Tropical Storm RAMMASUN Advisory Cu, 18.07.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (RAMMASUN) WARNING NR 30//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 09W (RAMMASUN), LOCATED APPROXIMATELY 232 NM SOUTH OF HONG
KONG, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) SHOWS TY 09W
CONTINUES TO INTENSIFY IN A FAVORABLE ENVIRONMENT WITH HIGH SEA
SURFACE TEMPERATURES (30 TO 31 DEGREES CELSIUS) AND STEADY IMPROVE-
MENTS IN THE EYEWALL STRUCTURE. THE CURRENT INTENSITY OF 120 KNOTS IS
BASED ON DVORAK ESTIMATES RANGING FROM 115 TO 127 KNOTS. UPPER LEVEL
ANALYSIS SHOWS A FAVORABLE ENVIRONMENT CHARACTERIZED BY VIGOROUS
EQUATORWARD OUTFLOW AND LOW (05 TO 10 KNOTS) VERTICAL WIND SHEAR. THE
INITIAL POSITION IS BASED UPON THE DEFINED EYE FEATURE IN THE EIR
LOOP WITH HIGH CONFIDENCE. TY 09W IS STEADILY TRACKING WEST-NORTHWEST
ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR)
NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
   B. TY 09W IS FORECAST TO REMAIN ON A GENERALLY WEST-NORTHWESTWARD
TRACK THROUGH THE REMAINDER OF THE FORECAST AS THE STR PERSISTS TO
THE NORTHWEST OF THE SYSTEM. TY 09W IS EXPECTED TO STRENGTHEN FOR
THE NEXT 12 HOURS BEFORE THE FRICTIONAL EFFECTS OF HAINAN ISLAND
BEGIN TO WEAKEN THE SYSTEM BY TAU 24. WEAKENING WILL PERSIST AFTER
TRACKING OVER THE NORTHERN HALF OF HAINAN ISLAND AND AS THE SYSTEM
BEGINS TO INTERACT WITH THE LUICHOW PENINSULA. ONCE TY 09W MAKES
LANDFALL IN THE BORDER REGION OF NORTHERN VIETNAM AND SOUTHERN
CHINA, A RAPID WEAKENING WITH COMPLETE DISSIPATION OF THE TROPICAL
SYSTEM IS EXPECTED BY TAU 72. NUMERIC MODEL GUIDANCE IS IN VERY
TIGHT AGREEMENT WITH THE TRACK FORECAST, WHICH IS POSITIONED WITH
HIGH CONFIDENCE, CLOSE TO THE MULTI-MODEL CONSENSUS.//
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