WDPN33 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (ELEVEN) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.9N 119.6E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 214 NM NORTH-NORTHWEST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 11W IS LOCATED ALONG THE WESTERN PERIPHERY
OF A LARGE, APPROXIMATELY 650NM DIAMETER LOW PRESSURE AREA, WHICH
IS FORECAST TO GRADUALLY DEEPEN AND STRENGTHEN INTO A MONSOON 
DEPRESSION AS IT TRACKS POLEWARD OVER THE NEXT FEW DAYS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS RADIAL DEEP
CONVECTION BUILDING OVER AN OBSCURED LOW-LEVEL CIRCULATION CENTER
(LLCC). ANIMATED EIR CONFIRMS THE COOLING CLOUD TOPS OF THE CENTRAL
DENSE OVERCAST CONVECTIVE MASS, SUPPORTING THE RATE OF
INTENSIFICATION OF TROPICAL STORM (TS) 11W. WATER VAPOR IMAGERY
REVEALS ENHANCED FAVORABLE DUAL-CHANNEL OUTFLOW. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
AFOREMENTIONED ANIMATED MSI. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: BETWEEN A WEAK DEEP-LAYER RIDGE TO THE
SOUTHWEST AND A LARGE LOW PRESSURE AREA EAST OF LUZON.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 230530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 11W IS FORECAST TO TRACK SOUTHWESTWARD OVER
THE NEXT 12 HOURS BEFORE SHARPLY CURVING IN A CYCLONIC DIRECTION
FROM TAU 12-36, PASSING OVER NORTHERN LUZON. AFTER TAU 36, THE
SYSTEM WILL TRACK AS THE SYSTEM BECOMES ENGULFED IN THE LARGER
ENHANCED CYCLONIC FLOW, AND ULTIMATELY DISSIPATE INTO A DEVELOPING
MONSOON DEPRESSION BY THE END OF THE FORECAST PERIOD. STRONG 
UPPER-LEVEL DIFFLUENCE, LOW VERTICAL WIND SHEAR, AND WARM SEA
SURFACE TEMPERATURES ALLOW FOR STRONG INTENSIFICATION TO A PEAK OF
60KTS AT TAU 36. TOPOGRAPHIC INTERACTION WITH THE MOUNTAINOUS
TERRAIN OF NORTHERN LUZON WILL RESULT IN INITIATE WEAKENING AS TS
10W ABSORBS INTO THE BROADER FLOW. 

MODEL DISCUSSION: THE COMPLEX STEERING ENVIRONMENT IS HIGHLIGHTED
IN THE IRREGULAR CYCLONIC TRACK MOTION APPARENT IN THE JTWC
MULTI-MODEL CONSENSUS. IN THE LATE-TERM FORECAST, THERE IS A SPREAD
OF 225NM, RESULTING FROM THE UNCERTAINTY AS THE SYSTEM DISSIPATES
INTO THE VORTICITY FIELD. THE INTENSITY GUIDANCE IS IN GOOD
AGREEMENT THAT SIGNIFICANT INTENSIFICATION WILL OCCUR WITHIN THE
FIRST 24-36 HOURS OF THE FORECAST TO PEAKS BETWEEN 45-65KTS.
SEVERAL RAPID INTENSIFICATION AIDS INDICATE HIGH POTENTIAL FOR
RAPID INTENSIFICATION AS WELL. 

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