Saturday, May 26, 2018

Subtropical Tropical Storm Alberto: May 26, Update A

Typical timing - a storm over the weekend and a long weekend in the US to boot. You didn't have picnic or outdoor BBQ plans in Florida did you?
Just like yesterday, and as expected for today, Subtropical Storm Alberto is still very weak and quite disorganized. He is currently centered at around 22.8N, 85.2 W and is heading N now at 13mph, which is a better pace for any self-respecting storm. His central pressure is 999mb and his winds are still border-line Tropical Storm/Tropical Depression at 40mph (TS range: 39-73mph).  
If you squint and have a bit of imagination, you can just about pretend there is a center of circulation in the satellite image above - it's in the southern Gulf of Mexico. It's not as obvious as yesterday though. 
Given how disorganized he is, and that the circulation in the middle of the troposphere (oh happy day! it's the first <Science Alert!> of the season! ;-)) is not well formed, I'm not sure I would even call him a Subtropical Storm at the moment. The convection, which is still being swept off to the east due to wind shear, is because he is still over some warm water, which is also quite deep - the upper ~125m of the water column is warmer than 26 deg C. There is also some dry air coming in still, which is also inhibiting his development.
<Science Alert!> The Troposphere: Our atmosphere is divided into layers - like a delicious layer-cake (that goes very nicely with a cup of tea). In each layer, the air temperature either increases with height or decreases with height. The troposphere is the name of one of these layers - it is the layer closest to the earth and it is the layer that we live and breathe in. This lowest layer of our atmosphere extends up from the earth (ground zero) to about 15-16km above our heads in the equatorial regions, and to about 8km in the polar regions of the planet. All of our 'weather' essentially occurs in the troposphere. The troposphere is defined by decreasing air temperature with increasing height - the higher you go, the colder it gets. You would know this if you climbed a mountain or the easier (and more often used) option is to just look at pictures of mountains and see the snow at the top (known as the 'Flat Florida Option'). ;-) The top of the troposphere is called the tropopause. Strong tropical storms have clouds that reach as high as the tropopause - and in some cases, if they are very strong, they can push into the next layer up - into the stratosphere. The stratosphere is defined by air temperature increasing with height. The ozone hole is in the stratosphere. The top of the stratospheric layer is around 50km and is marked by the stratopause. The layer above that is the mesosphere, where the air temperature decreases with height again... and so on until we get to space where there are no yummy layer-cakes to be found. :-) <End Science Alert!> 
His track is more-or-less the same as yesterday - heading to the northern Gulf coast:
I can see why the track is like this - he is heading towards a low pressure area that is slowly moving across the southern states. Given the speed of the forward motion of Alberto and this low, it is definitely possible that he will make landfall in the Florida panhandle/Apalachicola area.
Got to go and recycle some wine bottles (have to make room for the new season supply!) and buy ice cream in preparation for hurricane season (in California). ;-) I'll be back later with an update, and some thoughts to wrap up the 2017 season... (just in time).  
These remarks are just what I think/see regarding tropical storms (my storm blog). If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast. This is not an official forecast.

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