Chantal, the third tropical storm of the 2013 Atlantic Hurricane Season, has formed out in the middle of the Atlantic Ocean. The National Hurricane Center began issuing advisories on Chantal at 11PM on Sunday night, skipping tropical depression status as satellite data was confident enough for forecasters to directly classify the system as a tropical storm.
Chantal has 40 MPH winds and is moving rather briskly for a storm that originates so far out in the Atlantic, with a forward speed of 26 MPH. Here is the forecast track from the NHC's 11PM EDT advisory, showing the storm's expected movement over the next 5 days. Do not focus on the projected path of the center of Chantal, especially given the margin of error (denoted by the cone). Tropical storm force winds usually extend dozens of miles beyond the center of the storm.
Chantal is expected to be steered along to the west-northwest over the next few days by a strong high pressure center in the Atlantic, and will slowly turn more towards the north as the high weakens a bit and westerly shear starts to affect the storm. The NHC expects some weakening at that point due to the combination of wind shear and interaction with the tall mountains of Hispaniola and western Cuba.
Here were the sea surface temperatures as measured on Sunday, and many apologies for an image from The Weathertainment Channel:
Here's a spaghetti plot model showing where each individual model expects the center of Chantal to go over the next week or so. None of these models will be 100% correct. The NHC usually averages them out and leans towards whichever model is performing the best at the moment. Always trust the NHC's forecast rather than looking at spaghetti plots. These are non-quality-controlled model forecasts, not an official forecast issued by experts.
Tropical systems have a long history of doing things that forecasters don't expect and models don't pick up on. Interests in the Caribbean and southeastern United States need to keep a close eye on Chantal as it approaches land. These systems have a tendency to strengthen (or weaken) unexpectedly and/or veer off its projected course. Forecasters and models are much better at predicting where the storm will go than how strong it'll be when it gets there.
This could be the first serious threat of the year, simply given its distance from land and the amount of time it will spend over water before it makes any sort of landfall. Keep a close eye on it, and I'll post more updates as necessary. The forecast track will slowly change as refinements are made over the next few days.