Atlantic’s Hermine Is A Big Deal [Greg Laden's Blog]

For a while there it looked like the Atlantic might develop up to four simultaneous named storms, but that has not worked out. One of the storms will never get a name, one of the disturbances now looks like it may never be a storm. Gaston continues to chug away towards the Azores.

But one of these four weather events is now a named storm that will matter.

Tropical Storm Hermine is a global warming enhanced storm that will produce record rainfall events, catastrophic inland flooding, and likely, coastal storm flooding, in many locations in the US east.

Paul Douglans of Aeris Weather notes that this storm reminds him, somewhat of Sandy, because of its bigness and wetness and potential to reach far inland. It will not be as bad as Sandy, but, he notes, “there is a growing potential for disruptive weather all up and down the East Coast from Friday into Sunday; coastal Georgia and the Carolinas right up I-95 into Washington D.C. and New York City may be impacted by 40-60 mph winds, flash flooding and coastal flooding and beach erosion as Hermine churns north.”

Also like Sandy, a blocking pattern in the Atlantic will cause Hermine to stay longer off the coast than otherwise.

Places that normally flood are likely to flood. The storm will come over land at the base of the Florida Peninsula and the Florida Panhandle. It is possible that the storm will be a weak Category One hurricane just before lanfall, but not likely. It will then cross florida and run up the coast, either just on land or just off shore. One model h as the storm curving back from the Atlantic into southern Newe England, another model has it staying on land until New York City, then curving back out over Long Island. That gives you the range of uncertainty for the storm’s activity in several days from now.

But the track for the first several days is pretty well understood. Across the base of florida, then across Georgia, South Carolina, and into or near the Tidewater area, staying near the coast the whole time, more or less straddling the strandline.

It will be windy and wet with a lot of rainfall. The loss of Labor Day business will be bad for tourism regardless of any damage to such facilities that may occur as well.

Is Hermine enhanced by global warming?

Hermine is a weather event. Global warming caused by the human release of greenhouse gasses (and other human effects) is a climate phenomenon. So how can we possibly connect them?

Well, we have moved well past the days when one could pose such a lame brained question. Climate is weather, long term, and weather is climate, here and now. So, if climate is fundamentally changed, then the wether is fundamentally changed. The question is not whether weather that drenches or withers and climate wither are bound! The question is, what ways are a particular untoward weather event and the recent changes in the climate bound?

Here’s how.

Warmer seas and warmer air, causing generally more moisture in the air; and changes in air currents due to Arctic warming and other effects, causing a more uneven distribution of moisture in the air causing big dry areas and big wetter areas, and large wet blobs to form up and then move more slowly than usual across the landscape, make something like this storm (which at the base of it could have happened anyway) be bigger, wetter, slower-moving and thus rainier.

Climate Signals has a nice summary here.