WDPN31 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 34W (MAN-YI) WARNING NR 
06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 34W (MAN-YI), LOCATED APPROXIMATELY 553 NM 
SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT 17 
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) INDICATES A QUICKLY CONSOLIDATING AND EXPANDING SYSTEM 
WITH CONVECTIVE BANDING FEATURES BEGINNING TO WRAP COMPLETELY AROUND 
THE LLCC. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED 
ON THE BANDING FEATURES IN THE MSI, SUPPORTED BY AN ANALYSIS OF 
ASCAT AMBIGUITIES FROM 202357Z. THE INITIAL INTENSITY OF 50 KNOTS IS 
BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T3.0 FROM PGTW AND 
KNES, HEDGED SLIGHTLY HIGHER IN VIEW OF A T3.9 (63 KNOTS) AUTOMATED 
DVORAK ESTIMATE, AND A 55 KNOT SATCON ESTIMATE FROM 202056Z. 
OVERALL, THE ENVIRONMENT SURROUNDING MAN-YI IS FAVORABLE FOR 
INTENSIFICATION WITH LOW (10-15 KNOT) VWS, AND WARM
(29-30 CELSIUS) SSTS. THE ONLY HINDRANCE IS THE SINGLE, WESTWARD 
OUTFLOW CHANNEL, PROVIDING MODERATE LEVELS OF UPPER-LEVEL OUTFLOW. 
TS 34W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STR CENTERED 
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE OTHER THAN A REDUCTION IN THE 
PEAK INTENSITY TO 95 KNOTS. 
   B. THROUGH TAU 48, TS 34W WILL CONTINUE TO TRACK NORTHWESTWARD
UNDER THE INFLUENCE OF THE AFOREMENTIONED STR, THOUGH THE TRACK WILL 
BECOME STEADILY MORE NORTHWESTWARD AS THE STR BEGINS TO REORIENT TO 
A MORE SOUTHEAST TO NORTHWEST ORIENTATION. BETWEEN TAUS 48 AND 72, 
THE SYSTEM WILL TURN SHARPLY TOWARDS THE NORTH AS THE STR WEAKENS 
AND MOVES EASTWARD. THE SYSTEM WILL STEADILY INTENSIFY OVER THE NEXT 
36 HOURS UNDER FAVORABLE ENVIRONMENTAL CONDITIONS OF LOW VWS AND 
MODERATE WESTERLY OUTFLOW, REACHING A PEAK INTENSITY OF 95 KNOTS AT 
TAU 36. HOWEVER, AFTER THIS POINT AND THROUGH TAU 72, INCREASING VWS 
WILL LEAD TO A SLOW WEAKENING TREND. MODEL GUIDANCE IS IN STRONG 
AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF 
THE JTWC FORECAST TRACK. 
   C. BEYOND TAU 72, TS MAN-YI WILL BECOME QUASI-STATIONARY AS IT
ENTERS A WEAK STEERING PATTERN IN THE COL AREA BETWEEN THE STR TO 
THE EAST AND A BUILDING STR TO THE WEST IN THE PHILIPPINE SEA. 
BETWEEN TAU 72 AND 96, AS THE SYSTEM ENTERS INTO THE COL REGION, 
THERE WILL BE A SHORT PERIOD OF REINTENSIFICATION AS THE SYSTEM TAPS 
INTO A POLEWARD OUTFLOW CHANNEL AHEAD OF A SHORTWAVE TROUGH PASSING 
TO THE NORTH. BEYOND THIS POINT, INTENSITY WILL DECREASE AGAIN, 
MAINLY DUE TO DRY AIR ENTRAINMENT AS THE SYSTEM INTERACTS WITH A 
COLD DRY AIR MASS SURGING SOUTHWARD. MODEL GUIDANCE IS HIGHLY 
UNCERTAIN AFTER TAU 72, DEPICTING A BIFURCATION SCENARIO. THE AFUM, 
NAVGEM, HWRF AND JGSM MODELS SHOW AN EQUATORWARD LOOP RESULTING IN A 
WESTWARD TRACK AFTER TAU 96, WHILE THE REMAINDER OF THE MODELS 
INCLUDING GFS, ECMWF, COAMPS AND THE CONSENSUS SHOW A SHARP RECURVE 
TO THE NORTHEAST. THE OFFICIAL FORECAST LIES CLOSE TO THE CONSENSUS 
TRACK WITH LOW CONFIDENCE.// 
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