WDPN31 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (BUALOI) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.7N 107.1E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 123 NM NORTHWEST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTIVE SPIRAL BANDS WRAPPING INTO A VERY RAGGED AND INCOMPLETE
CLOUD-FREE LOW-LEVEL CIRCULATION CENTER (LLCC), INDICATING THE
SYSTEM STRUGGLING TO DEVELOP CONSISTENT AND STRUCTURALLY
SYMMETRICAL EYEWALL. THE INITIAL POSITION HAS BEEN LOCATED WITH
HIGH CONFIDENCE, SUPPORTED BY RADAR DATA, AGENCY FIXES, AND A
MICROWAVE EYE SEEN IN A 281043Z WSFM MWI COLOR 37 GHZ IMAGE. THE
INITIAL INTENSITY OF 70 KTS HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE,  
BASED ON CONSISTENT DVORAK FIXES LISTED BELOW. OBJECTIVE INTENSITY 
AIDS STILL OFFER RATHER LARGE GUIDANCE SPREAD OF 57 TO 79 KTS, ADDING 
SOME UNCERTAINTY TO THE INTENSITY EVALUATION. AS THE SYSTEM NEARS 
LANDFALL, ENVIRONMENTAL CONDITIONS REMAIN MARGINALLY FAVORABLE, WITH 
LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM (28-29 C) SEA SURFACE 
TEMPERATURES (SST), AND MODERATE EQUATORWARD OUTFLOW. HOWEVER, AS THE 
SYSTEM APPROACHES THE COASTLINE, LAND INTERACTION WITH THE WIND FIELD 
IS CERTAINLY HALTING FURTHER INTENSIFICATION.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED EAST
OF TAIWAN, EXTENDING SOUTH, TOWARD THE PHILIPPINES

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS ADT: 57 KTS AT 281130Z
   CIMSS AIDT: 62 KTS AT 281130Z
   CIMSS D-PRINT: 75 KTS AT 281200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: FRICTIONAL EFFECTS OF LAND INTERACTION

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
STEERING RIDGE. LANDFALL IS EXPECTED TO OCCUR WITHIN THE NEXT FEW
HOURS. BY TAU 12, TY 26W IS FORECAST TO WEAKEN TO 50 KTS, DUE TO
FRICTIONAL EFFECTS ASSOCIATED WITH LAND INTERACTION, WITH WEAKENING
ACCELERATING AS THE LLCC MOVES OVER THE MOUNTAINOUS TERRAIN INLAND.
FULL DISSIPATION IS EXPECTED SHORTLY AFTER TAU 24.

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGHOUT THE FORECAST PERIOD, RESULTING IN HIGH CONFIDENCE IN THE
OFFICIAL JTWC TRACK PREDICTION. SIMILARLY, INTENSITY ASSESSMENT IS
PLACED WITH HIGH CONFIDENCE, AS ALL MEMBERS OF THE AVAILABLE 
CONSENSUS INDICATE QUICK WEAKENING IMMEDIATELY FOLLOWING THE LANDFALL 
OVER THE
VIETNAMESE COASTLINE.

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