Daily Archives: Wednesday, July 20th, 2011
We now have two tropical storms moving across the northern Atlantic. First though, an update on Tropical Storm Bret. I will then take a deeper look into our new tropical-ish storm, and then a look at the upcoming week in the tropics.
Tropical Storm Bret
Tropical Storm Bret has been very persistent over the last day. Hurricane hunters have been in and out of Bret numerous times a day since its genesis, and the results from each flight has brough back really valuable information each time. They flew out today and found out that the center still had a 2 degree celsius difference inside to outside of the storm. This is important because one of the requirements of a Tropical Cyclone is that it must be warm-cored. tropical cyclones are similar to the human body in that the temperature inside must be warmer than outside, or the system will die. The latest cyclone phase diagrams, which also shows the temperature of the core of a cyclone, show that Bret has a shallow warm core. This is showed below:
Bret looks like he has about 24 hours or less left before it loses that difference between inner core temperature and outer core temperature. Bret is doing really well considering that it has 20-30 mph of shear blowing all of its clouds toward the south. This is another side effect of the giant high pressure area parked over the Central United States.
Tropical Storm Cindy
Somewhat of a surprise came across the wires today when the National Hurricane Center upgrade invest 99L to Tropical Storm Cindy. Cindy is to the east of Bret by a couple hundred miles in much cooler water with 25 mph shear overhead. Cindy is probably closer to subtropical than tropical. The difference here is that it has a very shallow warm core, and already has some extratropical characteristics such as an upper level trough helping some of the lifting mechanisms which are creating the shallow warm core. Cindy probably will not last 24 hours in the subtropics as conditions are only getting less favorable. Winds may get up to 55-60 mph before she goes truly post-tropical due to an increase in forward speed and some added upper level mechanisms.
A look ahead
The tropics look bright for the week ahead. There are two vigorous tropical waves that are crossing the Atlantic in the middle of a sea of dry air and dust. The southeastern third of the Atlantic is closed off to any development in my opinion. When the first tropical wave gets into the Caribbean, development is possible. A few models have hinted at a significant storm a little too close to land than I would like.