WDPN31 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (BUALOI) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.8N 112.1E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 220 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PERSISTENT CONVECTIVE BANDING BEGINNING TO TIGHTLY WRAP INTO A LOW-
LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH TYPHOON (TY) 26W
(BUALOI). RAPID DEVELOPMENT REMAINS HINDERED BY SLIGHT PRESSURE AND
DRY AIR IMPACTING THE NORTHERN SEMICIRCLE OF THE CIRCULATION. 
HOWEVER, CONVECTIVE ACTIVITY, WITH ASSOCIATED COLD CLOUD TOPS 
CONTINUE TO DEVELOP, UTILIZING FAVORABLE ATMOSPHERIC ENVIRONMENT 
CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM (28-
29 C) SEA SURFACE TEMPERATURES (SST) AND STRONG EQUATORWARD OUTFLOW 
CHANNEL. THE INITIAL POSITION IS ESTIMATED WITH MEDIUM CONFIDENCE 
BASED ON EXTRAPOLATION FROM A 271052Z GPM GMI 89 GHZ MICROWAVE IMAGE. 
THE INITIAL INTENSITY OF 75 KTS IS ALSO ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON DVORAK ESTIMATES OSCILLATING AROUND T4.5.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T5.0 - 90 KTS
   CIMSS ADT: 61 KTS AT 271300Z
   CIMSS AIDT: 66 KTS AT 271300Z
   CIMSS D-MINT: 56 KTS AT 271048Z
   CIMSS D-PRINT: 59 KTS AT 271200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG 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: TY 26W IS EXPECTED TO CONTINUE ITS
NORTHWESTWARD TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A STR TO
THE NORTHEAST. THE ENVIRONMENT IS FORECAST TO REMAIN CONDUCIVE
THROUGHOUT LANDFALL OVER NORTHERN VIETNAM, WITH THE SYSTEM EXPECTED
TO REACH A PEAK INTENSITY OF APPROXIMATELY 95 KTS AROUND TAU 24.
WITHIN THE NEXT 12 HOURS, NUMERICAL MODEL GUIDANCE INDICATES THAT
TY 26W WILL OVERCOME THE DRY AIR INTRUSION FROM THE NORTH. SHORTLY
AFTER, THE SYSTEM IS EXPECTED TO MAKE LANDFALL AND BEGIN WEAKENING
FROM AN IMPRESSIVE 65 KTS AROUND TAU 36. FRICTIONAL EFFECTS OF LAND
INTERACTION, COMBINED WITH MOUNTAINOUS TERRAIN, WILL RESULT IN
DISSIPATION, WHICH IS EXPECTED TO OCCUR BETWEEN TAUS 48 AND 72.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS GENERALLY IN
GOOD AGREEMENT. JGSM, WHICH REMAINS AN OUTLIER, PREDICTS A
TRACK SLIGHTLY CLOSER TO HAINAN. HOWEVER, OVERALL GUIDANCE AGREEMENT 
HAS IMPROVED SINCE LAST FORECAST, WITH 65 NM CROSS-TRACK SPREAD AT 
LANDFALL. JTWC TRACK FORECAST IS THEREFORE PLACED WITH HIGH 
CONFIDENCE AND CLOSE TO THE MULTI-MODEL CONSENSUS. WITH RESPECT TO 
INTENSITY, ALMOST ALL AVAILABLE GUIDANCE MODELS PREDICT AN INCREASE 
IN MAXIMUM WIND SPEEDS OVER THE NEXT 24 HOURS. MULTIPLE RAPID 
INTENSIFICATION (RI) AIDS HAVE BEEN TRIGGERED, PROJECTING PEAK WINDS 
TO REACH 100-115 KTS. THE JTWC OFFICIAL FORECAST REMAINS MORE 
CONSERVATIVE AND IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS, WITH 
INTENSITY VALUES PARALLEL TO HAFS-A GUIDANCE THROUGHOUT THE FORECAST 
PERIOD.

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