WDPN31 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (LIONROCK) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.0N 110.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 276 NM EAST-SOUTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND RADAR
IMAGERY DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION (LLC) WITH 
IMPROVED CONVECTIVE BANDING. A 081111Z SSMIS 91GHZ COLOR COMPOSITE 
IMAGE ALSO INDICATES IMPROVED CONVECTIVE STRUCTURE WITH THE LLC
POSITIONED ALONG EASTERN HAINAN ISLAND. SURFACE OBSERVATIONS OVER
HAINAN ISLAND ARE RELATIVELY WEAK WITH A MINIMUM SLP OF 994MB NEAR
THE CENTER. OVERALL, THERE IS HIGH CONFIDENCE IN THE INITIAL
POSITION BASED ON THE EIR AND RADAR IMAGERY. THERE IS HIGH 
CONFIDENCE IN THE INITIAL INTENSITY BASED ON AN AVERAGE OF THE RJTD 
DVORAK INTENSITY ESTIMATE AND THE LATEST ADT AND CIMSS SATCON 
ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH STRONG 
POLEWARD AND EQUATORWARD OUTFLOW, LOW VERTICAL WIND SHEAR AND WARM 
SST (28C).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: TS 22W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE POSITIONED TO
THE NORTH AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 081112Z
   CIMSS ADT: 47 KTS AT 081130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: INTERACTION WITH LAND

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: TS 22W IS EXPECTED TO CONTINUE TRACKING SLOWLY
NORTHWESTWARD TO NORTH-NORTHWESTWARD THROUGH TAU 24 AS IT TRACKS
OVER HAINAN ISLAND. AFTER TAU 12, SLIGHT WEAKENING BACK TO 35 KNOTS 
WILL OCCUR. AFTER TAU 24, THE SYSTEM WILL TURN WEST-NORTHWESTWARD TO 
WESTWARD THROUGH TAU 48 WITH A SLIGHT RE-INTENSIFICATION TO 40 
KNOTS. HOWEVER, INCREASING VERTICAL WIND SHEAR OVER THE GULF OF 
TONKIN SHOULD HAMPER SIGNIFICANT DEVELOPMENT. AFTER TAU 48, TS 22W 
WILL TRACK WEST-SOUTHWESTWARD AS IT TRACKS INTO NORTHERN VIETNAM AND 
LAOS WITH DISSIPATION EXPECTED NEAR TAU 72.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 WITH A 70NM SPREAD IN SOLUTIONS AT TAU 36 BUT
DIVERGE AFTER TAU 36 WITH INCREASED UNCERTAINTY LENDING MEDIUM
CONFIDENCE TO THE JTWC FORECAST TRACK. THE JTWC FORECAST TRACK IS
POSITIONED NEAR THE MULTI-MODEL CONSENSUS (CONW). INTENSITY
GUIDANCE INDICATES A PEAK RANGING FROM 35 TO 45 KNOTS AT TAU 12
WITH STEADY WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD.

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