Tropical Storm HAISHEN Advisory Sun Apr 05

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (HAISHEN) WARNING
NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 05W (HAISHEN), LOCATED APPROXIMATELY 115 NM
NORTHWEST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 02 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR SATELLITE IMAGERY
CONTINUES TO REVEAL A SLIGHTLY EXPOSED LOW LEVEL CIRCULATION CENTER
THAT HAS BARELY MOVED OVER THE PAST 6 HOURS. THIS IS CONFIRMED BY A
051047 METOP-A MICROWAVE IMAGE WITH GOOD CONFIDENCE. UPPER-LEVEL
ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH HIGH (30 TO 40
KNOT) SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) AND SOME POLEWARD
OUTFLOW. TS 05W IS CURRENTLY QUASI-STATIONARY UNDER A COMPLEX
STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THE STEERING ENVIRONMENT FOR TS HAISHEN WILL REMAIN COMPLEX
OVER ITS LIFECYCLE. THE STR TO THE NORTHWEST WILL CONTINUE TO BUILD
AND PREVENT THE SYSTEM FROM SIGNIFICANT WESTWARD MOVEMENT BEYOND TAU
24. ADDITIONALLY, A NEAR EQUATORIAL RIDGE BUILDING TO THE SOUTHEAST
WILL TRY TO FORCE THE SYSTEM TO THE EAST-NORTHEAST. FINALLY, A DEEP
MID-LATITUDE TROUGH TO THE NORTHEAST FURTHER COMPLICATES THE
STEERING ENVIRONMENT, PREVENTING ANY TRUE POLEWARD MOTION. AS SUCH,
TS 05W IS EXPECTED TO REMAIN IN A VERY SLOW NORTHWESTWARD OR QUASI-
STATIONARY MOTION. INCREASING VWS THROUGH THE FORECAST PERIOD WILL
ERODE THE SYSTEM WITH COMPLETE DISSIPATION BY TAU 48. A WIDE SPREAD
IN THE DYNAMIC MODEL GUIDANCE DUE TO THE COMPLEXITY OF THE STEERING
MECHANICS LEAD TO AN OVERALL LOW CONFIDENCE IN THE JTWC FORECAST
TRACK.//
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