Remnant Low Sean

There has been a lot of news in the last 10 days, so it's easy to miss any stories about Tropical Storm Sean. About a week ago, the National Hurricane Center announced the formation of Tropical Storm Sean in the Eastern Tropical Atlantic. Over the next few days, Sean alternated between a Tropical Storm and Tropical Depression. It was a confusing time! It's not everyday that there is a storm named after me, so I asked Rico from the National Oceanic and Atmospheric Administration, someone who knows significantly more about hurricanes and weather than me, a few questions about Sean.

It's mid-October. Isn’t this late in the year for a named storm?

Rico:  It isn't late.  Hurricane season lasts until Nov 30 but after mid October the frequency of  tropical storms drops off. See https://www.nhc.noaa.gov/climo/#stca

Note there have been storms as late as Late December/early January.  The 2005 hurricane season that had storms in December 2005/January 2006.  The hurricane center started using the Greek alphabet to name storms then.  See https://www.nhc.noaa.gov/archive/2005/

At least as of Thursday, Sean was switching back and forth between a Tropical Storm and a Tropical Depression? What’s the difference and why can’t Sean make up his mind?

Rico: The difference between a tropical storm and a depression is the maximum wind speeds in the storm.  Once the maximum sustained wind speeds are >= 39mph, the depression becomes a tropical storm and it is given a name.

A couple of things are needed to maintain a tropical system.

 1) storms need warm waters (> 80F)

 2) low or no wind shear, wind shear is the change of wind speed and direction with height ( light winds are needed from the surface to high in the atmosphere)

 3) storms need to be surrounded by a moist air environment.

Sean's fickleness (from the limited amount of discussions I read from the hurricane center) was caused by wind shear and dry air intrusion.

What is the current status of Sean and any potential impact on land?

Well as you are probably aware, Sean has dissipated.  So no impacts whatsoever.  Wind shear and dry air were the causes. 

Finally, there was a storm named Sean in 2011. Is that too soon for another Sean?

The hurricane center repeats lists of names every 6 years. So "Sean" was on the list back in 2017 but that year there was no storm named Sean.  The number of storms failed to reach the "S' letter that year.   If the storm was really destructive, the name is removed from being listed again.

FYI,  the hurricane center has a bunch of info at its web site.  Check it out: https://www.nhc.noaa.gov/

While I like having my name in the news, it's even better that Sean isn't going to cause any damage.