WDPN31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI)        
WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2N 123.3E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 164 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS CONTINUE TO HINDER
THE DEVELOPMENT OF TROPICAL STORM (TS) 22W. UPPER-LEVEL ANALYSIS
DEPICTS A POINT SOURCE EAST OF THE SYSTEM CENTER, WHICH IS PRODUCING 
VIGOROUS WESTWARD OUTFLOW AND PERSISTENT DEEP CONVECTION OVER THE 
WESTERN QUADRANT. HOWEVER, A BROAD UPPER-LEVEL TROUGH OVER THE 
NORTHERN SEMICIRCLE AND THE ASSOCIATED CONVERGENCE IS SUPPRESSING 
CONVECTIVE DEVELOPMENT. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) 
REVEALS DEEP CONVECTION BUILDING OVER THE SOUTHWESTERN QUADRANT OF A 
BROAD, PARTIALLY EXPOSED LOW-LEVEL CIRCULATION (LLC). A 230450Z AMSR2 
37GHZ COLOR MICROWAVE IMAGE SUPPORTS THE INITIAL POSITION WITH HIGH 
CONFIDENCE AND SHOWS CONVECTIVE BANDING WRAPPING TIGHTLY INTO A RAGGED 
BUT WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. THE INITIAL INTENSITY 
OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON CONCURRENT DVORAK 
CURRENT INTENSITY ESTIMATES OF 3.0 (45 KNOTS) FROM ALL AGENCIES AS 
WELL AS THE 230700Z DPRINT ESTIMATE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS ADT: 32 KTS AT 230600Z
   CIMSS AIDT: 33 KTS AT 230600Z
   CIMSS DPRINT: 45 KTS AT 230700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM (TS) 22W IS FORECAST TO TRACK
WEST-NORTHWESTWARD THROUGH TAU 12 ALONG THE SOUTHWESTERN PERIPHERY
OF THE STR, TOWARD A BREAK IN THE STR PRODUCED BY A MIDLATITUDE
SHORTWAVE TROUGH DIGGING INTO THE EAST CHINA SEA. AFTER TAU 12, THE
STR WILL REBUILD TO THE NORTH TURNING THE SYSTEM ONTO A MORE
WESTWARD TRAJECTORY. THE SYSTEM WILL MAKE LANDFALL NEAR TAU 06,
WITH SIGNIFICANT WEAKENING COMMENCING. AFTER TAU 12, TS 22W WILL
WEAKEN AND DECOUPLE WHILE CROSSING THE RUGGED TERRAIN OF LUZON,
WITH A LIKELY LEESIDE JUMP. THIS WILL RESULT IN AN APPARENT DIP IN
THE FORECAST TRACK AS A NEW PRESSURE CENTER FORMS AND STRENGTHENS
OFF THE WEST COAST OF LUZON NEAR TAU 24. AFTER TAU 36, THE SYSTEM
WILL RESUME A WESTWARD TRACK UNDER THE STR TO THE NORTH WITH STEADY
INTENSIFICATION TO ABOUT 60 KNOTS BY TAU 72. AFTER TAU 72, TS 22W
WILL SLOW AND STALL AS A SUBTROPICAL RIDGE BUILDS TO THE WEST OF
THE SYSTEM INDUCED BY THE DEVELOPING TROPICAL CYCLONE IN THE BAY OF
BENGAL (TC 03B).      

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 72, WITH A 60NM TO 70NM CROSS-TRACK SPREAD
FROM TAU 48 TO TAU 72. AFTER TAU 72, THE GUIDANCE DIVERGES
SIGNIFICANTLY WITH MANY MODELS INDICATING A QUASISTATIONARY TRACK
MOTION AND STALL EAST OF VIETNAM. GFS REMAINS THE SOLE OUTLIER WITH
A DISSIPATION TRACK INTO CENTRAL VIETNAM. THE 221800Z ECMWF
ENSEMBLE (EPS) AND THE 230000Z GFS ENSEMBLE (GEFS) SHOW THE LARGE
MAJORITY OF SOLUTIONS STALLING EAST OF VIETNAM WHILE MAINTAINING A
MINIMAL TROPICAL STORM STRENGTH SYSTEM. RELIABLE INTENSITY GUIDANCE
SHOWS A PEAK INTENSITY NEAR TAU 72 RANGING FROM 52 KNOTS (HAFS-A)
TO AS HIGH AS 76 KNOTS (HWRF). THE JTWC INTENSITY FORECAST REMAINS
HIGHLY CONSISTENT WITH PREVIOUS WARNINGS SHOWING A PEAK INTENSITY
OF 60 KNOTS, HEDGED JUST HIGHER THAN THE INTENSITY CONSENSUS (ICNW)
PEAK OF 52 KNOTS. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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