Tropical Storm LIONROCK Advisory Wed Aug 24

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (LIONROCK) WARNING
NR 22//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 12W (LIONROCK), LOCATED APPROXIMATELY 346 NM
EAST OF KADENA AB, HAS TRACKED SOUTH-SOUTHWESTWARD AT 05 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH A FORMATIVE
EYE AND IMPROVED DEEP CONVECTIVE BANDING, WHICH PROVIDES GOOD
CONFIDENCE IN THE CURRENT POSITION. THIS CONSOLIDATION IS EVIDENT IN
A 230453Z SSMI 37GHZ IMAGE, WHICH SHOWS TIGHTLY-CURVED BANDING
WRAPPING INTO A MICROWAVE EYE FEATURE. THE CURRENT INTENSITY IS
ASSSESSED AT 55 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T3.5
(55 KNOTS) FROM BOTH KNES AND PGTW AS WELL AS A RECENT SATCON
ESTIMATE OF 50 KNOTS (23/0130Z). UPPER-LEVEL ANALYSIS INDICATES
ENHANCED POLEWARD OUTFLOW, AIDED BY A SHARP SHORTWAVE TROUGH OVER
CENTRAL JAPAN, AND GOOD EQUATORWARD OUTFLOW. TS 12W IS LOCATED
WITHIN A WEAK STEERING ENVIRONMENT BETWEEN THE DOMINANT WESTERN
SUBTROPICAL RIDGE (STR) AND EASTERN STR, AND IS DRIFTING GENERALLY
SOUTHWARD.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, HOWEVER, TRACK SPEEDS AFTER TAU 72
HAVE BEEN INCREASED SIGNIFICANTLY.
   B. TS 12W WILL REMAIN TRAPPED WITHIN THIS COMPETING STEERING
ENVIRONMENT WHILE DRIFTING SOUTH-SOUTHWESTWARD TO WESTWARD THROUGH
TAU 72. THE WESTERN STR IS EXPECTED TO REMAIN ENTRENCHED OVER THE
EAST CHINA SEA AND OKINAWA PROVIDING A BARRIER TO ANY SIGNIFICANT
WESTWARD MOVEMENT. IN FACT, ALL DYNAMIC MODELS SHOW A SLOW, QUASI-
STATIONARY MOTION THROUGH TAU 72 AND SHOW NO POSITION WEST OF 131E
LONGITUDE. TS 12W IS FORECAST TO GRADUALLY INTENSIFY UNDER FAVORABLE
CONDITIONS TO A PEAK OF 75 KNOTS BY TAU 72.
   C. IN THE EXTENDED TAUS, THE NEAR-EQUATORIAL RIDGE (NER) IS
FORECAST TO BUILD TO THE SOUTH OF TS 12W WHILE A DEEP MIDLATITUDE
TROUGH DEEPENS OVER JAPAN, ALLOWING THE SYSTEM TO ACCELERATE EAST-
NORTHEASTWARD. WHILE THE MODEL VORTEX TRACKERS DIFFER ON THE EXACT
NATURE OF THE TURN EASTWARD, THE TRACKERS ALL SHOW AN EASTWARD TURN
WITH DIFFERENT TRACK SPEEDS. DUE TO THE COMPLEXITY OF THE STEERING
ENVIRONMENT AND UNCERATINTY IN THE EASTWARD TURN, THERE IS LOW
CONFIDENCE IN JTWC FORECAST TRACK.//
NNNN
NNNN