Tropical Storm DOKSURI Advisory Qua, 13-09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (DOKSURI)
WARNING NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 21W (DOKSURI), LOCATED APPROXIMATELY 255 NM WEST
OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A ROBUST CONVECTIVE MASS CENTRALLY LOCATED OVER A
LOW LEVEL CIRCULATION CENTER (LLCC). A 122300Z 91 GHZ SSMIS
MICROWAVE IMAGE SHOWS DEEP CONVECTIVE BANDING WRAPPING AROUND THE
WESTERN SEMICIRCLE AND INTO A RAGGED MICROWAVE EYE FEATURE. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
MICROWAVE IMAGE. THE INITIAL INTENSITY OF 45 KNOTS IS HEDGED ON THE
UPPER END OF MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES RANGING
FROM T2.5 TO T3.0 (35-45 KNOTS) FROM RJTD AND PGTW RESPECTIVELY.
ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW (10-
15 KNOTS) VERTICAL WIND SHEAR (VWS) AND IS TRACKING THROUGH VERY
WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES (SSTS). THE OUTFLOW
PATTERN HAS IMPROVED AS THE SYSTEM NOW HAS A STRONGER EQUATORWARD
OUTFLOW CHANNEL AND HAS WEAK POLEWARD OUTFLOW. TS 21W IS TRACKING TO
THE WEST-NORTHWEST UNDER THE INFLUENCE OF AN EXTENSION OF THE SUB-
TROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 21W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD UNDER THE
INFLUENCE OF THE STR THROUGH TAU 72. THE IMPROVING ENVIRONMENT WILL
ALLOW FOR A PERIOD OF RAPID INTENSIFICATION OVER THE NEXT 24 HOURS
AS THE SYSTEM TRACKS THROUGH VERY WARM SSTS AND LOW VWS. THE SYSTEM
IS FORECAST TO REACH A PEAK INTENSITY OF 80 KNOTS AT TAU 48. AFTER
TAU 48, THE SYSTEM WILL BEGIN TO INTERACT WITH LAND AND START A
GRADUAL WEAKENING TREND, MAKING LANDFALL IN NORTHERN VIETNAM, SOUTH
OF HANOI, AROUND TAU 60. DYNAMIC MODEL GUIDANCE IS IN STRONG
AGREEMENT LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK
FORECAST.
   C. PRIOR TO TAU 72, TS 21W WILL REMAIN OVER LAND AND CONTINUE TO
TRACK TO THE WEST-NORTHWEST UNDER THE INFLUENCE OF A STR LOCATED
OVER CENTRAL CHINA. THE SYSTEM IS FORECAST TO REMAIN OVER LAND AND
RAPIDLY WEAKEN, COMPLETELY DISSIPATING BY TAU 96 DUE TO INTERACTION
WITH THE RUGGED TERRAIN OF SOUTHEAST ASIA. DYNAMIC MODEL GUIDANCE IS
IN GOOD OVERALL GENERAL AGREEMENT, LENDING HIGH CONFIDENCE IN THIS
PORTION OF THE JTWC TRACK FORECAST.//
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