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EACHUS: flash flood warning changes a step, not a solution

3 months 1 week 1 day ago Tuesday, February 18 2020 Feb 18, 2020 February 18, 2020 10:34 AM February 18, 2020 in Weather
Source: WBRZ Weather

FLASH FLOOD WARNING! (But, you don’t have to worry about this one)

IN 2020, THE National Weather Service (NWS) is implementing Impact-Based Flash Flood Warnings. The goals are to provide easily readable information and to improve public response. However, like most weather messaging, some significant efforts will be needed to avoid confusion.

Prior to Impact-Based Flash Flood Warnings (FFWs), all FFWs triggered Wireless Emergency Alerts (WEAs) to mobile devices. WEAs are those automatic alerts, built into phones, with that unmistakable and startling alarm. These are not to be confused with push notification from weather apps such as WBRZ WX. With over 12,000 FFWs issued each year, public perception is that the NWS over-warns on FFWs. State and federal officials report many complaints about WEAs that result in minimal impact to people and property.

In the Impact-Based format, FFWs will contain bullet points of clearer information about the flash flood, including the source of the information and a description of the impacts along with a “damage threat” tag. Perhaps most importantly, these damage threat tags will mean that only FFWs tagged “considerable” or “catastrophic” will trigger a WEA. Problem solved, right? Not so fast…

On one hand, this effort should be applauded for attacking perceived false alarms. However, the change is likely to create substantial confusion regarding the FFW product. Understand that while the number of WEAs will indeed be reduced, there will not be any changes (aside from normal annual variance) to the number of FFWs issued.

This tasks the WBRZ Weather Team, and other communicators, with differentiating between different levels of FFWs. You must wonder, why issue a FFW if “considerable” or “catastrophic” impact is not expected? What defines a FFW that does not need a WEA?

Certainly, there are weather criteria that constitute the issuance of a FFW. From a meteorological standpoint, the criteria make sense. From a communication standpoint, criteria routinely create communication problems.

In flood prone areas of the Gulf South, there are dozens of annual instances of street or poor drainage flooding. These situations most often arise from stationary summer thunderstorms that dump a fast two to three inches of rain. There are certain low-lying areas that always hold water. Even in these cases, it is often standing water that is ankle to knee deep, certainly capable of stalling a vehicle, but unlikely to kill. Flood Advisories (FA) are often adequate to remind people not to drive across flooded roads. In northern areas with extensive topography, the hydrological response is more rapid and drastic. Much lower rain amounts can lead to far greater water inundation and streams can quickly become rushing rivers. This type of situation usually warrants a FFW. In the Gulf South, rain need to be particularly intense and streams need to be extremely aggravated to produce this type of scenario.  Weather alerts should be clear and concise, with minimal room or need for interpretation. The criteria for flooding are simple, and right in front of us. The flooding is either life threatening, or it is not. In an Impact-Based system, the threat to life and property is the impact.

A stepped structure such as FLOOD ADVISORY –> FLASH FLOOD WARNING –> FLASH FLOOD EMERGENCY (accompanied by WEA) would be a prudent solution. Unfortunately, the forthcoming change is just one degree off from this idea, with a two-tiered FFW versus a separate and more significant product. Instead of being more liberal with FAs, more conservative with FFWs, and reserving the Flash Flood Emergency for life threatening scenarios, the NWS is just creating a product within a product.

People now need to decipher a FFW that is “considerable” or “catastrophic” versus one that is not. Why are two different situations triggering an alert with the same name? Why keep the FA product for non-life threatening flooding if there is some level of FFW that is also not life threatening? While meteorologists may be able answers these questions (to an extent), can everyone else?

Assume somebody receives a WEA for a FFW and turns to their preferred source for more information. The source explains the life-threatening nature of the situation. At another time in the future, that person also hears about a FFW for their favorite source but does not receive a WEA. Without significant attention to message, which is not often given under duress, how is that person to know the difference between this FFW and the last? Would they not assume this is also a life threatening situation, respond accordingly, and once again be victim of an overabundance of FFWs? Perhaps the opposite could be true. A person will be affected by numerous FFWs before one actually warrants a WEA. Would they then ignore the situation and then be in serious danger?

To recap, the National Weather Service will continue to issue Flash Flood Warnings and Flood Advisories. These alerts will still come through on NOAA Weather Radio, WBRZ and the WBRZ Weather App. In general, these situations will encourage us to avoid high water areas such as creeks and streams and not to drive on flooded roads. However, only the most significant, and potentially life-threatening flash flood warnings will trigger the Wireless Emergency Alert system on mobile phones. These situations will require immediate, life-saving action.

We want to help. If you have any questions, contact the WBRZ Weather Team, weather@wbrz.com.

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