WDPN31 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (BUALOI) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1N 119.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 138 NM SOUTHWEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 26W (BUALOI) WITH A BROAD AREA OF DEEP CONVECTION ENTIRELY
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE LACK OF ANY
RECENT MICROWAVE IMAGERY ON THE SYSTEM HAS CAUSED THE STRUCTURE TO
BE A BIT OF A MYSTERY FOR NOW. CENTRAL CONVECTION HAS CERTAINLY
IMPROVED OVER THE PAST 6 HOURS AS THE VORTEX FURTHER DISTANCES
ITSELF FROM THE PHILIPPINES. ENVIRONMENTAL ANALYSIS INDICATES THAT
26W IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE RADIAL
OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) NORTHEASTERLY VERTICAL
WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. THE
INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ENTIRELY ON
THE ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 60 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF THE SUBTROPICAL
RIDGED POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 57 KTS AT 261200Z
   CIMSS AIDT: 49 KTS AT 261200Z
   CIMSS D-PRINT: 52 KTS AT 261200Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: 26W IS FORECAST TO TRACK WEST-NORTHWESTWARD
ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH TAU
36. AFTER TAU 36, THE TRAJECTORY WILL TURN SLIGHTLY MORE
NORTHWESTWARD AS THE SYSTEM TRACKS ALONG THE SOUTHWESTERN EXTENT OF
THE RIDGE. LANDFALL IS FORECAST TO OCCUR NEAR TAU 48, NORTH OF HUE.
THE ENVIRONMENT IS EXPECTED TO BE CONDUCIVE FOR FURTHER DEVELOPMENT
THROUGHOUT THE SOUTH CHINA SEA WITH LOW VERTICAL WIND SHEAR AND
WARM SEA SURFACE TEMPERATURES. AS A RESULT, 26W IS FORECAST TO
GRADUALLY INTENSIFY TO AROUND 75 KTS BEFORE MAKING LANDFALL IN
VIETNAM. RAPID DETERIORATION WILL THEN OCCUR AS THE REMNANT VORTEX
TRACKS INTO LAOS, WITH DISSIPATION AROUND TAU 72. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH A 100 NM CROSS TRACK SPREAD AND MINIMAL ALONG TRACK 
SPREAD AT TAU 48, NEAR THE TIME OF LANDFALL. AS A RESULT, THE JTWC 
TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH 
CONFIDENCE. INTENSITY GUIDANCE AGREES ON GRADUAL INTENSIFICATION 
THROUGH TAU 48 WITH PEAK INTENSITIES ALL AROUND 70-75 KTS. ALL MODELS 
THEN DEPICT RAPID WEAKENING AFTER TAU 48. THE JTWC INTENSITY FORECAST 
IS PLACED IN LINE WITH THE BULK OF GUIDANCE WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM//
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