH IS ENHANCING
DIFFLUENCE ALOFT. TD 15W IS TRACKING NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 15W IS FORECAST TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 36
AS IT STEADILY INTENSIFIES DUE TO CONTINUED CONDUCIVE SST AND LOW VWS.
AROUND TAU 36, TD 15W WILL BEGIN TO ROUND THE STR AXIS WITH THE
APPROACH OF A DEEP MIDLATITUDE TROUGH, TURNING FIRST NORTHWARD THROUGH
TAU 48 AND THEN NORTH-NORTHEASTWARD THROUGH TAU 72. NUMERICAL MODEL
GUIDANCE IN IS TIGHT AGREEMENT REGARDING THE TIMING OF THE RECURVE
WITH A CROSS-TRACK SPREAD OF 100 NM AT TAU 36. AFTER TD 15W ROUNDS THE
STR AXIS, IT WILL BEGIN EXTRATROPICAL TRANSITION (ETT) AS IT INTERACTS
WITH THE BAROCLINIC ZONE AROUND TAU 60. THE SYSTEM IS FORECAST TO
INTENSIFY TO A PEAK INTENSITY OF 75 KTS BY TAU 72. HOWEVER, THE
SYSTEM?S PEAK INTENSITY MAY OCCUR EARLIER, AROUND TAU 60. DUE TO THE
LOW MODEL SPREAD, THERE IS GOOD CONFIDENCE IN THE NEAR TERM JTWC TRACK
FORECAST.
   C. AFTER TAU 72, INCREASING VERTICAL WIND SHEAR AND RAPIDLY COOLING
(<26 CELSIUS) SST WILL CAUSE THE SYSTEM TO QUICKLY WEAKEN THROUGH THE
REMAINDER OF THE FORECAST PERIOD. TD 15W WILL TURN TO AN EAST-
NORTHEASTWARD TRACK ALONG THE PERIPHERY OF THE AFOREMENTIONED STR. BY
TAU 96, THE SYSTEM GAIN FRONTAL CHARACTERISTICS AS IT COMPLETES ETT
AND BECOMES EMBEDDED IN THE JET FLOW. NUMERICAL MODEL GUIDANCE IS IN
EXCELLENT AGREEMENT THROUGH THE EXTENDED FORECAST WITH A 106 NM SPREAD
AT TAU 72. FURTHERMORE, THE 26/18Z ECMWF ENSEMBLE SOLUTIONS ARE IN
GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD. THUS, THERE IS OVERALL
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN
NNNN