WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MA-ON) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.3N 117.4E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 254 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
CONVECTION WRAPPING INTO A LOW LEVEL CIRCULATION CENTER (LLCC) IN
THE CENTRAL SOUTH CHINA SEA. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE MSI LOOP, ALONG WITH A 232303Z
SSMIS 89GHZ IMAGE. UPPER-LEVEL CONDITIONS REMAIN MARGINALLY FAVORABLE
WITH MODERATE WESTWARD OUTFLOW, WARM (29-30C) SSTS, BEING OFFSET
BY MODERATE TO STRONG NORTHEASTERLY VERTICAL WIND SHEAR. THE INITIAL
INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN
AVERAGE FROM PGTW, RJTD DVORAK ESTIMATES, AND AUTOMATED DVORAK
TECHNIQUES (ADT).

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 41 KTS AT 232340Z

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

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 10W IS CONTINUING ON A WEST-NORTHWEST TRACK
AND WILL CONTINUE THROUGH THE NEXT 72 HOURS AS IT REMAINS UNDER THE
DIRECT INFLUENCE OF THE STR OVER CENTRAL CHINA. TS MA-ON IS
EXPECTED TO REACH A PEAK INTENSITY OF 60KTS SHORTLY AFTER TAU 24.
TS MA-ON NORTHEASTERLY SHEAR HAS INCREASED, CAPPING ANY GREATER 
DEVELOPMENT AND IS FORECAST TO REMAIN STRONG. THE STORM IS NOW 
EXPECTED TO MAKE LANDFALL JUST BELOW TYPHOON STRENGTH NEAR YANGJIANG, 
CHINA. ONCE THE SYSTEM MAKES LANDFALL, THE INTENSITY WILL RAPIDLY 
ERODE AS IT CONTINUES TO ENCOUNTER STRONG VERTICAL WIND SHEAR AND 
INTERACTS WITH THE RUGGED TERRAIN.

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN TIGHT AGREEMENT WITH A
NARROW SPREAD FROM 35NM AT TAU 12 TO A GRADUALLY SPREAD OF 110NM BY
TAU 72, LENDING HIGH CONFIDENCE IN THE OVERALL JTWC TRACK. THE GFS
AND HWRF INTENSITY GUIDANCE HAVE THE HIGHEST PEAK INTENSITIES
BETWEEN 65 AND 70 KNOTS. JTWC HAS HEDGED THE INTENSITY SLIGHTLY
LOWER DUE TO THE STRONG VERTICAL SHEAR TO THE NORTH. THE OVERALL
INTENSITY CONFIDENCE IS LOW DUE TO THE LIMITED MODEL INTENSITY
GUIDANCE FROM A MAINTENANCE ISSUE AT FNMOC. 

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