WTPQ31 RJTD 060600
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 9 FOR STS 2522 HALONG (2522)
1.GENERAL COMMENTS
  STS HALONG IS LOCATED AT 25.9N, 140.8E. INFORMATION ON THE CURRENT
  POSITION IS BASED ON ANIMATED MSI AND SURFACE OBSERVATIONS.
  POSITIONAL ACCURACY IS FAIR. CENTRAL PRESSURE IS 985HPA AND
  MAXIMUM SUSTAINED WINDS NEAR THE CENTER ARE 60KNOTS. 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. IT HAS ALSO DEVELOPED RAPIDLY
  OVER THE LAST 12 HOURS. INFORMATION ON THE CURRENT INTENSITY IS
  BASED ON DVORAK INTENSITY ANALYSES AND SURFACE OBSERVATIONS.
2.SYNOPTIC SITUATION
  THE SYSTEM IS MOVING NORTHWESTWARD ALONG THE SOUTHWESTERN
  PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH. ANIMATED MSI SHOWS THE
  ELONGATION OF A BAND WITH A CURVATURE SUGGESTING THE CSC. ANIMATED
  MSI SHOWS GOOD CLOUD CHARACTERISTICS OF ANTICYCLONIC OUTFLOW.
  WATER VAPOR IMAGERY SHOWS DRY AIR AROUND THE SYSTEM. GCOM-W/AMSR2
  89 GHZ MICROWAVE IMAGERY SHOWS THE SYSTEM HAS A BAND WITH
  CURVATURE INDICATING THE CSC.
3.TRACK FORECAST
  THE SYSTEM WILL MOVE WEST-NORTHWESTWARD ALONG THE PERIPHERY OF A
  MID-LEVEL SUB-TROPICAL HIGH UNTIL FT24. THE SYSTEM WILL THEN
  GRADUALLY TURN TO THE NORTHEAST BETWEEN TWO MID-LEVEL SUB-TROPICAL
  HIGHS UNTIL FT72. THE SYSTEM WILL THEN GRADUALLY ACCELERATE AND
  MOVE EASTWARD UNDER THE INFLUENCE OF MID-LATITUDE PREVAILING
  WESTERLIES 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 FT72 DUE TO THE INFLUENCE OF
  INTERACTION WITH HIGH SSTS, HIGH TCHP AND WEAK VWS. THE SYSTEM
  WILL THEN WEAKEN UNTIL FT120 DUE TO THE INFLUENCE OF INTERACTION
  WITH LOWER SSTS, REDUCED TCHP AND INCREASED VWS. THE INTENSITY
  FORECAST IS BASED ON A CONSENSUS OF GUIDANCE DATA INCLUDING GSM.
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