Tropical Storm RAMMASUN Advisory Wed Jul 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (RAMMASUN) WARNING NR 23//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 09W (RAMMASUN), LOCATED APPROXIMATELY 47 NM
WEST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY INDICATES TY 09W LOST ITS EYE FEATURE OVER THE PAST
SIX HOURS WHILE TRACKING ACROSS SOUTHERN LUZON, HOWEVER, TIGHTLY
CURVED BANDING REMAINS. THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS
NOW TRACKED OFF THE WESTERN COAST OF LUZON AND INTO THE SOUTH CHINA
SEA (SCS). THE INITIAL POSITION IS BASED ON THE EIR, AND SUPPORTED BY
A 152148Z SSMIS 91GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS
ASSESSED AT 90 KNOTS BASED ON A RANGE OF DVORAK CURRENT INTENSITY
ESTIMATES FROM PGTW AND RJTD, AND TAKES INTO ACCOUNT THE SLIGHT
DEGRADATION OF THE CONVECTIVE STRUCTURE. UPPER-LEVEL ANALYSIS
INDICATES NORTHEASTERLY VERTICAL WIND SHEAR HAS INCREASED SLIGHTLY TO
10-15 KNOTS, HOWEVER ROBUST OUTFLOW REMAINS IN PLACE. SEA SURFACE
TEMPERATURES (SSTS) IN THE SCS ARE SUPPORTIVE OF FURTHER
INTENSIFICATION. THE CYCLONE IS CURRENTLY TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
   B. TY 09W IS FORECAST TO REMAIN GENERALLY ON A WEST-NORTHWESTWARD
TRACK THROUGHOUT ITS LIFESPAN. AS THE SYSTEM TRACKS OVER THE OPEN
WATERS OF THE SCS, FAVORABLE UPPER LEVEL CONDITIONS AND SSTS WILL
ALLOW TY 09W TO REORGANIZE AND CONTINUE INTENSIFYING TO A PEAK OF
110 KNOTS BY TAU 48, PRIOR TO MAKING A SECOND LANDFALL ACROSS HAINAN
ISLAND. CONDITIONS ARE FORECAST TO REMAIN FAVORABLE AS THE SYSTEM
CROSSES INTO THE GULF OF TONKIN, ALLOWING TY 09W TO MAINTAIN ITS
TYPHOON STATUS PRIOR TO MAKING LANDFALL OVER VIETNAM.
   C. IN THE EXTENDED TAUS, TYPHOON RAMMASUN WILL MOVE INTO NORTHERN
VIETNAM AND RAPIDLY DISSIPATE DUE TO LAND INTERACTION. AVAILABLE
DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT,
LENDING HIGH CONFIDENCE IN THE FORECAST TRACK WHICH IS LAID VERY
CLOSE TO THE MULTI-MODEL CONSENSUS.//
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