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By Olivia Sanchez
As the Atlantic hurricane season commences, Florida State University boasts several specialists engaged in leading research concerning these natural calamities.
Mark Bourassa serves as a professor of Meteorology in the Department of Earth, Ocean and Atmospheric Science, is the associate director of the Center for Ocean-Atmospheric Prediction Studies (COAPS), and is affiliated with the Geophysical Fluid Dynamics Institute. These organizations strive to advance our comprehension of air-sea interactions and their implications for the Earth, atmosphere, cryosphere, and ocean systems.
Bourassa’s research focuses on air/sea interactions, remote sensing pertaining to air and sea dynamics, precipitation, and data integration. His area of expertise lies in the transfer of energy and momentum between the ocean and atmosphere, particularly in the domain of remote sensing of surface winds.
1. What are your thoughts on NOAA’s hurricane outlook for 2025?
The NOAA’s projection (60% likelihood of above-normal activity; 30% chance of normal; 10% likelihood of below-normal) appears plausible. This suggests a season that’s anticipated to be slightly more active than average. There exists a broad spectrum of activity in ‘normal’ and above ‘average.’ The count of storms likely isn’t the statistic that affects people most significantly. What truly matters is the trajectory of these storms and their intensity when making landfall. Additionally, there are broader repercussions related to precipitation, flooding, swells, and tornadoes. These nuances exceed our forecasting capabilities, which is why the storm count is emphasized.
2. What are the most significant hurdles in predicting rapid intensification, and why is it still challenging?
These queries are tough to address as the primary issue often lies in experts not recognizing the underlying cause. This was the case for rapid intensification until recently. Our latest collaborative investigation (Yang et al, 2024, 2025) reveals that one major obstacle is modeling how sea spray alters the energy transfer from ocean to atmosphere. Hurricane winds extract numerous tiny droplets of seawater from the waves. The evaporation of these droplets modifies the energy exchanged between the ocean and atmosphere. The energy required to fuel a tropical cyclone is largely sourced from condensing water vapor as ascending air cools. The speed of this energy release depends on the ascent rate and altitude of the air, which correlates with how much warmth the ocean imparts to the air.
Warmer air is lighter than the surrounding atmosphere. This scenario enhances its buoyancy, promoting an upward movement. Our findings suggest that sea spray accelerates this heating rate. It’s akin to boosting the tropical cyclone’s engine, facilitating greater energy release from water vapor. The rising air must be replenished with air flowing into the storm at the surface, increasing the influx of warm, moist air into the eyewall, which further amplifies the energy feed to the storm.
Our research significantly enhances our model’s capability to capture sudden fluctuations in hurricane intensity. We’ve demonstrated that a crucial missing element is how sea spray influences enhanced vertical motion and inflow of surface winds.
Additional factors are likely significant and still need to be pinpointed. For approximately 25% of rapid intensification incidents, incorporating sea spray into the model physics yields only marginal improvements, with persistent considerable intensity errors. There must be other physical elements that we have yet to identify.
3. Can you elaborate on the limitations of satellite sensors in detecting near-surface wind fluctuations during severe storms, and what innovations are anticipated?
The challenges vary based on the technology employed to monitor surface winds. Some explanations include:
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- We can either see through rain or we cannot.
- When visibility through rain is possible, we require longer radar wavelengths, which generally comes with limited resolution unless the satellite is equipped with a larger and pricier antenna.
- There are methodologies that offer high-resolution winds and can penetrate rain, with the caveat that directional accuracy is compromised. Another limitation of this technology is its restricted coverage over the ocean surface.
In conclusion, we aim to see through rain, achieve high resolution, and maintain consistent coverage of storms. Different strategies can fulfill two of these objectives, but currently, achieving all three remains elusive.
4. How does the global oceanographic and meteorological observation network improve short- and long-term hurricane forecasts?
Seasonal forecasts rely heavily on water temperature and global wind patterns. The global observation network is excellent for identifying extensive spatial variability linked to surface temperature, wind, moisture, clouds, and precipitation—all of which can be assessed. These observations can be amalgamated to provide a robust estimate of large-scale wind patterns, which typically persist for weeks to months.
The forecasts of individual storm trajectories are largely contingent on the broader scale wind patterns that tropical cyclones traverse, as well as the positioning of fronts and high-pressure systems. Weather satellites excel in supplying this data. Intensity is influenced by the rate at which the storm traverses warm waters, the depth and temperature of those waters, interactions with land and other weather systems (like fronts), and the moisture content in mid-levels. The synergy between the oceanographic and meteorological observing systems is beneficial for assessing these characteristics along the anticipated path of the storm.
5. In your experience mentoring meteorologists or emergency responders, what are the most prevalent misconceptions or knowledge gaps concerning hurricanes?
A prevalent misconception pertains to the size of a hurricane. Many envision the eye of a hurricane when considering scale. While individuals recognize these as large systems, they often fail to grasp the true magnitude, typically underestimating it by about a factor of 10. Most are aware that track forecasts have drastically improved, but they tend to overlook the significant consequences that even a slight deviation in track can have on those with property.
Additionally, many underestimate how swiftly a hurricane’s intensity can fluctuate beyond the forecasted predictions. These rapid changes are considerably more challenging to model compared to the slower, better-forecasted changes. Our modeling advancements are not yet operational. Most individuals do not comprehend the substantial productivity loss that occurs in preparation for storms well before they make landfall. Inaccurate forecasts could lead to even greater productivity losses and a higher risk to lives.
People often visualize eyewalls as straight cylinders, but they are actually tilted. Observing radar images of the eyewall from high altitudes may lead to misconceptions about the position of the eyewall’s surface winds.
The post Five Questions with Mark Bourassa: Examining the current state of hurricane forecasting appeared first on Florida State University News.
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