Tropical Storm HAISHEN Advisory сб, 04.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING
NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (FIVE), LOCATED APPROXIMATELY 136 NM
EAST-NORTHEAST OF CHUUK, FSM, HAS TRACKED WESTWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER WITH
THE BULK OF THE CONVECTION SHEARED TO THE NORTHWEST. THE INITIAL
POSITION IS BASED ON THE EIR LOOP AND RECENT MICROWAVE SATELLITE
PASSES WITH GOOD CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 30
KNOTS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM ALL
REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH 10 TO 20 KNOT VERTICAL WIND
SHEAR (VWS) OFFSET BY GOOD POLEWARD OUTFLOW. TD 05W IS TRACKING
WESTWARD ALONG THE SOUTHERN PERIPHERY OF A WEAK EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THE CYCLONE IS NOW FORECAST TO DISSIPATE SOONER - BY TAU 72,
OTHERWISE, THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 05W WILL CONTINUE TRACKING UNDER THE STEERING INFLUENCE OF
THE STR OVER THE NEXT 36 HOURS. AFTERWARDS, A MID-LATITUDE SHORTWAVE
TROUGH DIGGING IN FROM THE NORTHEAST WILL WEAKEN THE STEERING STR AND
CAUSE A PERIOD OF QUASI-STATIONARY MOTION BEFORE A NEAR EQUATORIAL
RIDGE (NER) TO THE SOUTHEAST WILL ASSUME STEERING BY TAU 48. TD 05W
MAY INTENSIFY TO A PEAK OF 40 KNOTS MAINLY DUE TO THE GOOD OUTFLOW.
HOWEVER, AFTER THE NER ASSUMES STEERING AND NUDGES THE SYSTEM
POLEWARD, THE VWS WILL INCREASE AND ERODE THE SYSTEM TO ITS
DISSIPATION. THERE IS HIGH UNCERTAINTY IN THE STEERING PATTERN AS
REFLECTED IN THE WIDE SPREAD IN THE MODEL GUIDANCE; THEREFORE, THERE
IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST.//
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