Tropical Storm SURIGAE Advisory Mo, 19.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 02W (SURIGAE), LOCATED APPROXIMATELY 308 NM EAST
OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) INDICATES AN EXTREMELY INTENSE INVARIABLY SYMMETRICAL SYSTEM
AND A CENTRAL DENSE OVERCAST (CDO) MAINTAINING WELL-DEFINED
ELONGATED 20NM EYE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE FEATURE IN THE MSI LOOP AND
EXTRAPOLATION FROM AN 182157Z SSMIS 91GHZ IMAGE. THE INITIAL
INTENSITY OF 125KTS IS BASED BETWEEN MULTIPLE AGENCY DVORAK FINAL-T
ESTIMATES OF T6.5/127KTS (PGTW, KNES, RJTD, AND RCTP); AND THE
OBJECTIVE ESTIMATES OF T6.8/135KTS (ADT) AND 144KTS (SATCON), ALL
REFLECTING THE EXCEPTIONALLY INTENSE SYSTEM. ANALYSIS INDICATES A
SLIGHTLY MORE FAVORABLE ENVIRONMENT WITH THE LOW (5-10KTS) VERTICAL
WIND SHEAR (VWS) AND WARM (29-30C) SEA SURFACE TEMPERATURES (SSTS)
IN THE PHILIPPINE SEA. THE IMPROVED RADIAL OUTFLOW IS NOW ENHANCING
SLIGHT DEVELOPMENT AFTER A MIDLATITUDE TROUGH MIGRATED TO THE
NORTHEAST AS SURIGAE TRACKS SLOWLY ALONG THE WESTERN PERIPHERY OF
THE SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 02W IS CONTINUING TO TRACK NORTH-NORTHWEST IN A WEAK
STEERING ENVIRONMENT AS THE STR ELONGATES MERIDIONALLY THROUGH TAU
36 AND 48. THE ALONG TRACK ERROR INCREASES AS IT MOVES NEAR A COL
REGION TO THE NORTH AND THEN ROUNDS THE APEX OF THE STR AXIS BY TAU
72. HIGHER VWS, SLIGHTLY COOLER SSTS, AND DIMINISHING OUTFLOW ALOFT
WILL BE THE PRIMARY CAUSE TO GRADUAL WEAKENING, DOWN TO 90KTS BY TAU
72. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A GRADUAL, AND EVEN
CROSS-TRACK SPREAD TO 122NM BY TAU 72. THE GFS ENSEMBLE REMAINS THE
FAR RIGHT OUTLIER, LENDING FAIR CONFIDENCE IN THIS PORTION OF THE
JTWC FORECAST TRACK, WHICH IS LAID CLOSE TO AND SLIGHTLY LEFT OF THE
MULTI-MODEL CONSENSUS.
   C. AFTER TAU 72, TY SURIGAE WILL CREST THE AXIS OF THE STR AND
ACCELERATE NORTHEASTWARD. ONCE SURIGAE MOVES TOWARD THE HIGHER
LATITUDES, IT WILL UNDERGO EXTRATROPICAL TRANSITION AS VWS INCREASES
TO +30KTS, SSTS DECREASE TO 24-25C, WHICH WILL ULTIMATELY LEAD TO A
DECREASE OF INTENSITY TO 75KTS BY TAU 96. THE NUMERICAL MODELS
REMAIN FAIRLY TIGHT IN AGREEMENT AND ONLY SPREAD TO 134NM BY TAU 96,
LENDING FAIR CONFIDENCE DURING THIS TIME. HOWEVER, BEYOND TAU 96
ALONG TRACK / CROSS TRACK ERRORS START INCREASING WITH A GREATER
SPREAD TO 222NM AS THE SYSTEM CONTINUES EXTRATROPICAL TRANSITION,
LENDING LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK
FORECAST.//
NNNN
NNNN