NWS scrutinizes its performance during SC floods
The National Weather Service (NWS) released a report analyzing its performance during the catastrophic flooding that occurred in South Carolina from October 1-5, 2015. The analysis included 40 recommendations based on issues that occurred during the gathering and dissemination of information.
Reported issues included communication between different branches of the NWS and other agencies and organizations, along with the issuing of watches and warnings, the ability of the public to physically receive the information, and their perception of the watches/warnings.
Some issues stemmed from the inability of the public to understand the potential impact from such excessive amounts of rainfall. Individuals had no experience to draw from to comprehend the potentially devastating effects or outcomes of the massive rainfall amounts, and the damage likely to occur from widespread and unprecedented flooding.
The NWS also observed that a portion of the population does not have access to digital media, including smart phones, internet, television and/or radio, making the dissemination and communication of watches and warnings unable to be received, ultimately placing those individuals in danger. Additionally, it was determined that some educational outreach programs conducted by the NWS meant to educate individuals about watches and warnings, along with what actions to take, were not completely understood by the public.
Roles and responsibilities
Forecasters were unclear about the roles and responsibilities related to Regional Operations Center (ROCs) staff members, and were uncertain if the ROCs were staffed twenty-four hours and assumed this to be the case due to the nature of the event and its size.
Difficulties also arose when a liaison deployed to the FEMA Region IV Center, unfamiliar and untrained in the Incident Command System (ICS), had trouble understanding the NWS roles and responsibilities within that setting.
Uncertain & outdated
Other challenges for forecasters included the uncertainty of when to transition watches and warnings regarding flooding types, such as from a flash flood watch/warning to an areal flood watch/warning. As a result, some watches and warnings were allowed to expire and lacked specific impact statements with clear communication.
Another problem encountered was the outdated or nonexistent FEMA flood maps, which would have helped to more clearly delineate impacted areas, highlighting the magnitude and extent of the areal flooding. The NWS was able to utilize real-time mapping tools that were effective for neighborhood-scale decision support.
A well-forecasted event
One area that demonstrated a strong interagency working relationship was between weather forecast offices (WFOs) and the media. Due to frequent training sessions and interactions between local media and WFO personnel, with individuals on a first name basis, communication was strong, easily understood, and able to be re-communicated to the public in a clear, seamless, and rapid fashion. Many people, including the public and the media, felt that the event was well-forecasted in a timely manner.
“But as unusual and extreme as this event was, meteorologists identified and communicated the threat with plenty of lead time. It was an extraordinarily well-forecast flood.” -- Comments made to NWS regarding South Carolina Floods, October 2015.
Overall, the report highlighted gaps and best practices, providing the agency with a guideline that outlines what practices were effective, which ones did not work, and what worked, but could be improved upon.
A summary of the October 1 -5, 2015 South Carolina historic flooding event:
- A frontal boundary that was stalled off the coast
- An upper Low that was slow moving and west of the Carolinas
- Plenty of Atlantic moisture
- Hurricane Joaquin's persistent tropical moisture plume
- Coastal and central regions received 20+ inches of rain
- Widespread flooding/flash floods
- Established flood stages were exceeded at 20 locations
- 19 fatalities, including vehicle entrapments that were swept away by high water
- Damages in excess of $1.49 billion
- 1,500 water rescues in the Columbia region alone
- 49 dam failures to date from the floods:
- 25 C3
- 16 C2
- 7 C1
- 1 Federal dam
- 36 of the dam failures occurred on regulated dams
- Saturated soil and strong winds downed trees and power lines
- 410 bridges and roadway closures for safety, high water, or flooding
C1 – Failure may cause loss of life or serious damage to infrastructure.
C2 – Failure will not likely cause loss of life but may damage infrastructure.
C3 – Failure may cause limited property damage.
Source: South Carolina Department of Health and Environmental Control (SCDHEC)