SCIPP Research Sheds New Light on Key Elements of Tropical Systems
8/28/25 – NOAA’s Southern Climate Impacts Planning Program (SCIPP) just published its annual report. It includes new research findings on three key elements of tropical systems: a lengthening tropical season, stalling storms, and tropical cyclone size at landfall.
SCIPP publishes fascinating reports tailored to the south central region of the U.S. including Texas, Oklahoma and Louisiana.
The government/university partnership conducts research to understand climate hazard trends and patterns that are useful to decision makers. The information below is summarized from their annual report.
Tropical Season Lengthens 16 days
SCIPP analysis of Atlantic hurricane season length from 1970 to 2022 found that storms are forming increasingly earlier AND later in the season. In 1970, the first named storm formed around July 27th. However, by 2022, the date shifted to around May 31st. That represents an increase of season length of 11 days per decade … just on the front end.
On the back end, in 1970, the last named storm dissipated around October 24th. However, in 2022, the last storm dissipated around November 18th. This represents a roughly 5-day per decade shift, say the researchers.
“While improvements in observational practices raised some concerns about data quality,” they say, “our results suggest that the primary driver of season expansion is the earlier onset and prolonged persistence of favorable conditions for tropical cyclones, such as warm sea surface temperatures, elevated humidity, and reduced wind shear.”
The researchers recommend that the National Hurricane Center consider moving the start of hurricane season to May 15th to heighten awareness of these early season storms. They have presented their work widely within the scientific community. For more information, see Dr. Vincent Brown’s virtual presentation to the Inland Marine Underwriters Association.
Stalling Storms Increasing 1.5% Per Year
SCIPP researchers also found seasonality in stalling storms. Stalling is most common in October (17.3% of storms) and least common in August (8.2%).
Their analysis showed a significant increase in annual stalling frequency during the satellite era (1966–2020) at 1.5% per year.
They also found an increase in the proportion of stalling storms relative to all storms.
SCIPP 2024-2025 Annual Report
Stalling storms were also significantly more likely to reach major-hurricane intensity.
These findings have been presented to stakeholders, academic audiences, and emergency managers to help them better prepare for future stalling events in vulnerable regions.
“Size at Landfall” Increasing Later in Season
The third featured project was a database of tropical cyclone size at landfall.
Size at landfall is critical in determining the extent and severity of storm impacts.
SCIPP 2024-2025 Annual Report
Accurate size data allows emergency managers, planners, and policymakers to better estimate potential exposure, improve evacuation planning, allocate resources, and design infrastructure that accounts for the full spatial footprint of storms. Their database supports:
- Enhanced risk assessments
- Insurance modeling
- Building codes
- Long-term coastal planning.
The analysis found no statistically significant long-term change in size at landfall, However, it did find that:
- Parts of the season—particularly September through November—exhibited larger landfall sizes compared to other months.
- Average landfall size was comparable between the Gulf of Mexico and the East Coast.
- Size did not differ significantly across Category 1–4 storms.
Implications of the Three Studies
SCIPP says that collectively, these three studies highlight the “critical need to better understand tropical cyclone characteristics that directly affect coastal populations.”
The researchers hope to translate their scientific findings into actionable guidance for emergency management, infrastructure planning, and long-term community resilience.
The annual report also contains fascinating findings by leading academic institutions in the region on:
- Hazard mitigation in areas without hazard mitigation planning capabilities
- Heat stress and football-game kickoff times
- Impacts of fiscal decentralization on Disaster Risk Reduction
- Climate migration
- Case studies
- Workshop and intern opportunities
- More
SCIPP’s theme is “Planning for Long-Term Change in a Short-Term World.” To learn more about their excellent work and conferences, or to sign up for their newsletters, visit SouthernClimate.org.
Posted by Bob Rehak on 8/28/2025
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