You Ought to Have a Look: All Eyes on Hermine

You Ought to Have a Look is a regular feature from the Center for the Study of Science. While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic. Here we post a few of the best in recent days, along with our color commentary.

This week, all eyes have been on Hurricane, now-Tropical-Storm, Hermine.

Since the Hermine coverage has been non-stop and ubiquitous, instead of highlighting anything in particular on the intertubes, we thought we’d give you our specific take on the events of this (and next) week. Here goes.

We’re about to take the national Rorschach test that accompanies headline storms, as the leftovers from Hurricane Hermine are going to spin away for a week off the mid-Atlantic coast, generating humongous seas and climate change blathering.

Dealing with the former won’t be better informed by the latter—an uneccessary and largely unjustified interloper/distraction.

The storm will be the result of an unhappy marriage between a hurricane or tropical storm remnant and a garden variety upper-atmospheric low pressure system. For reasons having everything to do with bad luck, the jet stream is going to be “blocked” in place for nearly a week, so that anything that would normally be steered from west to east is just going to sit. And sit.

The waters off the mid-Atlantic coast are near their seasonal maximum, and they’re also several degrees above normal. (Note—in the northeastern Atlantic, they’re several degrees below average.) That’s going to provide a tad more energy to the storm as it stalls out, but that’s not going to last long. A huge donut of 50-70mph winds sitting in the same place will mix out the surface warmth pronto, and what will be the main event will be more like a strong winter northeaster that gets stuck in one place, like the Ash Wednesday storm of 1962, which caused a huge amount of coastal damage from Cape Cod to South Carolina

If that repeated now, owing to the tremendous coastal development since then, it would easily be among the most expensive storm in our history. Fortunately (at least as of this writing) it looks like the persistent strong winds are going to be coming from the north, resulting in only modest (two to four foot) storm surges.

This is hardly the first time that a decaying hurricane has been enmeshed with a stagnant upper air storm. In fact, the resemblance between Hermine and 1972’s Hurricane Agnes is astounding.

Both came ashore rated as 80mph storms on the Florida panhandle. Neither actually generated an observed hurricane-force sustained wind on land. Both then burbled northeastward, to emerge off the Outer Banks and briefly resurrected as tropical cyclones. Both then were captured by a stagnant jet stream.

Both produced tremendous amounts of rain, with one slight difference. The Agnes remnant did it over an extensive area of the northeastern U.S., killing 122 people. Sixteen of these were in Washington, as normally torpid Rock Creek rose to the rooftops of cars on the adjacent Parkway in a matter of a few minutes. The U.S. Office of Emergency Management calls it “the most massive flooding in the history of the eastern United States.”

Agnes did this while spinning a loop over land. The Hermine remnant is forecast to spin three, but out over the water, all the while chunking out tremendous amounts of rain. We can only hope this is true, because all that’s going to cause is a week of impressive winds and gigantic waves. If this happens onshore (or very near-shore)…we don’t even want to think about it.

With regard to that Rorschach test, it should be duly noted that both the Ash Wednesday storm and Hurricane Agnes occurred during a time of global cooling. You don’t need global warming, and, because the Hermine remnant is going to mix away any unusually warm water very quickly, the real culprit will be the dumb luck of a weak hurricane intercepting a stalled jet stream.