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First Atlantic tropical depression forming?

By: Dr. Jeff Masters,

Take a look at the gathering clouds over the western Caribbean Sea, just north of Honduras. All the ingredients are in place for the first tropical depression of the season to form--surface pressures are starting to fall, upper level winds are creating a favorable outflow pattern of high cirrus clouds, and there is low vertical wind shear and warm 87 degree Fahrenheit water. I'd estimate that Western Caribbean systems at this stage of organization this time of year form into tropical depressions about 30% of the time. It is not well understood why so many of these type of systems fail to form into tropical depressions when all the ingedients needed are seemingly in place; this is an area of intensive research.

If a tropical depression does form, the GFS computer model predicts it will move north into the Gulf of Mexico and possibly threaten the U.S. Gulf Coast. However, this computer model is very unreliable at predicting the motion of tropical systems that haven't formed yet. For the most reliable information on developing tropical systems, read the National Hurricane Center's
Tropical Weather Outlook
, which is updated daily at 11am, 5pm, 11pm, and 5am EDT during hurricane season.

Dr. Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

I just took a look at the 12Z canadian model global panels and the 12Z ECMWF to see what they doing with this weakness. and it seems to agree with the 18Z gfs and the ECMWF in the formation of this depression and most likely tropical storm. But the Canadian Global is much slower in its progress towards the gulf coast, also shipping it towards Florida by t+108/120 compared to the GFS taking it to LA in ~t+90. The ECMWF meanwhile is taking it into LA, but not until ~t+132.

it'll be interesting to see what happens with this system if anything, now that a temporary west atlantic ridge has established in the east US and how fickle tropical systems areon models.

btw, for reference, my experience with the canadian global in tropical situations is the following: it can sometimes spin up stuff too much in the tropics, but when it gets a spin-up right, it seems to get the actual path decently while being too fast with its forward speed. That's at least what I have seen with it over the last 6 years.
I'm in Tampa so my eye is on this as well.

BTW, anyone know if there are any studies that relate the spring and early summer rainfall in Florida to Tropical Storm activity later that year. Since the Bermuda high is a factor for landfalling hurricanes I wonder how it effects rainfall in Florida?
Beginning of the Destructive Hurricane season of 2005.