WTPQ30 RJTD 231800
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO.20 FOR TY 2017 SAUDEL (2017)
1.GENERAL COMMENTS
TY SAUDEL IS LOCATED AT 18.0N, 113.9E. INFORMATION ON THE CURRENT
POSITION IS BASED ON ANIMATED MSI AND SURFACE OBSERVATIONS.
POSITIONAL ACCURACY IS FAIR. CENTRAL PRESSURE IS 975HPA AND
MAXIMUM SUSTAINED WINDS NEAR THE CENTER ARE 65KNOTS. THE SYSTEM IS
IN AN UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT UNDER THE INFLUENCE
OF DRY AIR. THIS HAS CAUSED THE SYSTEM TO WEAKEN OVER THE LAST SIX
HOURS. INFORMATION ON THE CURRENT INTENSITY IS BASED ON SURFACE
WINDS DATA ESTIMATED FROM SATELLITE SCATTEROMETERS AND SURFACE
OBSERVATIONS.
2.SYNOPTIC SITUATION
THE SYSTEM IS MOVING SLOWLY WESTWARD DUE TO WEAK STEERING FLOW.
ANIMATED MSI SHOWS THE SHORTENING OF A BAND WITH CURVATURE
SUGGESTING THE CSC. ANIMATED MSI SHOWS CLOUD CHARACTERISTICS OF
ANTICYCLONIC OUTFLOW HAVE BECOME OBSCURE. WATER VAPOR IMAGERY
SHOWS DRY AIR IN THE DIRECTION OF THE MOVEMENT.
3.TRACK FORECAST
THE SYSTEM WILL MOVE WESTWARD ALONG THE PERIPHERY OF A MID-LEVEL
SUB-TROPICAL HIGH 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 WEAKEN UNTIL FT72 DUE TO THE INFLUENCE OF
INTERACTION WITH DRY AIR AND LAND. THE SYSTEM WILL WEAKEN TO TD
INTENSITY BY FT72. THE INTENSITY FORECAST IS BASED ON GUIDANCE
DATA.
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