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Public Information Statement
National Weather Service Little Rock AR
600 AM CST Mon Mar 01 2021

...Todays Topic for Severe Weather Awareness Week is Flooding...

The National Weather Service, in cooperation with the Arkansas 
Department of Emergency Management, has proclaimed the week of 
February 28th through March 6th as Severe Weather Awareness Week 
in Arkansas.  

A different topic will be discussed each day, and todays topic is 
flooding. 

High water usually comes in two phases: flash flooding and river
flooding. 

Flash floods usually occur within six hours. The rate of 
rainfall exceeds the rate of runoff; that is, rain falls faster 
than it can be carried away. Because water has nowhere to go, it 
covers roads and fills small streams and creeks.

Flash flooding is usually caused by very slow-moving thunderstorms, 
or thunderstorms that repeatedly move over the same areas. 

Urban settings are especially prone to flash floods due to large 
amounts of concrete and asphalt surfaces that do not allow water to 
penetrate into the soil. 

Places surrounded by steep, hilly terrain are also susceptible to 
flash floods due to rapid runoff /water moving downhill at elevated 
speeds/ into streams and creeks. 

In the last 30 years, flash flooding was the deadliest thunderstorm 
hazard, and caused more fatalities than tornadoes and lightning. 
There are an average of 80 to 90 fatalities annually due to flash 
floods across the country. 

Roughly half of flash flood deaths occur when people try to drive 
through flooded areas. Moving water two feet deep is sufficient to 
carry away most vehicles, even pickup trucks and sport utility 
vehicles. 

In 2020, despite well above average rainfall and flash flooding 
at times, high water led to no fatalities.

The most deadly flash flood event in recorded state history 
happened in 2010. The Little Missouri River /a flashy 
tributary/ rose more than 20 feet during the predawn hours of June 
11th. This was after more than half a foot of rain. Campers at the 
Albert Pike Recreation Area /Montgomery County/ were awakened to 
raging water, and 20 people drowned.

River flooding is a longer term event than flash flooding, and can 
last for several days or even weeks. Water from flash flooding 
eventually makes its way into rivers, with excess liquid flowing 
into nearby towns, fields, etc. 

Rivers are most likely to overflow when the soil is saturated, and 
runoff rates are high, and/or water levels are elevated prior to a 
heavy rain event. 

When rivers spill over, it can be devastating. Water can overtake
homes, businesses, and thousands of acres of cropland.

For much of 2020, several tributaries were high including the Black, 
Cache, Ouachita, and lower White Rivers. Even so, any flooding was
generally minor, and the rivers mostly behaved.

...Flood Safety Rules...

You should know which places in your area are prone to flooding, and 
avoid these places in times of rising water. 

Do not attempt to cross flowing streams while driving or on foot. 

If flood waters are between you and your destination, the National 
Weather Service wants you to remember a simple slogan: Turn Around - 
Dont Drown. 

Outdoor activities are very popular in Arkansas. If you enjoy camping 
or similar recreation, be especially careful if you spend the night 
near streams. A thunderstorm miles upstream from your location could 
produce enough rain to cause flooding, even if it is not raining much 
where you are. 

Never allow children to play around high water, storm drains, and 
culverts.

&&

For a list of all the tornadoes and other significant weather events 
that occurred in 2020...

https://www.weather.gov/media/lzk/StormsOf2020.pdf

$$

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