Understanding flooding in all its forms

We've come to the end of July, and I think it's safe to say that we've dealt with more than our fair share of flooding in the Tri-State this summer. From mid-June through the month of July, numerous flash floods inundated roadways and invaded basements from Long Island to the Hudson Valley and many neighborhoods in between. We've also seen flooding on creeks and streams, and in mid-July, even the Connecticut River overflowed its banks. All of these events have one thing in common- too much water. But flooding manifests in plenty of different ways, requiring very different actions to prepare and protect. Let's break them down. 

Flash flooding, as the name implies, happens very quickly and usually impacts a small geographical area, like a few city blocks or a small creek. Flash Flood Warnings are issued when the threat is imminent or when the flooding has already started to happen. Since flash floods happen quickly, drivers are sometimes caught unaware or unprepared for the deluge, leading them to get stuck, like the driver below. 

But when a Flood Warning is issued, the flood potential is likely to last much longer. And, you can literally see it coming; when the word "flash" is not attached to the warning, we're talking about a type of flooding that creeps up more slowly, usually over a period of hours. Flood Warnings are most commonly issued for waterways such as rivers and creeks, because stormwater from nearby streets filters into these bodies of water over the course of hours or days, often long after the rain has stopped falling. 

And then there's coastal flooding, which can happen for a number of reasons. Storm surge is the most common source of major coastal flooding in the Tri-State. It can come from a storm like a Nor'Easter, like the record-breaking blizzard in 2016, or a tropical storm like Sandy in 2012. This aerial view of Mantoloking from the National Weather Service shows just how devastating coastal flooding can be.

High tide sometimes causes minor coastal flooding in the NYC area, especially during the New Moon and Full Moon phases. In fact, this type of flooding is possible tonight at high tide. 

As discussed back in my May 1st blog post, flooding events, especially flash flooding, are likely to happen more often in our warming world. In the city and surrounding area, we also have a lot of impervious surfaces, exacerbating runoff and making flooding even more common. As July comes to a close, it might surprise you to learn that Central Park's precipitation total is less than an inch above the monthly average, with 5.34" to date, and not nearly enough to break a record.

 It doesn't take a historic amount of rain to cause major problems in the Tri-State. With summer downpours getting heavier, it's important to be prepared for the potential for flooding, even on a "normal" summer day. NOAA provides tips for flood awareness and safety on the National Weather Service's website.