Reposting: Following Florence – Cold Blob now a Hot Topic

September 19, 2018

Gentle reminder: Those who follow these videos will get an early heads up on emerging topics in climate change.

Stefan Rahmstorf’s 2015 paper (with Michael Mann and Dark Snow Chief scientist Jason Box) is, in the wake of Hurricane Florence, a hot topic of discussion – mainly in terms of the “cold blob” south of Greenland, and its possible effects the behavior of storms, like possibly Florence, Sandy and Harvey – causing them to veer into the US mainland, and dawdle as they come ashore.

Washington Post:

In late August 2017, Hurricane Harvey made landfall in Texas on San Jose Island. Over the following five days, Harvey’s forward movement slowed to a glacial pace, essentially stopping over the greater Houston area, weakening in terms of wind speed but retaining an immense amount of moisture that eventually fell as rain in catastrophic amounts.

A year later, residents in the southeast and Mid-Atlantic may face the exact same scenario with Hurricane Florence, and the reason will be eerily similar.

A ridge of high pressure, extreme especially for this time of year, will develop just off the coast of New England, shunting the path of Florence toward the southeast coast. The strength of this ridge will be unprecedented in 30 years, according to forecast models.

Below, the cold blob has been reliably visible south east of Greenland for several years.

noaacoldblob0818

Last year, I posted this interview with ice core expert J.P. Steffensen on the history of sudden climate shifts related to the Atlantic circulation.

Union of Concerned Scientists:

Atlantic hurricanes tend to develop off the coast of Africa, then move in a north/northwest direction. By the time they reach the position Florence was in a couple of days ago, they tend to take a hard right turn toward the north/northeast, staying well away from the US. In fact, as reported by Brian McNoldy and the Washington Post, of the nearly 80 recorded storms that passed within 200 nautical miles of Florence’s position on Friday, none made landfall on the US coast.

Florence’s path, however, has been blocked by a ridge of high pressure in the atmosphere, which is essentially blocking the storm from moving northward and keeping it on a westward trajectory toward the coast instead.

Six years ago, when Sandy slammed into the coast of New Jersey, a “blocking ridge” over the eastern half of northern North America prevented Sandy from moving north. Never before had we seen hurricane take such a perpendicular path toward the Mid-Atlantic coastline.  One important difference between the paths of Sandy and Florence, however, is that during Sandy, the blocking ridge also prevented a low-pressure storm system coming from the west from moving north, so the two storms collided (hence the “Superstorm Sandy” moniker).

If you missed Jennifer Francis’ interview that I posted the other day, she does a good job of integrating what we know about how arctic changes might be having major effects on the storm tracks that affect us here in the temperate zone. Most relevant – 1:45 to 7:15.

 

 

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One Response to “Reposting: Following Florence – Cold Blob now a Hot Topic”

  1. dumboldguy Says:

    Not a single comment? Are we hoping that if we ignore this very bad news it will go away? That’s OK by me since we’re not doing much to counteract it—-may as well put our heads in the sand—-someone please tell me when it all magically goes away.


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