Tropical Storm HAISHEN Advisory Вс, 05.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (FIVE) WARNING NR
08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 05W (HAISHEN), LOCATED APPROXIMATELY 133 NM
NORTH-NORTHWEST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR (EIR) IMAGERY SHOWS THE
SYSTEM HAS MAINTAINED WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER
(LLCC) THAT HAS BECOME PARTIALLY EXPOSED. THE INITIAL POSITION IS
BASED ON THE EIR LOOP AND EXTRAPOLATED FROM A LLCC FEATURE IN THE
041605Z NPP BT88 MICROWAVE PASS WITH POOR CONFIDENCE. THE INITIAL
INTENSITY OF 45 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK
ESTIMATES FROM ALL AGENCIES. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE (15 TO 20 KNOT)
VERTICAL WIND SHEAR (VWS). TS 05W IS CURRENTLY TRACKING WESTWARD
ALONG THE SOUTHERN PERIPHERY OF A RETREATING EXTENSION OF THE
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THE STEERING STR IS EXPECTED TO BE WEAKENED BY A DEEPENING
MID-LATITUDE TROUGH TO THE NORTHEAST. THIS WILL CAUSE TS 05W TO SLOW
DOWN TO NEAR QUASI-STATIONARY MOTION. CONCURRENTLY, THE VWS IS
EXPECTED TO INCREASE AND GRADUALLY ERODE THE SYSTEM, WITH DISSIPATION
BY TAU 48. THERE REMAINS A SIGNIFICANT VARIATION IN THE DYNAMIC
MODEL GUIDANCE LEADING TO LOW CONFIDENCE IN THE JTWC FORECAST
TRACK.//
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