Here’s why hurricane chasers fly their planes in weird patterns in storms


These flight models may look like boxes or stars, but they serve specific purposes for each individual storm.

Hurricane chasers don’t flee these storms like commercial airlines do. They fly right into them, but they don’t just fly in and around random storms. There is a method to madness.

There are two distinct groups of hurricane hunters, the National Oceanic and Atmospheric Administration (NOAA) and the US Air Force Reserve (USAF). Both organizations conduct tropical disturbance missions to record invaluable data used by forecasters at the National Hurricane Center (NHC).

For Hurricane Hunters, there are two main types of piloted missions, fixed and invested.

Fixed missions

Fixed missions are designated for systems that meet tropical cyclone ratings, such as tropical lows, tropical storms, and hurricanes. The main purpose is to mark the center of circulation, monitor wind speed and pressure changes, and other variables that are difficult for satellites to measure in space.

For fixed missions, “Alpha” is the most common flight model used to collect data in a tropical cyclone.

“The Alpha model is the standard profile we use for fixed missions, so it’s the one people are most used to seeing from us” Major Jeremy DeHart, meteorologist and air reconnaissance meteorological officer with the Air Force Reserve 53rd Weather Reconnaissance Squadron, noted. “The pattern consists of two legs flying in the intercardial directions, and when completed, closely resembles the Greek Alpha symbol including the crossed leg.”

Cardinal directions are the standard points on a compass: north, south, east, and west. The inter-cardinal directions are the diagonal points between: northeast, southeast, southwest and northwest.

Interestingly, the biggest and strongest storms tend to be the “easiest” to get through.

“From my perspective as an onboard meteorologist, the Alpha model is the ‘easiest’ to fly. Because we normally fly these on stronger storms, there’s not much question of where to fly. find the center of the storm, ”DeHart said. “Flights can be difficult, sure, but at the end of the day we’re just going to walk through the center of the storm, collect the data and send it to the NHC.”

Invest missions

The main objective of an investment mission is to determine if a system meets the definition of a tropical cyclone; storms that do not yet have a name or true tropical structure characteristics.

Inside the eye of a hurricane above 1000 feet

For investment missions, the NHC will often send estimated coordinates of where it thinks the traffic center is, i.e. where the missions will target their starting point.

However, investment missions by nature need to be a bit more flexible for flight models, simply because there are so many unknowns with these types of storms.

“You never know what you’re going to find, yet you always have to think of two or three steps forward. So it really forces us to think about the weather. [in each particular storm]”DeHart said.” Is it a closed trough or an open wave? Maybe it’s closed but just lying down? Is it about fighting against shear? Are there several small vortices competing to be the main center of circulation? Storms and low investments can be very tricky and require a lot of thought. “

Air Force hurricane chasers have a variety of flight models to choose from for investment missions: X, Delta, and Box, to name a few.

DeHart explains that missions are ideal for weaker and more uncertain storms. While the Model X may look like the Model Alpha, it is flown at much lower altitudes, typically between 500 and 1,000 feet.

“Once a system becomes a tropical storm or hurricane, hurricane chasers start flying at higher altitudes, ranging from 5,000 to 10,000 feet depending on the severity of the storm,” said Jessica Kendziorek, USAF 403 Wing Public Affairs Chief of Operations.

Flight levels for the Delta and Box models are generally equal to or less than 5,000 feet absolute altitude.

“The Delta and Box models are similar in that we’ll be flying around the outskirts of the forecast center to see if we can observe winds in the four quadrants of the storm that would indicate closed circulation. If we find closed circulation, we can go with confidence [find] the center; otherwise, we will continue the mission in ‘investment mode’, ”DeHart said.

NOAA focuses on research

NOAA hurricane chasers also perform fixed operational and investment missions (although the names may be different), but they usually have more research-oriented goals. They steal many unique flight models, with different types of aircraft, depending on the type of mission assigned.

The Hurricane Hunters also perform a third type of mission, which the Air Force rarely performs, according to DeHart, called synoptic missions.

For fixed missions, NOAA often uses a Figure 4, Rotated Figure 4, or Butterfly model.

“The Butterfly and Figure 4 models driven by the WP-3D through the storm are typically the ones used for [find] the traffic center “, said Jonathan Shannon, public affairs specialist for the Office of Marine and Air Operations at NOAA Aircraft Operations Center.

The rotation model in Figure 4 is as it seems; the pattern of figure 4 turned to the side.

“The goal of each flight is to collect data all around the center of the storm, and these models allow us to fly efficiently through the different quadrants of a storm,” said Nick Underwood, NOAA Hurricane Hunter. “This data helps predict the intensity of a storm, as well as determine exactly where the center is.”

For investment missions, the lawn mower and square spiral models are flown, to determine if there are any actual tropical features associated with the area they are investigating.

“The lawn mower model allows us to map a large area when we don’t have a center to aim at,” said Paul Flaherty, chief of the science branch at NOAA’s aviation operations center. “Once we are able to map a complete circulation (usually by finding a westerly wind), we will return to Figure 4 based on this newly identified central position.”

The Square Spiral pattern is a fact-finding mission intended to provide observations on the structure and characteristics, including information on the center of the vortex, if it exists.

There is a third type of unique mission flight model, often used to sample the surrounding atmosphere, which helps forecasters know the likely direction of the storm.

The Star 1 pattern focuses on a sweep of the outer edges of the system. The closely linked Star 2 model also performs an external sweep of the system, while also adding a circumference loop near the center of circulation.

Recently, NOAA’s Gulfstream IV flew over a Star-2 model around Hurricane Larry, to study the storm’s flow patterns and better determine where the storm was heading.

“The flight pattern you will typically see from our Gulfstream IV is a circumnavigation of the storm itself, as well as a sampling of the atmosphere around and before the storm,” Underwood said. “This data helps predict the path of the storm.”

Regardless of which entity is flying, operational missions are the backbone of the National Hurricane Center, tasked with providing vital critical information about a storm.

The NHC takes the data and uses it to provide advice and advisories to the public, so people know if Elsa, Ida, or Nicholas are still tropical storms or have become hurricanes.

We ended 2020 with a record 30 named storms in the Atlantic Basin and if this season looks like last year, we have a long way to go.


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