WDPN31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2N 108.6E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 21 NM NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION 13W (THIRTEEN) CONTINUING ON A NORTHWESTWARD TRACK AT 9
KNOTS OVER THE PAST SIX HOURS.  MUCH OF THE LOW-LEVEL CIRCULATION
CENTER (LLCC) WESTERN PERIPHERY HAS ENCROACHED VIETNAMS EASTERN
SHORELINE AND PROCEEDS TO MOVE INLAND.  ASSOCIATED BROAD TURNING 
PERSISTS OVER THE SOUTH CHINA SEA, WITH TD 13W MESOVORTEX LLCC NEARING 
THE VIETNAM COAST.  FRAGMENTED SPIRAL BANDS WITH DEEP CONVECTION 
PERSIST, YET THE FLARING CONVECTION COLLOCATED WITH THE LLCC HAS 
GREATLY DIMINISHED SINCE 250600Z. THE INITIAL POSITION IS PLACED WITH 
MEDIUM CONFIDENCE BASED ON A 251200Z GOES-H9 CHANNEL-7 89 MICROMETER 
INFRARED IMAGE. THE INITIAL INTENSITY OF 25 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON PERSISTENCE, KNES SUBJECTIVE 
DVORAK INTENSITY ESTIMATE, AND CIMSS OBJECTIVE INTENSITY ESTIMATES 
LISTED BELOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: RIDGING OVER SOUTHERN CHINA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   KNES: T1.0 - 25 KTS
   CIMSS ADT: 30 KTS AT 251230Z
   CIMSS AIDT: 31 KTS AT 251230Z
   CIMSS DPRINT: 31 KTS AT 251200Z
   CIMSS DMINT: 27 KTS AT 251008Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL DEPRESSION 13W (THIRTEEN) IS FORECAST
TO CONTINUE ON A NORTHWESTWARD TRACK UNTIL MAKING LANDFALL PRIOR TO
TAU 12. THE ENVIRONMENT REMAINS MOSTLY FAVORABLE WITH WARM SEA
SURFACE TEMPERATURES (30-31 DEGREES CELSIUS) AND LOW VERTICAL WIND
SHEAR (10-15 KNOTS), OFFSET BY THE GRADUALLY INCREASING INFLUENCE
OF LAND. THE SYSTEM IS EXPECTED TO BEGIN DISSIPATION OF LAND NEAR
TAU 12 AND HAVE DISSIPATED BY TAU 24. THE FORECAST CONFIDENCE FOR
BOTH TRACK AND INTENSITY IS MEDIUM.

MODEL DISCUSSION: GLOBAL NUMERICAL MODELS ARE IN EXCEPTIONAL
AGREEMENT THAT TROPICAL DEPRESSION 13W (THIRTEEN) WILL TRACK
NORTHWEST THROUGH TAU 6, AND THEN SHIFT TO A MORE WESTWARD TRACK
THROUGH DISSIPATION (TAU 24). THOUGH SLIGHT INTENSIFICATION IS
POSSIBLE OVER THE NEXT FEW HOURS, INTENSITY GUIDANCE SUGGESTS TD
13W WILL BEGIN DISSIPATION OVER LAND AS A LOW INTENSITY TROPICAL
DEPRESSION NEAR TAU 12, HAVING DISSIPATED BY TAU 24.

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