WDPN31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (KOTO) WARNING NR 
020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5N 112.0E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 262 NM SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 33W (KOTO) WITH CURVED CONVECTIVE BANDING WRAPPING AROUND THE
WESTERN PERIPHERY AND DEEP CONVECTION BUILDING OVER THE CENTER.
CLOUD TOPS NEAR THE CENTER HAS COOLED OVER THE PAST 6 HOURS AND ARE
NOW MEASURING COLDER THAN -80 C IN MULTIPLE AREAS. ENVIRONMENTAL
ANALYSIS INDICATES THAT 33W IS IN A MARGINALLY FAVORABLE ENVIRONMENT 
CHARACTERIZED BY MODERATE POLEWARD OUTFLOW ALOFT AND LOW (5-10 KTS) 
VERTICAL WIND SHEAR OFFSET BY UPWELLING EFFECTS. THE INITIAL POSITION 
IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR IMAGERY. 
THE INITIAL INTENSITY OF 45 KTS IS ALSO ASSESSED WITH MEDIUM 
CONFIDENCE BASED PRIMARILY ON THE AGENCY DVORAK FIXES BELOW. CIMSS 
OBJECTIVE ESTIMATES ARE SLIGHTLY LOWER, AROUND THE 35-40 KNOT RANGE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WEAK STEERING PATTERN WITH RIDGING TO
BOTH THE EAST AND WEST


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS ADT: 39 KTS AT 291200Z
   CIMSS AIDT: 34 KTS AT 291200Z
   CIMSS D-MINT: 39 KTS AT 291011Z
   CIMSS D-PRINT: 34 KTS AT 291200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: UPWELLING

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: 33W IS FORECAST TO DRIFT GENERALLY NORTHWARD
THROUGH TAU 24 AS RIDGING SLOWLY BUILDS IN TO THE EAST, OVER LUZON.
AFTER TAU 24, THE SYSTEM IS FORECAST TO TURN SLOWLY WESTWARD THROUGH 
TAU 48 AS THE PRIMARY STEERING MECHANISM SWITCHES TO A SUBTROPICAL 
RIDGE POSITIONED TO THE WEST. A SOUTHWESTWARD TRACK, ALONG THE 
SOUTHEASTERN PERIPHERY OF THE SUBTROPICAL RIDGE IS THEN FORECAST 
THROUGH TAU 72 AS THE SYSTEM APPROACHES THE COAST OF VIETNAM. 
LANDFALL IS CURRENTLY FORECAST TO OCCUR BETWEEN TAU 72 AND 96. 33W 
WILL THEN TRACK INLAND, TOWARD EASTERN CAMBODIA THROUGH TAU 96. 
REGARDING INTENSITY, 33W IS FORECAST TO MARGINALLY INTENSIFY OVER THE 
NEXT 24 HOURS AS POLEWARD OUTFLOW SLIGHTLY IMPROVES AND SHEAR REMAINS 
LOW. AFTER TAU 36, SOUTHEASTERLY SHEAR AND DRY AIR ENTRAINMENT BEGIN 
TO INCREASE. AS A RESULT, 33W IS FORECAST TO WEAKEN AS IT APPROACHES 
THE COAST. AFTER LANDFALL, 33W WILL THEN RAPIDLY WEAKEN OVER THE 
RUGGED TERRAIN OF VIETNAM WITH DISSIPATION FORECAST TO OCCUR AROUND 
TAU 96.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN
POOR AGREEMENT. THE GDM ENSEMBLE MEAN AND EC-AIFS CONTINUE TO TRACK
THE VORTEX MUCH FURTHER NORTH THROUGH TAU 72 THAN THE REMAINDER OF
GUIDANCE. ALL OTHER MODELS TURN THE SYSTEM WESTWARD STARTING AROUND
TAU 36. ADDITIONALLY, AFTER TAU 72, THE GDM TURNS THE VORTEX
SHARPLY TO THE SOUTHWEST, KEEPING THE SYSTEM OVER WATER RATHER THAN
TRACKING INLAND. OVERALL, CROSS-TRACK AND ALONG-TRACK SPREAD ARE
BOTH VERY LARGE THROUGHOUT THE FORECAST PERIOD. THE JTWC TRACK
FORECAST IS PLACED CLOSER TO THE ECMWF ENSEMBLE MEAN WITH LOW
CONFIDENCE. INTENSITY GUIDANCE IS SPLIT BETWEEN GFS AND COAMPS-TC
INTENSIFYING THROUGH TAU 36 WHILE HAFS-A AND HWRF WEAKEN THE SYSTEM
FROM TAU 0 ONWARD. THE JTWC INTENSITY FORECAST IS PLACED NEAR THE
MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
NNNN