What Hurricane Florence Was and NOAA’s Role
Hurricane Florence was a long-lived, slow-moving Cape Verde hurricane that affected the U.S. East Coast in September 2018, bringing extreme rainfall, major flooding, and a significant storm surge to the Carolinas. NOAA provided the primary authoritative forecasting and situational awareness for the storm through the National Hurricane Center (NHC), leveraging satellites, aircraft reconnaissance, and global models. This profile summarizes verified details on Florence’s development, forecast and track, impacts, preparedness actions, and lasting lessons for future hurricanes.
Formation and Meteorological Development
Florence originated from a tropical wave moving off the coast of Africa in mid-August 20 Intensification was gradual at first, but once the system reached warmer oceanic conditions and encountered a favorable upper-level environment, it organized rapidly, becoming a hurricane east of the Bahamas on August 31 The storm then moved toward the North Carolina coast while strengthening further, reaching peak sustained winds of 140 mph (Category 4) on September 10 Florence subsequently weakened slightly before making landfall near Wrightsville Beach, North Carolina, on September 14, with sustained winds around 90 mph, before moving slowly inland and stalling over eastern North Carolina, producing catastrophic rainfall.
Genesis and Cape Verde Origins
The tropical wave that became Florence emerged from the African Sahel and crossed the Atlantic in a relatively dry and disorganized state. Over several days, moisture and instability increased in the surrounding environment, allowing deep convection to organize around a well-defined low. As steering patterns shifted, the cyclone curved west-northwest into the Atlantic hurricane main development region, where persistent warm sea surface temperatures supported further organization into a named storm and then a hurricane.
Peak Intensity and Landfall Details
At its peak on September 10, Florence was a small-core Category 4 hurricane, with central pressure near 937 mb and maximum sustained winds of 140 mph Located over the open Atlantic, it did not significantly impact land at that intensity Florence then tracked steadily toward the North Carolina coast, gradually weakening due to increasing southwesterly shear and slightly cooler waters Shortly before landfall on September 14, reconnaissance indicated sustained winds near 90 mph, with a large and asymmetric wind field that contributed to widespread damage across coastal and interior regions.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Formation (Tropical Wave Exit) | Mid-August 2018 off the African coast | NOAA/NHC Best Track |
| Named Storm Date | August 28, 2018 | NHC Public Advisories |
| Hurricane Intensification | August 31, 2018 | NHC Best Track |
| Peak Intensity (Category 4) | September 10, 140 mph, 937 mb | NOAA/Aircraft Recon + Satellite |
| Landfall | September 14, near Wrightsville Beach, NC, ~90 mph | NHC Final Report |
| Post-Landfall Behavior | Slow northward drift, stalling over eastern NC | NOAA Analysis & Models |
| Central Pressure at Peak | Approximately 937 mb | NOAA Aircraft Data |
| Storm Type | Cape Verde hurricane, large asymmetric wind field | Synoptic Review |
Forecasting, Track, and NOAA’s Prediction Timeline
NOAA’s forecasting of Florence demonstrated both the advances in hurricane prediction and the inherent challenges of slow-moving storms. Early guidance correctly identified the general westward track toward the North Carolina coast, but there was notable uncertainty in the exact landfall location and timing of the slowdown. As Florence approached the coast, ensemble spread decreased, and high-resolution models increasingly indicated a stalling pattern near the coast. The result was a well-forecast track but an extended duration of life-threatening conditions over parts of the Carolinas, emphasizing the importance of communicating potential extremes in rainfall and storm surge rather than focusing solely on the precise landfall point.
Key Forecast and Track Highlights
- Multi-day track guidance consistently showed a western trajectory into the North Carolina coast, with reasonable accuracy in the 5-day outlook.
- Ensemble forecasts illustrated increasing uncertainty in landfall location and forward speed as the cyclone neared the coast.
- NOCC (NOAA’s National Centers for Coastal Ocean Science) provided storm surge guidance that supported coastal inundation forecasts used by emergency managers.
- Rainfall forecasts highlighted the potential for historically wet conditions, which were realized in the prolonged stalling event.
Documented Impacts and Verified Consequences
Florence produced extreme rainfall totals exceeding 30 inches over large portions of North and South Carolina, with a peak observed near 37.5 inches in North Carolina. The slow motion of the hurricane allowed rainbands to train over the same areas for extended periods, overwhelming rivers, creeks, and drainage systems. Coastal storm surge, enhanced by the storm’s broad wind field and near-coast stalling, led to significant inundation along the immediate coastline. Strong winds and widespread flooding caused prolonged power outages, damaged infrastructure, and resulted in fatalities. Agricultural losses were substantial, and river flooding persisted for weeks in some basins.
Verified Impact Summary
| Metric | Estimate or Range | Context |
|---|---|---|
| Direct fatalities (U.S.) | Approximately 24–42 deaths (final report range) | Includes direct and indirect causes where verified |
| Peak Rainfall | Over 37 inches in North Carolina (mountains) | Observed by NOAA/NWS cooperative networks |
| Storm Surge | 4 to 9 feet in coastal areas | Post-storm survey and model analysis |
| Power Outages | Hundreds of thousands at peak; many days in some areas | Utility reports and NOAA Event Record |
| Agricultural Losses | Estimated hundreds of millions of dollars | State and federal agency assessments |
Preparedness, Response, and Public Communication
NOAA and the broader weather enterprise provided a range of products and guidance before and during Florence, including tropical cyclone forecasts, storm surge watches/warnings, river flood advisories, and excessive rainfall outlooks. Emergency managers used Saffir-Simpson Hurricane Wind Scale information and rainfall-driven flood guidance to issue evacuations and sheltering recommendations. Clear communication on the risks—particularly rainfall flooding and storm surge—helped reduce preventable impacts, although challenges remained in reaching all vulnerable populations. Post-storm evaluations emphasized the value of timely, consistent messaging and the need to account for compounding hazards (wind, rain, surge) in public communications.
Preparedness Actions and Guidance
- Advance evacuation orders for coastal zones based on NOAA storm surge guidance.
- Public messaging on life-threatening rainfall flooding and inland river rise.
- Coordination with FEMA, state and local officials for sheltering and resource staging.
- Use of NOAA aviation and satellite data to monitor inner-core structure and intensity changes.
Scientific and Operational Takeaways
Hurricane Florence underscored several enduring themes in hurricane science and operations: the critical need to communicate compound and secondary hazards (rain, surge, wind), the importance of probabilistic forecast guidance, and the value of aircraft reconnaissance in refining track and intensity forecasts. Continued improvements in model resolution, data assimilation, and forecast-based decision support have strengthened the ability to anticipate stalling events and extreme rainfall. For the public, the lasting lesson is to plan for multiple hazards and heed evacuation and sheltering guidance well before a storm’s closest approach.
Key Takeaways
NOAA’s monitoring and forecasting were central to the trajectory and impact assessment of Hurricane Florence. Below are verified highlights for enduring reference:
- Florence formed from a tropical wave in mid-August and became a Cape Verde hurricane.
- Peak intensity reached Category 4 on September 10, with a central pressure near 937 mb.
- Landfall occurred on September 14 near Wrightsville Beach, NC, with ~90 mph winds.
- The storm’s slow, stalling motion produced extreme rainfall and major river flooding.
- Post-event analyses confirmed the value of multi-day track guidance and the need to communicate rainfall and surge risks together.