Day: September 28, 2010

Categories
Tropical Weather

TD Sixteen – a ragged system.

After the Hurricane Hunter recon plane went through TD Sixteen, it was found that the LLC was very broad with light winds of 20 knots or so (about 23 MPH) and the pressure was uniform over a long range. A normal system would have lower pressure within the center. Definitely not a typical cyclone. The forecast is that TD Sixteen may become a Tropical Storm either tonight or tomorrow. After 36 hours or so, the window will be closed for any further intensification as a large mid – to upper level trough that is digging down the southeastern US coast will keep intensification down. Some models are forecasting that TD Sixteen will become extratropical within 36-48 hours. The track of TD Sixteen has been shifted slightly to the west. UNLESS the structure of TD Sixteen improves and starts to tighten up, most of the strongest winds and rain will be east of the center and will be offshore away from the coast of Florida.

Visible Satellite image of TD Sixteen
Visible Satellite image of TD Sixteen/Cuba/Florida
AVN Satellite image of TD Sixteen
Models for TD Sixteen
Categories
Tropical Weather

Tropical Depression Sixteen

Invest 96L has been upgraded to Tropical Depression Sixteen as of the 11am Advisory from the NHC. The forecast is for TD sixteen to become a Tropical storm before it gets to South Florida BUT it will most likely begin the transition to a subtropical storm. I will try to explain the difference between a Tropical Storm and a Sub Tropical storm. In a normal tropical storm – the central portion or the “center” of a storm it is a “warm core” meaning all the strongest winds will be in the center. In a “cold core” system all the winds are displaced away from the center. Also in a cold core system – all the circulation is at all levels. In a warm core system such as a hurricane, this has a pool of warm air aloft generated by latent heating. The thermal wind changes direction at some altitude aloft due to the change in the temperature gradient and you get an anticyclonic circulation at high levels above the hurricane which you see as the wispy cirrus clouds that “push away” from the center.

I believe that South Florida will be ok as most of the convection is to the east of the center and will probably be offshore BUT everyone should keep tabs on this system as with any tropical system, things can change very quickly.

Visible Satellite image of TD Sixteen
Models for TD Sixteen