Tropical Cyclone Prognostic Reasoning 2018-03-31T18:00:00Z

WTPQ30 RJTD 311800

RSMC TROPICAL CYCLONE PROGNOSTIC REASONING

REASONING NO.32 FOR STS 1803 JELAWAT (1803)

1.GENERAL COMMENTS

STS JELAWAT IS LOCATED AT 19.0N, 143.0E. INFORMATION ON THE

CURRENT POSITION IS BASED ON ANIMATED MSI. POSITIONAL ACCURACY IS

FAIR. THE SYSTEM IS IN AN UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT

UNDER THE INFLUENCE OF INCREASED VWS. THIS HAS CAUSED THE SYSTEM

TO WEAKEN OVER THE LAST SIX HOURS. INFORMATION ON CURRENT

INTENSITY IS BASED ON DVORAK INTENSITY ANALYSES.

2.SYNOPTIC SITUATION

THE SYSTEM IS MOVING EASTWARD UNDER THE INFLUENCE OF MID-LATITUDE

PREVAILING WESTERLIES. ANIMATED MSI SHOWS THE SEPARATION OF ACTIVE

CONVECTIVE CLOUD CLUSTERS FROM 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 EASTWARD UNDER THE INFLUENCE OF MID-LATITUDE

PREVAILING WESTERLIES UNTIL FT72. THE SYSTEM WILL THEN GRADUALLY

DECELERATE AND MOVE EASTWARD DUE TO WEAK STEERING FLOW UNTIL

FT120. THE JMA TRACK FORECAST IS BASED ON GSM PREDICTIONS, AND

REFERENCE TO OTHER NWP MODELS. JMA TRACK FORECAST CONFIDENCE IS

LOW DUE TO SIGNIFICANT DIFFERENCES AMONG NUMERICAL MODEL OUTPUTS.

4.INTENSITY FORECAST

THE SYSTEM WILL WEAKEN UNTIL FT24 DUE TO THE INFLUENCE OF

INCREASED VWS. THE SYSTEM WILL THEN MAINTAIN ITS INTENSITY UNTIL

FT72. THE JMA INTENSITY FORECAST IS BASED ON A CONSENSUS OF

GUIDANCE DATA INCLUDING GSM.

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