WDPN33 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 033//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 02W (SURIGAE), LOCATED APPROXIMATELY 337 NM NORTHEAST OF 
MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE PAST 
SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) IMAGERY INDICATES THAT 
SURIGAE CONTINUES TO SLOWLY WEAKEN, WITH CLOUD TOPS CONTINUING TO 
WARM AND THE WESTERN SIDE OF THE CONVECTIVE MASS SHOWING SIGNS OF 
SOME MID-LEVEL WESTERLY PRESSURE. ADDITIONALLY, THOUGH THE LARGE EYE 
REMAINS INTACT, THE WIDTH OF THE CONVECTIVE BAND HAS BECOME VERY 
THIN ON THE WESTERN SIDE, HINTING AT THE PRESENCE OF MID-LEVEL DRIER 
AIR AND STRONGER WESTERLY WINDS AT THE 500MB LEVEL. THE INITIAL 
POSITION IS SET WITH HIGH CONFIDENCE BASED ON THE WELL DEFINED EYE 
IN THE MSI AND AN EXTRAPOLATION OF A WELL DEFINED MIC EYE EVIDENT IN 
A 211036Z SSMIS 91GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY 
CONTINUES TO FALL, NOW ASSESSED AT 110 KNOTS, BASED ON AN AVERAGE OF 
MUTLI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES BETWEEN T5.5 AND 
T6.0, AND AN ADT ESTIMATE OF T5.4. THE SYSTEM IS TRACKING SLOWLY 
NORTHWARD, AND IS IN THE PROCESS OF ROUNDING THE AXIS OF THE 
SUBTROPICAL RIDGE (STR) TO THE EAST. ENVIRONMENTAL CONDITIONS REMAIN 
GENERALLY FAVORABLE, THOUGH BECOMING INCREASINGLY MARGINAL. SHEAR 
REMAINS LOW (8-10 KTS), AND THE UPPER-LEVEL OUTFLOW REMAINS STRONG, 
PARTICULAR TO POLEWARD. AS THE SYSTEM HAS SLOWED DOWN AS IT 
APPROACHES THE RIDGE AXIS, IT HAS MOVED OVER ITS OWN WAKE, RESULTING 
IN RELATIVELY COOLER SST VALUES NEAR 26C.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY 
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY SURIGAE WILL ROUND THE STR AXIS BY TAU 12 AND BEGIN 
ACCELERATING TOWARDS THE EAST-NORTHEAST ALONG THE NORTHWESTERN 
PERIPHERY OF THE STR TO THE SOUTHEAST. BY TAU 48, THE STR WILL 
WEAKEN AND REPOSITION TO THE SOUTHEAST WHILE A MAJOR SHORTWAVE 
TROUGH DIVES SOUTHWARD OUT OF THE SEA OF JAPAN, LEADING TO A EAST-
SOUTHEASTWARD TRACK THROUGH TAU 72. CONTINUED SLOW WEAKENING IS 
EXPECTED OVER THE NEXT 12-24 HOURS, PRIMARILY IN RESPONSE TO THE 
PERSISTENT MID-LEVEL DRY AIR AND THE IMPACT OF COOLER SSTS. BY TAU 
36, A MAJOR SHORTWAVE TROUGH CURRENTLY OVER EASTERN CHINA WILL 
RAPIDLY MOVE OVER TY SURIGAE, AND IMPARTING RAPIDLY INCREASING 
WESTERLY SHEAR (30-35 KTS) AND CONVERGENT FLOW ALOFT, GENERATE A 
STEADY AND RAPID WEAKENING TREND THROUGH TAU 72. BY TAU 72 THE 
TROUGH IS EXPECTED TO HAVE MOVED PAST SURIGAE, LEAVING BEHIND A MUCH 
WEAKER SYSTEM, MOVING EASTWARD ALONG THE MID-LEVEL WESTERLY GRADIENT 
FLOW. DYNAMIC MODEL SOLUTIONS ARE IN GOOD AGREEMENT THOUGH TAU 48, 
BUT DIVERGE THEREAFTER, AS MODELS DEPICT VARYING DEGREES OF 
INTERACTION BETWEEN THE SHORTWAVE AND TY SURIGAE. THE GFS, AND GFS 
ENSEMBLE DEPICT LESS INTERACTION WITH THE TROUGH AND HAVE COME INTO 
BETTER AGREEMENT WITH THE REMAINDER OF THE CONSENSUS MEMBERS SINCE 
THE LAST RUN, BUT REMAIN ON THE SOUTHERN EDGE OF THE ENVELOPE. THE 
REMAINDER OF THE CONSENSUS MEMBERS SHOW MORE INTERACTION AND KEEP 
THE SYSTEM MOVING MORE EASTWARD THROUGH TAU 72. THE CURRENT FORECAST 
TRACK THROUGH TAU 72 LIES JUST NORTH AND SLIGHTLY FASTER THAN THE 
CONSENSUS MEAN WITH MODERATE CONFIDENCE.
   C. BEYOND TAU 72, THE FORECAST BECOMES HIGHLY UNCERTAIN, WITH TWO 
DISTINCT SCENARIOS EMERGING. THE GENERAL PATTERN INDICATES A SECOND 
MAJOR SHORTWAVE TROUGH DIVING SOUTHWARDS OUT OF THE SEA OF JAPAN BY 
TAU 84. THE DIVERGENCE IN SCENARIOS IS BASED ON THE VARIANCE IN 
RELATIVE POSITIONING BETWEEN THE TROUGH AND SURIGAE. THE FIRST 
SCENARIO IS REPRESENTED BY THE GFS AND GFS ENSEMBLE, AND SHOWS THE 
SHEAR ASSOCIATED WITH THE TROUGH DECAPITATING THE TY SURIGAE AND 
LEAVING THE SUBTROPICAL REMNANTS SLOWLY DRIFTING EASTWARD TO THE 
SOUTH OF A TRANSIENT HIGH PRESSURE SYSTEM. THE SECOND SCENARIO 
REPRESENTED BY THE REMAINDER OF THE CONSENSUS MEMBERS SHOWS SURIGAE 
CAPTURED BY THE SHORTWAVE TROUGH AND AN EXTRATROPICAL TRANSITION 
(ETT) AS THE SYSTEM RAPIDLY TRANSLATES NORTHEASTWARD UNDER THE MID-
LATITUDE WESTERLIES. THE CURRENT FORECAST REMAINS CONSISTENT WITH 
THE ETT SCENARIO OVERALL. THE AVAILABLE GUIDANCE SHOWS A VERY LARGE 
SPREAD IN ALONG TRACK UNCERTAINTY, UP TO 1150NM BY TAU 120. SURIGAE 
IS FORECAST TO STEADILY WEAKEN THROUGH TAU 120 AS HIGH SHEAR AND 
MARGINAL SSTS OFFSET THE ROBUST OUTFLOW INTO THE MID- LATITUDE 
WESTERLIES. THE TRACK AND INTENSITY FORECAST REMAINS HIGHLY 
DEPENDENT ON THE DETAILS OF THE SECOND TROUGH AND ITS INTERACTION 
WITH SURIGAE AND THUS BOTH TRACK AND INTENSITY FORECASTS BEYOND TAU 
72 ARE HIGHLY UNCERTAIN.//
NNNN