Tropical Storm SONCA Advisory Cu, 14.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTY-TWO)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 13.3N 112.4E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 288 NM SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A DISORGANIZED
WESTWARD MOVING SYSTEM IN THE SOUTH CHINA SEA WITH ITS MAIN
CONVECTION SHEARED WESTWARD OF AN EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC). THE WESTERN HALF OF THE MAIN CONVECTION HAS ALREADY
MADE LANDFALL OVER THE INDOCHINA PENINSULA VIA VIETNAM. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC.
THE INITIAL INTENSITY IS BASED ON A RECENT SCATTEROMETRY PASS THAT
SHOWED 25-KT WINDS 50NM FROM THE LLCC ON THE NORTHWEST QUADRANT. THE
INITIAL INTENSITY IS ALSO SUPPORTED BY THE PGTW DVORAK ESTIMATE OF
T1.5.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG WESTWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.
FORECAST DISCUSSION: TD 22W WILL CONTINUE WESTWARD UNDER THE STR
AND MAKE LANDFALL NEAR QUY NHON, VIETNAM, AROUND TAU 20 BEFORE
TRACKING INLAND. THE FAVORABLE ENVIRONMENT WILL FUEL A MODEST
INTENSIFICATION TO A PEAK OF 35KTS BY TAU 12. AFTER LANDFALL, THE
RUGGED TERRAIN AND HIGH VWS WILL RAPIDLY ERODE THE SYSTEM, LEADING
TO DISSIPATION BY TAU 36 AS THE SYSTEM CROSSES INTO CAMBODIA.
MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
AND SPREADS TO 140NM BY TAU 36, LENDING MEDIUM CONFIDENCE IN THE
JTWC FORECAST. AFUM IS THE SOLE LEFT-OF-TRACK OUTLIER.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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