Wednesday, September 14, 2016

Tropical Storms Ian and Julia: September 13, Update A

Well I was going to start this post with a bit of a rant about Tropical Storms forming over land and what were they thinking... but then I looked at the data and sure enough, there she is... Tropical Storm Julia did, indeed, form over Florida. Well done Florida.

So... starting with our newest Miss Julia...

Tropical Storm Julia
She was named a Tropical Storm by the NHC this evening (11pm EST was the first advisory) and is currently at 30.3N, 81.6W, right over the center of Jacksonville. She is heading NNW at 9mph:

For those of you who have eyes, you will see that she developed over land and it looks like she will stay over land as a Tropical Storm for a day at least. She is very close to the Gulf Stream which has very deep warm water so she is going to be pulling a lot of her strength from that, which is why she looks like she has a lot of convection (but mostly over the Gulf Stream and close to the coast) as you can see in this satellite image: 

Even though her center is over land, there is a lot of wind shear which is keeping the clouds and rain to the northeast of her center and mostly over water or along the coast. It looks like NE Florida, Georgia, and S. Carolina are going to get buckets of rain along with some thundery weather (the orange and red areas in particular are strong thunderstorms). 

In this case, I agree with the NHC that she is definitely a Tropical Storm, although she barely a storm with winds of 40mph (TS range: 39-73mph), central pressure 1009mb. The reason I would agree with the NHC on this one is because she has a vorticity (circulation) structure throughout the lower half of the troposphere that looks like a tropical storm. Here are the vorticity maps from the lowest level of the troposphere (850mb) and the middle troposphere (500mb):

The main role that Julia will play is to bring you all rain, not too much on the wind front (unless they are gusts in those strong thunderstorms). 

You may be thinking that a tropical storm forming over land has never happened before in the Entire History of History, and perhaps this is actually a sign that everyone should just abandon the State of Florida before anything really weird happens. Well you would be wrong in thinking that. This storm-forming-over-land business has happened before, and besides, I'm not sure we can truly measure what 'really weird' in Florida actually means. ;-) In 1988, Beryl became a Tropical Storm over Louisiana and in 1997, Danny became a storm over North Carolina. Florida, you are not alone. 

Tropical Storm Ian
I have a really busy day today/tomorrow/this week, so I'll just keep it light on Ian. He is still out there, and although they say he is stronger with winds of 50mph, central pressure of 998mb, he looks weaker - both in the vorticity (circulation) maps (see above - the mid-troposphere red blob that is Ian doesn't look very well defined at all), and also from his satellite imagery:

He is under that wind shear, so I expect that he will continue to struggle. But as he is far from Anywhere-in-Particular (at 27.6N, 52.8W) and heading to Nowhere-in-Particular (NNW at 13mph), I will not say too much more about him (for now).

Must run for ce soir!
A bientot,

Blogs archived at
Twitter @JyovianStorm
DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know.

No comments: