WTPQ32 RJTD 061800
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO.36 FOR TS 2020 ATSANI (2020)
1.GENERAL COMMENTS
TS ATSANI IS LOCATED AT 22.3N, 119.7E. INFORMATION ON THE CURRENT
POSITION IS BASED ON ANIMATED MSI AND RADAR IMAGERY. POSITIONAL
ACCURACY IS FAIR. CENTRAL PRESSURE IS 1000HPA AND MAXIMUM
SUSTAINED WINDS NEAR THE CENTER ARE 45KNOTS. THE SYSTEM IS IN A
NEUTRAL ENVIRONMENT FOR DEVELOPMENT UNDER THE INFLUENCE OF LOWER
SSTS, REDUCED TCHP, WEAK VWS, DRY AIR AND LAND. 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 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.
3.TRACK FORECAST
THE SYSTEM WILL MOVE WESTWARD BETWEEN TWO MID-LEVEL SUB-TROPICAL
HIGHS UNTIL FT12. THE SYSTEM WILL THEN GRADUALLY ACCELERATE AND
MOVE SOUTHWESTWARD ALONG THE PERIPHERY OF A MID-LEVEL SUB-TROPICAL
HIGH UNTIL FT24. THE TRACK FORECAST IS BASED ON GSM PREDICTIONS,
AND REFERENCE TO OTHER NWP MODELS. TRACK FORECAST CONFIDENCE IS
FAIR BECAUSE ALL NWP MODELS ARE IN CLOSE AGREEMENT.
4.INTENSITY FORECAST
THE SYSTEM WILL GRADUALLY WEAKEN UNTIL FT12 DUE TO THE INFLUENCE
OF INTERACTION WITH LOWER SSTS, REDUCED TCHP AND INCREASED VWS.
THE SYSTEM WILL THEN WEAKEN UNTIL FT24 DUE TO THE INFLUENCE OF
INTERACTION WITH LOW SSTS, LOW TCHP AND INCREASED VWS. THE SYSTEM
WILL WEAKEN TO TD INTENSITY BY FT24. THE INTENSITY FORECAST IS
BASED ON GSM PREDICTIONS.
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