Tropical Storm RAMMASUN Advisory Tue Jul 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (RAMMASUN) WARNING NR 16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 09W (RAMMASUN), LOCATED APPROXIMATELY 487 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
THE SYSTEM HAS INCREASED TO TYPHOON STRENGTH AS THE LOW LEVEL
CIRCULATION CENTER (LLCC) HAS CONTINUED TO CONSOLIDATE WITH
INCREASED CENTRAL CONVECTION WHILE THE BANDING LOCATED ALONG THE
WESTERN AND SOUTHERN SEMI-CIRCLE HAVE BECOME MORE DEFINED. A 140549Z
PARTIAL SSMI 85GHZ ALSO SHOWS INCREASED CONSOLIDATION AND
STRENGTHENING AS THE SYSTEM HAS BECOME MORE TIGHTLY WRAPPED WHILE
THE CONVECTIVE STRUCTURE TO THE NORTH REMAINS SUPPRESSED. UPPER
LEVEL ANALYSIS REVEALS A NOW FAVORABLE ENVIRONMENT AS EQUATORWARD
OUTFLOW HAS BECOME MORE ESTABLISHED WHILE VERTICAL WIND SHEAR (VWS)
REMAINS AT LOW (05 TO 10 KNOTS) LEVELS. THE INITIAL POSITION IS
BASED UPON THE AFOREMENTIONED SATELLITE IMAGERY WITH INCREASED
CONFIDENCE. THE CURRENT INTENSITY HAS BEEN INCREASED TO 65 KNOTS
BASED ON THE INCREASED ORGANIZATION OBSERVED IN THE MSI LOOP WHILE
DVORAK ESTIMATES FROM ALL REPORTING AGENCIES HAVE INCREASED TO
TYPHOON STRENGTH (65 KNOTS). TY 09W REMAINS ON A WESTWARD TRACK
ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) ANCHORED
TO THE NORTH OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 09W IS FORECAST TO CONTINUE WESTWARD FOR THE NEXT 24 HOURS
ALONG THE SOUTHERN PERIPHERY OF THE ENTRENCHED STR. THE FAVORABLE
UPPER LEVEL ENVIRONMENT AND CONDUCIVE SEA SURFACE TEMPERATURES (SST)
WILL ALLOW FOR FURTHER INTENSIFICATION THROUGH THE NEXT 12 TO 18
HOURS BEFORE THE SYSTEM BEGINS TO INTERACT WITH LAND AND MAKE
LANDFALL BY TAU 24. AS THE SYSTEM TRACKS OVER LAND, A WEAKENING
TREND IS EXPECTED THROUGH TAU 48 UNTIL THE SYSTEM RE-EMERGES IN THE
SOUTH CHINA SEA. A SLIGHT REORIENTATION IN THE STR IS EXPECTED AFTER
TAU 36 WHICH WILL SLIGHTLY TURN TY 09W TO THE WEST-NORTHWEST. AFTER
TAU 48, THE SYSTEM IS FORECAST TO PROCEED FURTHER INTO THE MORE OPEN
WATERS OF THE SOUTH CHINA SEA WHERE THE INCREASED DISTANCE TO LAND,
FAVORABLE UPPER LEVEL SUPPORT AND WARM WATERS WILL CAUSE TY 09W TO
START RE-INTENSIFYING.
   C. IN THE EXTENDED TAUS, THE SYSTEM IS FORECAST TO CONTINUE WEST-
NORTHWESTWARD ACROSS THE SOUTH CHINA SEA TOWARDS NORTHERN HAINAN
ISLAND, MAKING LANDFALL BETWEEN TAU 96 AND 120 ACROSS THE LEICHOU
PENINSULA AND INTO MAINLAND CHINA. WARM SSTS, DECREASED VWS, AND
INCREASED OUTFLOW IN THE SOUTH CHINA SEA WILL ALLOW FOR FURTHER
INTENSIFICATION, REACHING 90 KNOTS PRIOR TO LANDFALL AND WEAKENING
THEREAFTER. MODEL GUIDANCE IS IN GOOD AGREEMENT WITH SOME
DIFFERENCES IN TRACK SPEED BUT IS OTHERWISE TIGHTLY GROUPED. DUE TO
THE INCREASED CONFIDENCE IN THE INITIAL POSITION AND OVERALL GOOD
AGREEMENT IN THE MODELS, THERE IS NOW HIGH CONFIDENCE IN THE
FORECAST TRACK. HOWEVER, THERE IS STILL SOME UNCERTAINTY IN THE
INTENSITY FORECAST DUE TO THE EXTENT OF THE WEAKENING ANTICIPATED
WITH THE LAND INTERACTION IN THE MID FORECAST.//
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