Thursday, June 04, 2020

TS Cristobal: June 3, Update A

A very busy day yesterday, but it's just as well for everyone that you didn't have my loopy ramblings because the news and events were truly loopy enough!

As expected, TD 3 became Tropical Storm Cristobal yesterday afternoon and made landfall in Mexico this morning about 20 miles west of the town of Cuidad del Carmen, in the state of Campeche. He brought some wind at landfall - winds were those of a mid-level Tropical Storm at 60mph (TS range: 39 -73mph) but he has weakened since then and currently has winds of 45mph, central pressure 995mb.

However, the bigger issue was the rain. Alas, he has been hanging out near Cuidad del Carmen all day - he is just south of the town - and is stationary, so although not a big storm, that entire part of the world has had a lot of rain for well over a day, which has resulted in flooding. His center is at 18.3N, 91.8W. 

He is expected to get his walking boots back on and start moving overnight, heading southeastward tomorrow before turning north on Friday...

You can see how much rain there was with this storm across parts of Mexico and central America in the satellite imagery: 

The dark red areas are really heavy thunderstorms - the sort that can spawn tornadoes. 

Cristobal is definitely a Tropical Storm, and may be a little stronger than the NHC give him credit for. The circulation is very strong throughout the entire troposphere (ooh...  jargon... how exciting!! :-)), which means that if he wasn't over land, I think he would actually be closer to hurricane strength. Fortunately for all, he is over land.

<Science Alert!> The Troposphere: Our atmosphere is divided into layers - like a delicious trifle or seven-layer dip. In each layer the air temperature either increases with height or decreases with height. The troposphere is one of these layers. It is the lowest layer of our atmosphere and extends up from the earth (ground zero if you like) to about 15-16km in the equatorial regions, and to about 8km in the polar regions of the planet. This is the layer of the atmosphere we live and breathe in. All our 'weather' essentially occurs in the troposphere. The troposphere is defined by decreasing air temperature with increasing height. You would know this if you climbed a mountain. Or the easier option, of course, 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 a few very strong cases, they can extend even higher into the next layer up - into the stratosphere, which is the layer of the atmosphere above the troposphere. The stratosphere is defined by air temperature increasing with height. The ozone hole is in the stratosphere. The top of the stratosphere is around 50km height and is marked by the stratopause. And the layer above that is mesosphere, where air temperature decreases with height again until the mesopause. Above that is the thermosphere, then the exosphere... and then we get to space.<End Science Alert!>

A Science Alert! followed immediately by a Technical Alert! How rare is that?!? ;-)

<Technical Alert!> It's really useful to know that temperatures decrease with increasing height in the troposphere. This gives us a clue about how strong a storm and it’s convection (rain, thunder etc.) is from the satellite images. The satellite imagery above is the infrared imagery and shows the temperature at the tops of the clouds. Higher cloud tops means a more turbulent atmosphere and stronger convection, but it also means colder cloud top temperatures. The red areas are the coldest cloud tops and they correspond to very heavy rain, strong winds, a lot of thunder, tornadoes… basically everything and the kitchen sink. Orange areas are less strong – thundery weather, strong winds, heavy rain. Yellow would be strong winds and rain, green is mostly rain with some wind, and then it gets to light rain/just cloudy where we see blue and gray.<End Technical Alert!>

Although the forecast calls for TS Critobal to weaken tomorrow and become a tropical depression again (because he is over land), until his circulation decreases he will retain his structure - I can see why the NHC think he will reform when he emerges back into the Gulf. 

The longer he stays over land, the weaker he will be of course. At the moment there are two competing things that will come into play once he is over water - the water is really warm in that part of the Gulf, which means he'll get stronger, but there is also strong wind shear, which will inhibit his development. 

The track will depend on how strong he is and when in the next two days he actually gets moving over water, so I will look into that tomorrow. Those of you in the northern Gulf states should be ready for a Tropical Storm anyway I reckon.

That's it for the Gulf. Meanwhile, in India, cat 1 level Tropical Cyclone Nisarga hit near Mumbai today, definitely causing some additional troubles on top of the pandemic! 

I'll be back tomorrow. 

Stay safe, be well!

Twitter: jyovianstorm
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 local weather service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know. 

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