Tropical storm Karen is 250 miles from the mouth of the Mississippi river with maximum sustained winds of 50mph, and it’s looking like the perfect manifestation of a lackluster 2013 hurricane season. To be sure, folks should heed warnings from the National Hurricane Center and their local National Weather Service offices. It’s just that in past seasons the descriptions being applied to Karen would barely be noticed outside the affected areas.
The storm had been expected to grow to hurricane strength, but that’s no longer the case, with landfall strength of probably less than 60mph. It’s expected to skim the Louisiana shoreline on Saturday night before hitting the Alabama–Florida border during the day on Sunday.
Tropical storm force winds can be dangerous to those who are caught out in them. They could knock down some trees. One must also understand that forecasting winds is not something that forecasters do well. At this point, however, there isn’t likely be any sort of major structural damage.
The storm is expected to have rainfall totals of 2-4in and perhaps locally higher from southeastern Louisiana, which is nothing to scoff at. Yet New York City already experienced the same scenario and perhaps worse in 2013, when the remnants of tropical storm Andrea hit the city in early June. I didn’t exactly hear much from the national press about that one.
There will be effects on beach areas, though those shouldn’t be anything to write home about. Forecasters think there should be “minor” coastal flooding and “minor” beach erosion. Only rip currents and surf are described as “high”.
Unless something unexpected happens, we still will not have had a single storm strike land with hurricane force winds this season. Last year, there were three.
The problem for Karen is what has plagued storms the entire 2013 season: wind shear. Wind shear is basically when the wind speed and/or direction is inconsistent in the different layers of the atmosphere. Tropical storms need consistency to be able to grow, and differing winds do not allow it.
The underlying baseline of warm sea surface temperatures for tropical development has been there. That’s why it seems like we will hit the minimum range of the 13-20 pre-season tropical storm forecast from the National Oceanic Atmospheric Administration (Noaa).
The issue is that, like in Karen, the wind shear has been far higher than anticipated in the Atlantic ocean. That caused a vast overestimation in the expected number of hurricanes. In its pre-season forecast, Noaa predicted that we would get between seven and 11 hurricanes. The actual number at this point has been two.
It marked yet another season in which Mother Nature has outsmarted man. The pre-season forecast should be correct 70% of the time. As I noted in September: “Seven of the last 11 years have featured the actual number of storms falling outside the pre-season range, including 2009 and 2012. Given that we’re going to need one amazing end to the 2013 season to reach seven hurricanes, it’s looking like eight out of 12 seasons and three out of the last five forecasts were wrong.”
Now, I want to re-emphasize that people living in the region shouldn’t take anything for granted and should listen to the weather authorities. Hurricanes can change on a dime.
It’s just that Karen seems, at this point, like it’s going to continue the trend of a season that hasn’t lived up to the hype.