WDPN31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (LIONROCK) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.5N 110.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 310 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 MULTISPECTRAL SATELLITE IMAGERY (MSI) AND RADAR IMAGERY 
DEPICT CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW-LEVEL 
CIRCULATION CENTER (LLCC). A 080624Z AMSR2 89GHZ COLOR COMPOSITE 
IMAGE ALSO INDICATES IMPROVED CONVECTIVE STRUCTURE WITH THE LLCC 
LOCATED JUST UNDER THE EASTERN EDGE OF THE CORE CONVECTION. SURFACE 
OBSERVATIONS OVER HAINAN ISLAND ARE RELATIVELY WEAK WITH THE 
EXCEPTION OF HAIKOU ON THE NORTHERN COAST, WHICH IS REPORTING 
SUSTAINED WINDS OF 21 KNOTS GUSTING TO 31 KNOTS WITH AN SLP OF 
995MB. OVERALL, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION 
BASED ON THE MSI AND RADAR IMAGERY. THERE IS HIGH CONFIDENCE IN THE 
INITIAL INTENSITY BASED ON THE PGTW DVORAK AND ADT ESTIMATES. 
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH STRONG POLEWARD AND 
EQUATORWARD OUTFLOW, LOW VERTICAL WIND SHEAR AND WARM SST (28C). 
THUS THE PRIMARY HINDRANCE IS INTERACTION WITH LAND, WHICH IS 
LIMITING INTENSIFICATION AT THIS TIME.

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: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 40 KTS AT 080212Z
   CIMSS ADT: 35 KTS AT 080540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: INTERACTION WITH LAND

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM

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. SLIGHT INTENSIFICATION IS ANTICIPATED PRIOR TO
LANDFALL NEAR TAU 06 WITH A PEAK OF 40 KNOTS LIKELY. AFTER
LANDFALL, 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 BY TAU 96.      

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 WITH A 90NM SPREAD IN SOLUTIONS AT TAU 48 BUT
DIVERGE AFTER TAU 48 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 24
WITH STEADY WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD.
 
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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