Parts of Louisiana, Mississippi, western Tennessee and Kentucky are literally underwater due to flooding the began in earnest late Tuesday night from torrential, repeated rainfall. On the national news Wednesday night, an affected resident outside Shreveport reflected that, “I didn’t know it was going to happen so quickly”. Comments like this always give me pause to think about the effectiveness of the warning process of the weather enterprise when it comes to flooding.
Flash flood watches first began popping up in Louisiana early Tuesday morning and now they’ve been extended into the weekend.This map shows the active watches as of Thursday afternoon in green.
Unlike their severe thunderstorm and tornado counterparts, flash flood watches are often issued a day or two before a storm event. In some ways, this might lessen their perceived importance or impact by the public. It can also lead to confusion as some automatic crawls on TV begin running when the watch is issued, even though it doesn’t go into effect for many hours later. The intent is to give the public a day’s notice to prepare because for some, moving to higher ground poses many challenges. Also, flooding tends to cover a wider area so it will likely have a more substantial impact than say a tornado outbreak. The latter, while tragic in consequence, generally strikes more sporadically and is more localized.
Yet the public may not be able to parse this out clearly and given the brevity of some local newscasts, the local broadcast meteorologist might not get the time needed to fully explain the impact and timing. Additionally, a flash flood watch isn’t just issued days before an event, it’s slated to last for several days. Take for example the wording in the first watch issued in hard-hit Shreveport Tuesday morning: “A flash flood watch remains in effect from 4 pm this afternoon through Thursday afternoon.” Not everyone getting this message may be able to understand fully that its not going to rain the entire two-day period.
So I circle back to that news sound bite I referenced at the beginning. The watch was in place, it did indicate that heavy rain would lead to flooding that could lead to nearly a foot of rainfall. It may seem very clear to the weather enterprise that adequate warning was given, but as usual, I ask – are people getting a real sense of what could happen and do they understand the messaging?
Once the heavy rainfall begins to occur and its obvious that rainfall rates will lead to flooding, warnings are issued, but for some it might be too late to move to higher ground. The time to plan for that is when the watch is issued, but I wonder if that message truly comes across with the proper emphasis. Unfortunately, these episodes generally tend to benefit those in the region set to get the flood impact next. Once they see what is actually occurring, they tend to take the threat more seriously.