Making the Connection: Did Ice Loss Amplify Sandy?

Watch above, my interview with Jennifer Francis, when, on September 18, 2012, she predicted “a very interesting fall”, due to changes in northern sea ice, more open water, and more heat and moisture entering the atmosphere.

Now, in an article with Cornell researchers, Francis further explores the reasons why Hurricane Sandy may have taken that final, nasty, and very unusual left turn…

Cornell University:

If you believe that last October’s Superstorm Sandy was a freak of nature — the confluence of unusual meteorological, atmospheric and celestial events — think again.

Cornell and Rutgers researchers report in the March issue of Oceanography that the severe loss of summertime Arctic sea ice — attributed to greenhouse warming — appears to enhance Northern Hemisphere jet stream meandering, intensify Arctic air mass invasions toward middle latitudes, and increase the frequency of atmospheric blocking events like the one that steered Hurricane Sandy west into the densely populated New York City area.

The article, “Superstorm Sandy: A Series of Unfortunate Events?” was authored by Charles H. Greene, Cornell professor of earth and atmospheric sciences and director of Cornell’s Ocean Resources and Ecosystems program; Jennifer A. Francis of Rutgers University’s Institute of Marine and Coastal Sciences; and Bruce C. Monger, Cornell senior research associate, earth and atmospheric sciences.

The researchers assert that the record-breaking sea ice loss from summer 2012, combined with the unusual atmospheric phenomena observed in late October, appear to be linked to global warming.

A strong atmospheric, high-pressure blocking pattern over Greenland and the northwest Atlantic prevented Hurricane Sandy from steering northeast and out to sea like most October hurricanes and tropical storms from the Caribbean. In fact, Sandy traveled up the Atlantic coast and turned left “toward the most populated area along the eastern seaboard” and converged with an extratropical cyclone; this, in turn, fed the weakening Hurricane Sandy and transformed it into a monster tempest.

Superstorm Sandy’s extremely low atmospheric pressure and the strong high-pressure block to the north created violent east winds that pushed storm surge against the eastern seaboard. “To literally top it off, the storm surge combined with full-moon high tides and huge ocean waves to produce record high water levels that exceeded the worst-case predictions for parts of New York City,” write the researchers.

Greene, Francis and Monger add: “If one accepts this evidence and … takes into account the record loss of Arctic sea ice this past September, then perhaps the likelihood of greenhouse warming playing a significant role in Sandy’s evolution as an extratropical superstorm is at least as plausible as the idea that this storm was simply a freak of nature.”

My video on Sandy below speaks to the freak left turn, and its causes, starting at about 4:00

Minnesota Public Radio:

We’ve just witnessed a massive hurricane that did something no other tropical system has done in the past – Make a sharp left turn in the Atlantic and plow headfirst into New Jersey & New York in late October.

Here’s why Sandy’s track was unprecedented for a hurricane this late in the tropical season.

-Late October jet streams are usually well established far enough south that any northward moving Atlantic hurricanes are pushed eastward into the Atlantic by fast moving jet stream winds before they reach the East Coast.

-According to Jeff Masters of WxUndeground, Sandy is just the 2nd hurricane to ever hit the relatively protected (recessed) Jersey Coast. The only other hurricane to hit New Jersey was the “Vagabond Hurricane” in 1903, and that one hit in September when the jet stream is usually further north.

In weather geek speak we call these highly amplified jet stream patterns “blocking patterns” because they force the jet stream to meander into big north-south kinks and loops…instead of flowing more rapidly from west to east.

Blocking patterns have always formed in certain seasons, but tend to become less common in fall…only about 2% of the time vs. 6% in winter & spring.

There is a growing body of evidence that blocking patterns may be increasing as the Arctic warms. The blocking pattern this week over Greenland, combined with a “negatively tilted” (backwards leaning) low pressure trough over the eastern USA sucked Sandy back to the NW at the last minute into New Jersey, instead of shoving her out to sea.