WTPQ31 RJTD 041800
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 4 FOR TS 2504 DANAS (2504)
1.GENERAL COMMENTS
  A TD PREVIOUSLY LOCATED AT 20.2N, 117.7E HAS BEEN UPGRADED TO TS
  (DANAS) STATUS. TS DANAS IS LOCATED AT 20.1N, 117.2E. INFORMATION
  ON THE CURRENT POSITION IS BASED ON ANIMATED MSI AND SURFACE
  OBSERVATIONS. POSITIONAL ACCURACY IS FAIR. CENTRAL PRESSURE IS
  996HPA AND MAXIMUM SUSTAINED WINDS NEAR THE CENTER ARE 35KNOTS.
  THE SYSTEM IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT UNDER THE
  INFLUENCE OF HIGH SSTS, HIGH TCHP AND WEAK VWS. THIS HAS CAUSED
  THE SYSTEM TO DEVELOP OVER THE LAST SIX HOURS. INFORMATION ON THE
  CURRENT INTENSITY IS BASED ON DVORAK INTENSITY ANALYSES AND
  SURFACE OBSERVATIONS.
2.SYNOPTIC SITUATION
  THE SYSTEM IS ALMOST STATIONARY DUE TO WEAK STEERING FLOW.
  ANIMATED MSI SHOWS CB CLUSTERS GATHERING AROUND THE CSC. ANIMATED
  MSI SHOWS THE CLOUD CHARACTERISTICS OF ANTICYCLONIC OUTFLOW ARE
  NOW DISTINCT. WATER VAPOR IMAGERY SHOWS DRY AIR AROUND THE SYSTEM.
  NOAA-21/ATMS 85 GHZ MICROWAVE IMAGERY SHOWS THE SYSTEM HAS ACTIVE
  CONVECTIVE CLOUD CLUSTERS AROUND THE CSC.
3.TRACK FORECAST
  THE SYSTEM WILL MOVE SLOWLY NORTHWARD ALONG THE PERIPHERY OF A
  MID-LEVEL SUB-TROPICAL HIGH UNTIL FT24. THE SYSTEM WILL THEN MOVE
  NORTHEASTWARD ALONG THE PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH
  UNTIL FT48. THE SYSTEM WILL THEN MOVE NORTH-NORTHEASTWARD ALONG
  THE PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH UNTIL FT72. THE
  SYSTEM WILL THEN REMAIN ALMOST STATIONARY DUE TO WEAK STEERING
  FLOW UNTIL FT96. THE SYSTEM WILL THEN MOVE SLOWLY NORTHWARD ALONG
  THE PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH UNTIL FT120. THE
  TRACK FORECAST IS BASED ON GSM PREDICTIONS, AND REFERENCE TO OTHER
  NWP MODELS. TRACK FORECAST CONFIDENCE IS FAIR UNTIL FT48 BUT LOW
  THEREAFTER DUE TO SIGNIFICANT DIFFERENCES AMONG NWP MODEL OUTPUTS.
4.INTENSITY FORECAST
  THE SYSTEM WILL DEVELOP UNTIL FT48 DUE TO THE INFLUENCE OF
  INTERACTION WITH HIGH SSTS, HIGH TCHP AND WEAK VWS. THE SYSTEM
  WILL THEN MAINTAIN ITS INTENSITY UNTIL FT96 DUE TO THE INFLUENCE
  OF INTERACTION WITH HIGH SSTS, HIGH TCHP, LAND AND DRY AIR. THE
  SYSTEM WILL THEN WEAKEN UNTIL FT120 DUE TO THE INFLUENCE OF LAND.
  THE INTENSITY FORECAST IS BASED ON A CONSENSUS OF GUIDANCE DATA
  INCLUDING GSM.
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