Tropical Storm SURIGAE Advisory 4月15日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SURIGAE) WARNING
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TROPICAL STORM (TS) 02W (SURIGAE), LOCATED APPROXIMATELY 85 NM
WEST-SOUTHWEST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 03 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS FORMATIVE BANDING WRAPPING INTO A LOW LEVEL
CIRCULATION WITH DENSE, FLARING CONVECTION OVERHEAD. THE INITIAL
POSITION IS BASED ON A 141616Z AMSR2 36GHZ IMAGE WHICH DEPICTS BROAD
BANDING WRAPPING INTO A LOW LEVEL CIRCULATION CENTER. THE INITIAL
INTENSITY OF 45 KTS IS BASED ON THE DVORAK INTENSITY ESTIMATES OF
T3.0/45KTS FROM PGTW AND RJTD AND THE OBJECTIVE ADT OF T2.8/41KTS.
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH ROBUST DUAL OUTFLOW,
LOW TO MODERATE (10-20KT) VERTICAL WIND SHEAR (VWS), AND VERY WARM
(29-30C) SEA SURFACE TEMPERATURE (SST) IN THE PHILIPPINE SEA. TS 02W
IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY OF AN EXTENSION
OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 02W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD UNDER THE STR
AND WILL CONTINUE TO STEADILY INTENSIFY AS IT CONTINUES TO
CONSOLIDATE WITHIN A FAVORABLE ENVIRONMENT, REACHING 95 KTS BY TAU
72. THERE IS SOME UNCERTAINTY IN INTENSIFICATION BETWEEN TAU 36 AND
TAU 72 DUE TO THE CONSISTENT SHEAR AND PRESSURE ON THE EASTERN SIDE
OF TS 02W. NUMERICAL MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH A
CROSS-TRACK SPREAD OF 160NM BY TAU 72 LENDING TO HIGH CONFIDENCE IN
THE EARLY PORTION OF THE JTWC TRACK FORECAST WHICH IS IN LINE WITH
THE CURRENT MODEL CONSENSUS.
   C. AFTER TAU 72, A MIDLATITUDE TROUGH NORTH OF THE STR WILL BEGIN
TO DEEPEN, CAUSING A BREAK IN STR. ONCE THE STR BREAKS, TS SURIGAE
WILL  BEGIN TO TURN POLEWARD, TRACKING AROUND EASTERN PORTION OF THE
RIDGE. THE FAVORABLE ENVIRONMENT WILL CONTINUE AND BRING TS 02W TO A
PEAK OF 115KTS AT TAU 96 AND WEAKENING SLIGHTLY AFTERWARDS AS COOLER
SST PREVAIL.  NUMERICAL MODEL CROSS-TRACK SPREAD HAS DECREASED TO
270NM AT TAU 120 OVER THE PAST SIX HOURS, LENDING FAIR CONFIDENCE IN
THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.//
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