Atlantic's Hermine Is A Big Deal (UPDATED)

For the latest post on Hermine GO HERE.

Update Thursday PM

Hermine has grown in strength, and may even make landfall as a Category 2 storm. At least a strong Category 1.

The right front quadrant of the storm is where the main "punch" (of winds) is located. If the storm winds come into an embayment, they can really build up the storm surge. Look at this image:

You can see the right front quadrant of the storm heading right into Apalachee Bay. Barrier islands to the west of the bay's head, and the communities right in the bay, are very much at risk for severe flooding.

Here is a blowup of part of the NWS's experimental storm surge product for the area:

You can see the increase in storm surge intensity/risk in the bay.

Also, there is a small possibility that the storm, which will turn "extratropical" as it passes over Florida and joins an existing storm system, will later move out to sea in an area conducive to re-formation. Not too likely but the idea is being bandied about.

Update (Noon Thursday):

It is very likely that Hermine will become an actual hurricane by the end of business day today, or during the early evening. It is really starting to look like one now, as of this writing.

The storm is likely to make landfall (as a hurricane?) before mid day tomorrow (Friday). There is a very serious storm surge threat from some point east of Apalachicola, all the way over to about Spring Hill, or even a bit farther south (heading towards Tampa). Especially at risk are areas around Big Bend Wildlife Management area and Suwanee River, where embayments may focus the storm surge.

Some of these places may have storm surges over over 9 feet above the ground.

After that, the National Weather Service is trying to be vague, because Hermine will interact with a large existing low pressure system. How much rain, where, how much wind, where, all that, is not clear. By the time the storm gets to near Norfolk, it might not even be near Norfolk. This could become a land threatening Nor'Easter affecting New York or Boston, or it could to out to sea and rain mainly on boats. Stay tunes.

This is not a major hurricane, but it is likely to be a significant flooding and rain event for a lot of people over a large area. This is also going to mess up Labor Day weekend, which will have a significant economic impact on many areas where people usually visit and recreate.

Original Post:
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 Douglas 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 landfall, 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.