WDIO31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04B (SENYAR) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 3.6N 99.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 894 NM SOUTHWEST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: EASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 8 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RECENT
FLARE-UP OF CENTRAL CONVECTION LINKED TO AN ELONGATED LOW-LEVEL
CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE (TC) 04B (SENYAR). THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON
EXTRAPOLATION FROM A 261510Z METOP-C WIND AMBIGUITIES PRODUCT. THE
INITIAL INTENSITY OF 30 KTS IS ALSO ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A 261512Z METOP-C ASCAT WIND SPEED PRODUCT SHOWING POORLY
ORGANIZED CIRCULATION WITH 30 KT MAXIMUM WINDS, LOCATED
UNDERNEATH STRONG CONVECTION, RESULTING IN LIKELY RAIN
CONTAMINATION. ADDITIONAL ENVIRONMENTAL ANALYSIS REVEALS MARGINAL
ENVIRONMENT WITH WARM (29-30 C) SEA SURFACE TEMPERATURES (SST),
GOOD WESTWARD OUTFLOW, OFFSET BY MODERATE TO HIGH (20-25 KTS)
VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: WEAK INFLUENCE FROM A PREDOMINANTLY
WESTERLY LOW- TO MID-LEVEL FLOW TO THE SOUTHWEST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   CIMSS ADT: 39 KTS AT 261730Z
   CIMSS AIDT: 32 KTS AT 261730Z
   CIMSS D-MINT: 32 KTS AT 261839Z
   CIMSS D-PRINT: 38 KTS AT 261830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC SENYAR IS FORECAST TO TRACK EASTWARD AND
CROSS INTO THE WESTERN PACIFIC AREA OF RESPONSIBILITY WITHIN THE NEXT 
FEW HOURS. SIGNIFICANT LOW-LEVEL CONVERGENCE IS EXPECTED TO RESULT IN
INCREASED CONVECTIVE ACTIVITY, WHILE MARGINAL ENVIRONMENTAL
CONDITIONS LEAVE A WINDOW FOR SLIGHT INTENSIFICATION UP TO 35 KTS. AT 
THE SAME TIME, THE SYSTEM IS EXPECTED TO STRUGGLE WITH CONSOLIDATION 
DUE TO MODERATE TO HIGH VWS, AS WELL AS FRICTIONAL EFFECTS OF LAND 
INTERACTION AS IT APPROACHES THE WESTERN COAST OF MALAYSIA. LANDFALL 
IS EXPECTED NEAR TAU 24, WITH FULL DISSIPATION PRIOR OR AT TAU 36.

MODEL DISCUSSION: AVAILABLE MODEL GUIDANCE, BOTH IN REGARD TO TRACK
AND INTENSITY, IS IN FAIR AGREEMENT AND THEREFORE THE OFFICIAL JTWC
FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE. THE ONLY OUTLIER IN
REGARD TO MAXIMUM WINDS IS COAMPS-TC, WHICH PREDICTS A SIGNIFICANT
INTENSIFICATION (PEAK OF 50-55 KTS) EXTENDING BEYOND TAU 36. IF THE 
SYSTEM MAINTAINS OVER WATER FOR LONGER THAN EXPECTED, INTENSIFICATION 
BEYOND 35 KTS IS POSSIBLE, HOWEVER CONSIDERING THE ENVIRONMENTAL 
PARAMETERS, AS WELL AS LACK OF WELL-DEVELOPED STRUCTURE THAT IS THE 
LESS LIKELY SCENARIO. AVAILABLE TRACK GUIDANCE SHOWS STRONG AGREEMENT 
ON EASTWARD PROPAGATION AND LANDFALL AROUND TAU 24, WHICH WILL RESULT
IN WEAKENING AND EVENTUAL DISSIPATION SHORTLY THEREAFTER.

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