Will “Big Bertha” be a big deal?

Early this morning (Monday) what was tropical storm Bertha strengthened into the first hurricane of the 2008 Atlantic hurricane season. Now the big question is what happens next?

The official forecast track from the National Hurricane Center calls for the storm to continue to move to mostly the northwest for the next 3 days or so. In days 4 and 5, the storm is expected to begin a turn to the north and if it does like most storms of this trajectory do, it will likely turn to the northeast where it will be sheared apart by the jet stream and race harmlessly out to sea.

The storm is expected to strengthen a little more during this time with the official intensity at 90 mph by 2am Friday. Please keep in mind though, that while forecast paths are very good this day and age for the most part, we still have a lot of work to do in terms of intensity forecasts. This is because the track of a storm is determined by large scale weather features (synoptic scale) such as frontal boundaries, upper level high and low pressure areas, and in some instances the jet stream. The intensity of a storm, however, is determined by both larger synoptic scale phenomenon and smaller mesoscale and microscale features in the atmosphere. Inside the storm, hurricane hunters do a great job of gathering good meso and even microscale data which is the only reason intensity forecast are as good as they are. However, at this tiny scale of motion, conditions change by hour if not by the minute and computer models are just not good enough yet to catch those tiny, tiny little details that can impact the storms intensity in a huge way.

Notice I said "not good enough yet." I believe we have only scraped the surface in terms of hurricane forecasting. Forecast models and more importantly the weather data that goes into them are getting every season and forecast accuracy is beginning to show that. Ten years ago, the NHC forecasts only went out 3 days. However, as technology and the science improved, our 5 day forecasts are now as accurate as the 3 day forecast was then!

As I said, we (the meteorological community) have a lot of work left to do, especially with intensity forecasting, but that work is being done and the results are exciting. It's hard to believe that before the first weather satellite Tiros went up 48 years ago, all we could do was wait for ships to warn us of impending hurricanes. Not even half a century later, we are with decent accuracy predicting where and how bad a hurricane will be in 5 days. Is a 7 day forecast in our future? Probably not anytime soon, but most meteorologists would have never dreamed 50 years ago we'd be issuing 5 day forecast for hurricanes today.

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