Watching the upcoming interaction of #Grace & an upper-level trough N of the Antilles (diagnosed as +PV anomaly in the upper-tropopshere).

Grace's short-term intensity could have a large impact on if this is a negative (high VWS) vs. more neutral (moderate VWS) interaction. pic.twitter.com/6QJSkrMksS

— Philippe Papin (@pppapin) August 14, 2021