WTPQ31 RJTD 080600
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO.17 FOR TY 2522 HALONG (2522)
1.GENERAL COMMENTS
  TY HALONG IS LOCATED AT 30.5N, 137.7E. INFORMATION ON THE CURRENT
  POSITION IS BASED ON THE EYE IN ANIMATED MSI AND SURFACE
  OBSERVATIONS. POSITIONAL ACCURACY IS GOOD. CENTRAL PRESSURE IS
  935HPA AND MAXIMUM SUSTAINED WINDS NEAR THE CENTER ARE 100KNOTS.
  THE SYSTEM IS IN A NEUTRAL ENVIRONMENT FOR DEVELOPMENT UNDER THE
  INFLUENCE OF HIGH SSTS, WEAK VWS AND DRY AIR. THIS HAS CAUSED THE
  SYSTEM TO MAINTAIN ITS INTENSITY 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 MOVING NORTH-NORTHEASTWARD BETWEEN TWO MID-LEVEL
  SUB-TROPICAL HIGHS. ANIMATED MSI SHOWS THE SYSTEM HAS AN EYE.
  ANIMATED MSI SHOWS GOOD CLOUD CHARACTERISTICS OF ANTICYCLONIC
  OUTFLOW. WATER VAPOR IMAGERY SHOWS DRY AIR AROUND THE SYSTEM.
  NOAA-20/ATMS 85 GHZ MICROWAVE IMAGERY SHOWS THE SYSTEM HAS AN EYE.
3.TRACK FORECAST
  THE SYSTEM WILL MOVE NORTH-NORTHEASTWARD BETWEEN TWO MID-LEVEL
  SUB-TROPICAL HIGHS UNTIL FT12. THE SYSTEM WILL THEN GRADUALLY
  ACCELERATE AND MOVE EAST-NORTHEASTWARD UNDER THE INFLUENCE OF
  MID-LATITUDE PREVAILING WESTERLIES UNTIL FT72. 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 MAINTAIN ITS INTENSITY UNTIL FT24 DUE TO THE
  INFLUENCE OF INTERACTION WITH HIGH SSTS, INCREASED VWS AND DRY
  AIR. THE SYSTEM WILL THEN WEAKEN UNTIL FT72 DUE TO THE INFLUENCE
  OF INTERACTION WITH LOWER SSTS, REDUCED TCHP AND INCREASED VWS.
  THE SYSTEM WILL TRANSFORM INTO AN EXTRATROPICAL CYCLONE BY FT72.
  THE INTENSITY FORECAST IS BASED ON A CONSENSUS OF GUIDANCE DATA
  INCLUDING GSM.
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