WDPN31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 
024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.1N 111.7E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 206 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 31 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN 
ASYMMETRIC CORE OF CONVECTION DUE TO THE PERSISTENT HIGH VERTICAL
WIND SHEAR, WITH WARMING CLOUD TOP TEMPERATURES. A 260304Z COWVR
COLOR 34GHZ MICROWAVE IMAGE REVEALS CONVECTIVE BANDING AROUND THE
WESTERN AND SOUTHERN QUADRANTS, WITH AN OBLONG, DEFINED LOW-LEVEL
CIRCULATION CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH MEDIUM
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS, CONSISTENT 
WITH THE DEGRADED CONVECTIVE STRUCTURE, IS BASED ON THE LOWER END OF 
THE AGENCY DVORAK ESTIMATES AND RECENT CIMSS ADT, AIDT OBJECTIVE 
ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   CIMSS SATCON: 72 KTS AT 260322Z
   CIMSS ADT: 55 KTS AT 260600Z
   CIMSS AIDT: 55 KTS AT 260600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND 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: TROPICAL STORM (TS) 22W WILL CONTINUE TRACKING
WESTWARD THROUGH TAU 24 ALONG THE SOUTHERN PERIPHERY OF THE STR TO
THE NORTH. THE SYSTEM WILL WEAKEN STEADILY DUE TO PERSISTENT HIGH
(25-30 KNOTS) VERTICAL WIND SHEAR. AFTER TAU 24, THE STR WILL WEAKEN 
AS UPPER-LEVEL WESTERLIES SHIFT INTO SOUTHERN CHINA WEAKENING THE STR 
TO THE NORTH WHILE ANOTHER STR OVER THE BAY OF BENGAL EFFECTIVELY 
BLOCKS ANY FURTHER WESTWARD PROGRESSION. CONSEQUENTLY, THE SYSTEM WILL 
SLOW SIGNIFICANTLY AND STALL NEAR THE COAST OF CENTRAL VIETNAM, WHICH 
WILL RESULT IN FURTHER WEAKENING DUE TO FRICTIONAL EFFECTS. AFTER TAU 
48, TS 22W WILL TRACK EASTWARD ALONG THE NORTHERN PERIPHERY OF A BELT 
OF LOW-LEVEL WESTERLIES THAT FEED INTO THE APPROACHING TROPICAL 
CYCLONE (23W), WITH STEADY DEVELOPMENT AND POSSIBLE DISSIPATION BY TAU 
120.      

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN GOOD 
AGREEMENT ONLY THROUGH TAU 24, WITH INCREASING HIGH UNCERTAINTY AFTER 
TAU 24 AS THE SYSTEM WEAKENS AND THE PRIMARY STEERING INFLUENCE TO THE 
NORTH WEAKENS. PROBABILISTIC GUIDANCE REVEALS A SIMILAR DEGREE OF 
UNCERTAINTY BUT ALSO CONFIRMS THE RAPID WEAKENING OF THE SYSTEM 
THROUGH THE FORECAST PERIOD.   

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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