Wednesday, September 28, 2016

Early Thoughts on Tropical Storm Matthew

The strong tropical disturbance we've been tracking in the Atlantic since this past weekend achieved sufficient organization to be classified as Tropical Storm Matthew on Wednesday morning. It made a quick leap from tropical wave to strong tropical storm as the Hurricane Hunters discovered maximum sustained winds around 60 mph. No change in strength was noted with the 4 p.m. advisory.

Tropical Storm Matthew advisory from 4 p.m. Wednesday, Sept. 28.

What We Know

While the eastern Caribbean is known as a bit of a death bed for developing tropical systems, it appears that won't be the case this time around. Conditions appear favorable for gradual strengthening and the official forecast calls for Matthew to become a hurricane by Friday, potentially strengthening further to a Category 2 (or stronger) over the weekend.

Most of our computer model guidance is in agreement with this line of thinking, showing steady strengthening through the next 5 days. Note that there are several models indicating the potential for Matthew to become a 'major' hurricane (Cat. 3 or stronger).

What We Don't Know

Most of you are probably wondering if Matthew will make it into the Gulf of Mexico. That is a key point that we cannot make any conclusions on yet and likely may not be able to for at least another couple of days.

If you simply looked at the so-called 'spaghetti plots' available on a number of sites online, you might think the Gulf of Mexico is in the clear.

The problem with these spaghetti plots is that they do not include one of our most reliable models, the European. It's also a lot more difficult for the average person to get a look at the European ensembles because much of the European model data is only available through sites that charge a fee.

What are the ensembles? The European is one of a few global models run at a high resolution. At the completion of each run, it's then run an additional 50 times at a slightly lower resolution with small adjustments made to the starting conditions in the atmosphere for each run. The advantage to ensemble forecasting is that it gives us a much better look at the range of possibilities and uncertainty for a given storm.

In this case, the ensembles of the European model paint a much different picture, with many indicating the potential for Matthew to move into the Gulf of Mexico by the mid to latter part of next week. The tweet above from Meteorologist Ryan Maue with WeatherBell shows how the possible tracks for Matthew are all over the board from the Euro ensembles. Consider each cluster of red concentric circles as a possible track from Matthew. This is likely a result of what is expected to be a complex steering pattern that develops by next week. In simple terms, subtle changes in the steering mechanisms or the strength of Matthew could have big impacts on the track.

Bottom Line

It is still very early in the game for Tropical Storm Matthew. Forecast confidence is pretty high through the next 3-4 days, but drops off considerably as we head into next week. The majority of the guidance keeps Matthew on the Atlantic side of Florida, but the well respected European gives us reason to pay attention.

Stay tuned, and as always, make sure your hurricane plan is in place just in case Matthew or anything else should decide to head our way.

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