8 September 2018

If You Live On The Eastern Seaboard, It’s Time To Worry About Florence

Posted by Dan Satterfield

There are a lot of satellite pictures and scary model forecasts being posted online, but this image is what concerns me most about Florence. The waters off the Eastern Seaboard this September are like a salty bathtub.

I’ve been pretty quiet here about the tropics this week and for good reason. Long range weather model forecasts are (as John Nance Garner described the office of Vice President) not worth a bucket of warm spit. In addition, tropical cyclones, at the position of Florence earlier in the week, have historically curved north and in only a couple of cases been a threat to the U.S. Eastern Seaboard. So yes, it was worth watching but not worth taking the long-range guidance too seriously. A good fact to remember is that all models are wrong, but they sometimes give good information.

In the past 24 hours, things have changed.

Thanks to GOES-16 we can see high res images with lightning flashes in real time.

The guidance continues to be more consistent in tracking Florence toward the coast and more importantly, looking at the upper air charts, this forecast looks reasonable. The storm is about to move over much warmer water with the wind shear relaxing, and this argues for rapid strengthening. The guidance also is in good agreement that Florence will be a major/severe hurricane in 72 hours, and if it approaches the coast it will have unusually warm ocean water beneath it. This increases the risk of it being a severe hurricane and it also means that the threat of flooding rains is higher. Just like Houston last year when Harvey arrived.

Climate change made Harvey worse, and it will likely do the same if Florence makes landfall. Look at the map at the top of this post for the answer why. Also look at the chart below showing how the water levels have changed at the mouth of the Chesapeake Bay:

Therefore: It’s time to worry.

I don’t know exactly where Florence is heading. Anyone who tells you they do knows little about tropical meteorology. The threat to the U.S. East coast is increasing significantly though, and if you live anywhere between Savannah in Georgia to the Jersey Shore, you need to start thinking hard about what you will do (and what you will need) if a Category 4 or 5 hurricane is 24 hours away. You may be in just that situation in less than 84 hours as I write this. I live on the Eastern Shore of Maryland, and I may be in just that situation in 84 hours.

See that cone around the storm? The width of that cone is the average error of the NHC track forecasts at each forecast time. That means Florence has an equal chance of being ANYWHERE in that cone. NOT in the middle of it.

Some Advice to Remember This Coming Week

  1. Hurricanes deaths are almost always flood-related and not wind-related.
  2. Hurricane damage is almost always flood-related and not wind-related.
  3. Trust advice from NOAA Forecasters and broadcast meteorologists who have a CBM seal from the American Meteorological Society. (If they have it, they will display it on air and on their social media pages)
  4. If you’ve not been in the eyewall of a hurricane, you’ve not been in a hurricane.
  5. A category 2 hurricane is nothing like a category 5 hurricane. It’s the difference between tripping in the driveway and being pushed off a roof. Quit laughing, I’m deadly serious.

Lastly, do the meteorologists (like me) who work at NOAA/and in media a favor. Don’t ask us what time it will hit your house or if some social media post is real. We are going to be too busy to answer you and please do not retweet or share it. Also, that scary picture of the storm going around on social media is probably a hoax, and that shark swimming up a freeway was five years ago. We’ve seen them all before. Really.

Oh, and don’t send us questions about dropping a nuclear weapon on it. First of all, you’ll just make it mad and another reason this is a bad idea: Radioactive Rain.

PS To the DOD folks working on the Dover AFB NEXRAD Doppler Radar. I know it suffered a lot of damage from the storm last week, but please try and Fix it by Wednesday, even if you have to steal parts from another one.