I had promised myself to take a quick look at the speed of the jet across eastern America after I heard from Tomasz Schafernaker it could to 250 mph earlier this week on the BBC forecast. So here’s a look at the winds at midnight on Friday night. I don’t promise that I’ve caught it at it at its peak but what the hell. I’ll have to make good on another one of my promises to revisit the code for this application and smarten it up, until then these graphics for the 300 hPa level will have to do. As you can see upper air charts have never been the same since the demise of the ocean weather ship network forty odd years ago, and the Met Office didn’t help by closing the upper air stations at Stornoway and Shanwell either.
As you can see the winds ahead of the cold trough across the Great Lakes at the 300 hPa level (~33,000 feet) were widely in excess of 150 knots down the eastern seaboard of America that night, as the low that spawned storm Ciara hurtled westward. Here is a more detailed look at the midnight ascent from Yarmouth Nova Scotia where the wind was blowing 201 knots (231 mph) at 250 hPa.