WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 029//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 02W (SURIGAE), LOCATED APPROXIMATELY 305 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 06 KTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY DEPICTS A VERY BROAD, CLEARLY DEFINED 30 NM WIDE EYE. SOME 
EROSION OF THE NORTHEASTERN EYEWALL IS EVIDENT IN THE EIR IMAGERY, 
THOUGH MORE RECENT DATA SUGGESTS THAT IT IS IN FACT REFORMING. THE 
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 30 NM 
EYE AND CLOSE GROUPING OF MULTI-AGENCY POSITION FIXES WITH 
ADDITIONAL SUPPORT FROM EXTRAPOLATING THE FIX POSITION PROVIDED BY A 
200942Z SENTINEL-1B SYNTHETIC APERTURE RADAR (SAR) PASS. THE CURRENT 
INTENSITY HAS BEEN INCREASED TO 120 KTS WITH HIGH CONFIDENCE BASED 
ON  A BLEND OF ESTIMATES FROM MULTIPLE SOURCES INCLUDING; MULTI-
AGENCY DVORAK INTENSITY ESTIMATES BETWEEN T6.0-T6.5, AN ADT ESTIMATE 
OF T6.0, A SATCON ESTIMATE OF 131 KTS, A SMAP PASS FROM 200932Z 
INDICATING WINDS IN THE EASTERN HEMISPHERE OF 120-130 KTS AND THE 
AFOREMENTIONED SAR PASS WHICH INDICATED WINDS OF 120-135 KTS IN THE 
EYEWALL. TY SURIGAE IS MOVING NORTHWARD ALONG THE WESTERN PERIPHERY 
OF A DEEP LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST, AND MOVING 
THROUGH A FAVORABLE ENVIRONMENT WITH LOW (5-10 KTS) VWS AND STRONG 
POLEWARD OUTFLOW. OVER THE LAST 12 HOURS, THE SYSTEM HAS MOVED AWAY 
FROM THE POOL OF COOLER, UPWELLED WATERS, AND THUS IS EXHIBITING AN 
IMPROVED CORE STRUCTURE.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY 
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 24 HOURS TY SURIGAE WILL CONTINUE TRACKING NORTH-
NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF A STR LOCATED FAR TO 
THE EAST. BY TAU 36, SURIGAE WILL ROUND THE NORTHWESTERN PERIPHERY 
OF THE STR AND TURN SHARPLY NORTHEASTWARD. FORWARD SPEED IS FORECAST 
TO INCREASE STEADILY AFTER TAU 36 AS THE SYSTEM SLIDES ALONG THE 
STRENGTHENED GRADIENT BETWEEN THE STR AND AN APPROACHING MID-
LATITUDE SHORTWAVE TROUGH. BY TAU 72, SURIGAE WILL BE TRAVELING NEAR 
DUE EAST AS IT COMES UNDER THE INFLUENCE OF THE AFOREMENTIONED MID-
LATITUDE TROUGH AND STRONG MID-LEVEL WESTERLY FLOW ALOFT. THE JTWC 
FORECAST TRACK REMAINS CONSISTENT WITH THE PREVIOUS FORECAST THROUGH 
TAU 72. NUMERICAL MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT THROUGH 
TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE FORECAST 
TRACK. INTENSITY IS FORECAST TO REMAIN STEADY THOUGH TAU 12, THEN 
BEGIN TO GRADUALLY WEAKEN THROUGH TAU 24. MORE RAPID WEAKENING IS 
FORECAST BETWEEN TAUS 36 AND 72, AS THE SYSTEM MOVES INTO AN 
INCREASINGLY UNFAVORABLE ENVIRONMENT, WITH INCREASING MID-LEVEL 
WESTERLY SHEAR, ENTRAINMENT OF DRIER AIR AND COOLER SSTS. THE JTWC 
INTENSITY FORECAST LIES
   C. IN THE LATER PORTION OF THE FORECAST, TY SURIGAE WILL CONTINUE 
TO ACCELERATE EASTWARD AHEAD OF AN ADVANCING MAJOR SHORTWAVE TROUGH 
AND ALONG THE NORTHERN PERIPHERY OF THE STR TO THE SOUTHEAST. 
NUMERICAL MODEL GUIDANCE SUPPORTS THE GENERAL TRACK FORECAST BUT 
DEPICTS INCREASING UNCERTAINTY IN BOTH CROSS AND ALONG-TRACK MODES 
AFTER TAU 72 AS THE SYSTEM WEAKENS AND MODELS VARY IN THE AMOUNT AND 
STRENGTH OF INTERACTION WITH THE SHORTWAVE TROUGH AND THE RAPIDITY 
OF THE WEAKENING TREND. THE JTWC FORECAST TRACK LIES NEAR THE 
CONSENSUS MEAN, TO THE NORTH AND FASTER THAN THE GFS SOLUTION, WHILE 
SLOWER THAN THE ECMWF SOLUTION. IN LIGHT OF LARGE SPREAD IN THE 
GUIDANCE AND ENSEMBLE MEMBERS, THERE IS OVERALL LOW CONFIDENCE IN 
THIS PORTION OF THE FORECAST TRACK. AS THE SHORTWAVE TROUGH MOVES 
PAST TY SURIGAE, IT WILL IMPART STRONG CONVERGENT WESTERLY FLOW 
ALOFT IN ITS WAKE, INCREASING VWS TO 40-50 KTS OR MORE BY TAU 96. 
THE SYSTEM WILL TRANSIT GENERALLY ALONG THE 26C ISOTHERM, BUT DUE TO 
THE HIGH SHEAR AND THE CONVERGENT WESTERLY FLOW ALOFT, WILL STEADILY 
WEAKEN THROUGH TAU 120. AS TY 02W MOVES EASTWARD ALONG THE 
BAROCLINIC ZONE, IT IS FORECAST TO DEVELOP WEAK TO MODERATE THERMAL 
ADVECTION AND A FRONTAL STRUCTURE BEGINNING EXTRA-TROPICAL 
TRANSITION (ETT) BY TAU 96.//
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