Saturday, December 26, 2015

Simulated Flash Flooding Could Save Lives



Photo Credit: Cody Duty - Houston Chronicle - AP
A follow-up post to the original, "The Future of Flash Flood Warnings."


Flash flooding has claimed scores of lives across the U.S. in 2015. Twenty-six major disaster declarations have been made in the name of FLOODING. As heavy downpours increase in frequency, millions of people will be susceptible to this rapid impact natural disaster. El Nino may also contribute to an increase in events in the next several months for parts of the country.
The New Year's Flood in the Mississippi River
Sandbagging efforts along MS River - Photo: Michael Kelley
Valley is the most recent example of how a single event can take lives and destroy property with very little in the way of time to react.  You can prepare people as much as humanly possible but until it impacts them specifically, you are sort of speaking and dealing with the unknown. Our region is no stranger to extreme river flooding and flash flooding (urban) events. Rather than looking back, I want to introduce you to the technology and the advancements coming our way to help get the warnings out faster in these type of events, specifically flash flooding.
In 2012, Project FLASH began simulating real-time flash flooding events using hydrological model data and high resolution rainfall observations.
Click to Enlarge
"The primary goal of the FLASH project is to improve the accuracy, timing, and specificity of flash flood warnings in the US, thus saving lives and protecting infrastructure." -Flooded Locations and Simulated Hydrographs website
Most of us recognize or at least have heard of the Spring 2015 flooding in OK/TX including the Red River. To the right is a before and after of the flooding. It was not just the river bottoms that were impacted.  The very first photo in this blog is just one example of the urban areas that were impacted and where lives were lost. Streets covered in feet of water leaving motorists stranded on a major interstate around Houston.
More recently we watched a well-forecast event unfold in the Carolinas thanks to an off-shore Hurricane named Joaquin. As the rain began to fall, I started archiving FLASH data to see just how this new simulation would perform alongside the outcome.


This particular animation I compiled displays the simulated surface water flow (normalized by drainage area) drawing from MRMS radar-only rainfall rates at a 5 minute resolution. Not only is it visually enlightening, more importantly, it makes huge strides in improving short-term forecasting and flash flood probabilities. One important result is that the image shows what forced flash flooding would look like unfolding with the rainfall rates and totals being observed on radar. This can help forecasters/meteorologists put out longer lead times for Flash Flood Warnings...even on a small scale. In fact, many flash flood events are small scale in nature compared to a river flooding or inland flooding event, and why it can be so difficult to get ahead of. An added benefit to modern day warnings is that they are constructed by using polygons rather than entire county borders. Meteorologists can warn just a few miles of housing/businesses that sit along a creek bed rather than alerting an entire county where a majority of residents would otherwise be unaffected.

The next animation is a look at the Paducah, Kentucky flash flooding event that called for multiple water rescues at sunrise on July 7, 2015.


In a two-hour period of time (4-6 AM), 6 inches of rain fell on one of the most flood prone areas in town, Perkins Creek. Public reports of flooding were hard to harvest since many were sleeping. Early risers encountered the waters as the Flash Flood Warning was issued around 5:15. FLASH was able to force the accumulating rain on radar into a simulated hydrograph showing the likelihood of flash flooding as the event was ongoing in the following animation.
Word is that some of this technology may be introduced into forecasting in a more official capacity within the next year or so. Minutes matter when it concerns getting the public to respond to flash flooding. Minutes may be all they have to find higher ground. Minutes could very well be what we gain in lead time to saves lives and evolve the future of flash flood warnings.




1 comment:

  1. Jennifer, Thank you for all of your hard work and dedication. I love your post.

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