Monday, July 09, 2018

Ex-TS Beryl and Tropical Storm Chris: July 8, Update A

Goodness me, what happened to the weekend? I'd like to propose that we all switch to 3-day weekends and 4-day work weeks...Yes? :-)

Tropical Storm Chris
Chris continues to grow and now has winds of 60mph, central pressure of 1005mb. This makes him a mid-sized Tropical Storm (TS range: 39-73mph). He is at 32.5N, 74.5W and is meandering ESE at a whopping 2mph off the Carolina's coast. There is some wind shear, which you can see in the satellite imagery (this is the water vapor imagery - purple indicate the drier parts of the atmosphere, green are for the areas with higher water vapor):

As we saw yesterday, he has strong circulation over the entire lower half of the troposphere, and there is a little bit showing up in the upper troposphere which means he is going to continue to strengthen and could be a hurricane soon. There is some wind shear, but it is to his northeast (as you can see with the clouds streaming off to the northeast in the satellite image) and his center is still clear of that. Until he moves to the east, there is not too much to stop him from slowly getting stronger because he will remain over water that is 28-29 deg C, with the upper ~100m warmer than 26.5 deg C. 

The forecast is that he will loiter with intent in the same area tomorrow, but start moving on Tuesday and then get whisked away to the northeast. I will go with this. If you live along the coast you should keep an eye on the storm surge once he starts moving northwards. A hurricane is a low-pressure system and has winds that move in a counter-clockwise direction. Those winds will tend to push water onto the coast in locations that are north of the center, and so there will be an increase in water levels along the coast, and those to the south will get a decrease in water levels. To look up storm surge levels for yourself, there are instructions in the Technical Alert! in this post:  

Ex-Tropical Storm Beryl
Beryl is pretty weak now... actually, she's not even a tropical storm. There are a number of things that tell us this. First, she is at the officially at 15.8N, 62.4W and heading WNW at 26mph which is too fast for a proper, self-respecting tropical storm. Second, there is very little circulation in the middle levels of the troposphere which indicates she's not a tropical storm, and it's not too strong in the lower levels either. Third, although her official wind speed is 40mph (central pressure is 1010mb), it's actually a little less. It's only 40 so she stays on our radars, but she's weaker than that.

From the water vapor satellite image above, she still has a few buckets of rain which she's just dumped mostly over the Dominca/Guadaloupe area, but she is not a wind-storm of any note anymore.

For now this is my last update on Beryl.

Until tomorrow, ciao,

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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