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What's Causing The Active Hurricane Season?

An image of Hurricane Genevieve
Facebook: NOAA NWS National Hurricane Center
Hurricane Genevieve

The Northeast has already felt the impacts of the remnants of one hurricane this year, during an Atlantic Hurricane season that is the most active to date. Even this far north up the Eastern Seaboard, Isaias left thousands without power for days. 

WAMC's Jim Levulis spoke with Jim Yoe, a scientist with the National Weather Service, about what’s ahead as the season nears its peak. 

Yoe: We predicted a very active hurricane season before it started. In fact, we've actually upgraded that prediction to be quite active. We're, at this point predicted that by the time we reach the end of the hurricane season, we'll have 19 to 25 named storms, you know, kind of almost running out of alphabet, they're typically in a year, we might have, I think, you know, 12 names twice a year, we've already had 11. And we have that is for the Atlantic basin. And we have three more systems that could possibly develop into the Atlantic now. So as we come into the peak season, you know, our seasonal forecast is does seem to be bearing out.

Levulis: And what is the reason for that uptick?

There's a number of factors that lead to you know, favorable conditions for the formation and development of tropical systems and hurricanes. Those include having a strong East African monsoon which we have this year. We have above average water temperatures in the equatorial Atlantic basin also in the Caribbean Sea in the Gulf of Mexico. And all those are you know that that warm water is one of the drivers for hurricanes. And the last thing is there's not very much wind shear over the Atlantic Ocean, that that that portion of the Atlantic Ocean where hurricanes form, wind shear kind of you can think of it's like a kind of tense to cut a hurricane development off, you know, with the winds at different levels or blowing at different speeds or different directions. There's not much of it. So it's kind of like a candle flame. That's, that's allowed to go up and reach its full extent, if you will. So all of those conditions are really bright for the SSA for forming hurricanes this year.

And Jim, you mentioned the overall number of storms in a hurricane season. How many storm systems is NOAA typically tracking at one time maybe in the height of the hurricane season?

Well, and again, that depends on how active a season it is. You tend to notice when you start getting three storms or more at a time. But, you know, as I say, right now, we're not tracking any storms in the Atlantic basin, but we do see three areas that could in time develop into Tropical systems. So no calls for making preparations. Yep, it's certainly for us. That's a lot to pay attention to.

Obviously, when it comes to hurricanes, we often think about the coastal areas, but increasingly it seems that at least from a layman's perspective, interior portions of the country are being impacted. In the WAMC listening area here in New York, interior New England Tropical Storm Isaias obviously swept through. How does the National Weather Service predict how the storm is going to behave once it reaches land and continues on a land based path?

We make predictions to cover the oceans and coastal regions and the entire all land areas of course, especially the US understates itself. So those models don't, don't stop when you when you get to the when you when you make landfall, of course, we have observations of the conditions that the factors that feed into the hurricane around the globe, and especially those looking for the west coast of Africa is up to the east pacific, where, for example, we track the El Nino or La Nina oscillation, because that also factors into how hurricanes grow. But you're right. We have seen hurricane systems or tropical storms that have carried in land with increasing strength. I know this a Madison, Wisconsin received some rain this year from a tropical system that we thought that was a I guess, I think that was from a tropical storm or crystal ball that it was kind of the first time in recorded history. Certainly no golf, golf storms. Those in the Gulf of Mexico can often come up to the Mississippi and payment you know and the fact region so well beyond the coast, you know, you don't see them as hurricanes but obviously not the storm surge and, and with winds that heavy but very often dropping far more rainfall than is commonly affected. And of course, that's one of the things that people will tend to lose track of with hurricanes and tropical storms. You know, we categorize hurricanes based on the wind speed, but a lot of the damage and the threat to lives and properties from the systems really comes from water rather than from wind. So in coastal regions, or water, I mean the storm surge and high surf even far away from the center of the storm. It can be dangerous for people you know, in in maritime occupations or simply at the beach, but also after making landfall. The inland flooding is always a huge risk. And of course, that's something people have to have to remember is if you're not on the coast, you may well be impacted. By the weather from a tropical system.

And I understand that NOAA has made some improvements to its satellites, what do those improvements allow the agency to do?

Well, we've been making improvements to the satellite server over a number of years. This didn't all just happen recently. But we do have a lot of modern satellite instruments that are helping us particularly now in our global and hurricane forecasting. So we use satellites that can measure the sea surface temperature, because that's a driver of the, you know, the energy source for tropical systems. We have imagers that are really sharp now just like you know, our digital cameras and how they've gotten to give us sharper pictures than they did 20 years ago. Well, the cameras that we use to track storm systems are much higher resolution, better quality than they used to be. So we see much finer detail. We have a better idea of the structure of the interior stores, we know more precisely where the With a low pressure center that storm is the best course is one of the basic starting pieces of information you need to have for predicting the track of a hurricane. Let's see some other things we have we have sensors, infrared and microwave sensors are provided those which are able to make measurements of the temperature and moisture inside even through the cloud. So particularly with the microwaves of the hurricane, and again, that you know, want to know how much energy is being transferred into the atmosphere. We measure that through the temperature and through that moisture. That also has the potential for how much rainfall we had. Finally, in our we have in the last couple of years, a new sensor called the Global Lightning Mapper, and we can actually see lightning inside the structure of a hurricane so we know where the severe weather is taking place inside of the storm system. Like so that's another nice we have telling, you know, is this system likely to intensify? Is it going to devolve into something a little milder? As time goes on? All those things together, give us a really good set of tools to use in our forecast process.

Jim is WAMC’s Associate News Director and hosts WAMC's flagship news programs: Midday Magazine, Northeast Report and Northeast Report Late Edition. Email: jlevulis@wamc.org
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