WTPQ32 RJTD 281800
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO.20 FOR STS 2509 KROSA (2509)
1.GENERAL COMMENTS
  STS KROSA IS LOCATED AT 27.5N, 143.5E. INFORMATION ON THE CURRENT
  POSITION IS BASED ON ANIMATED MSI AND SURFACE OBSERVATIONS.
  POSITIONAL ACCURACY IS GOOD. CENTRAL PRESSURE IS 975HPA AND
  MAXIMUM SUSTAINED WINDS NEAR THE CENTER ARE 60KNOTS. THE SYSTEM IS
  IN AN UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT UNDER THE INFLUENCE
  OF WEAK VWS, LOW TCHP AND DRY AIR. THIS HAS CAUSED THE SYSTEM TO
  WEAKEN 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 WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN
  PERIPHERY OF A MID-LEVEL SUB-TROPICAL HIGH. ANIMATED MSI SHOWS THE
  SYSTEM HAS 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. GPM/GMI 89
  GHZ MICROWAVE IMAGERY SHOWS THE SYSTEM HAS A BAND WITH CURVATURE
  INDICATING THE CSC.
3.TRACK FORECAST
  THE SYSTEM WILL GRADUALLY DECELERATE AND MOVE NORTH-NORTHWESTWARD
  BETWEEN TWO MID-LEVEL SUB-TROPICAL HIGHS UNTIL FT12. THE SYSTEM
  WILL THEN REMAIN ALMOST STATIONARY BETWEEN TWO MID-LEVEL
  SUB-TROPICAL HIGHS UNTIL FT72. THE SYSTEM WILL THEN MOVE SLOWLY
  NORTHWARD BETWEEN TWO MID-LEVEL SUB-TROPICAL HIGHS UNTIL FT120.
  THE TRACK FORECAST IS BASED ON GSM PREDICTIONS, AND REFERENCE TO
  OTHER NWP MODELS. TRACK FORECAST CONFIDENCE IS FAIR UNTIL FT24 BUT
  LOW THEREAFTER DUE TO SIGNIFICANT DIFFERENCES AMONG NWP MODEL
  OUTPUTS.
4.INTENSITY FORECAST
  THE SYSTEM WILL GRADUALLY WEAKEN UNTIL FT24 DUE TO THE INFLUENCE
  OF INTERACTION WITH WEAK VWS, LOW TCHP AND DRY AIR. THE SYSTEM
  WILL THEN MAINTAIN ITS INTENSITY UNTIL FT120 DUE TO THE INFLUENCE
  OF INTERACTION WITH WEAK VWS AND LOW TCHP. THE INTENSITY FORECAST
  IS BASED ON A CONSENSUS OF GUIDANCE DATA INCLUDING GSM.
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