AccuWeather.com

By Heather Buchman, Meteorologist

Jun 13, 2010; 8:02 AM ET

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This image made from television courtesy of KATV shows The Albert Pike Recreation Area, a 54-unit campground in the Ouachita National Forest, in Ark. on Friday June 11, 2010 after flash floods swamped campgrounds along a pair of southwestern Arkansas rivers early Friday. (AP Photo/Courtesy KATV)

There were many factors that contributed to the deadly flooding that unfolded across western Arkansas late this past week. While it was a storm system that caused heavy rain to inundate the region, there were many non-weather-related influences that made the event so deadly.

The Weather Influences

A slow-moving storm system in the upper levels of the atmosphere was the culprit behind the heavy rain that inundated western Arkansas Thursday into early Friday. This system first started sparking heavy thunderstorms that caused flooding southern Texas, including San Antonio, Tuesday of this past week.

This system had a good deal of tropical moisture associated with it, which provided plenty of fuel for the thunderstorms and allowed them to become as heavy as they did.

Wednesday into Thursday, the system continued sparking heavy thunderstorms as it slowly trekked northeastward through Texas and into Arkansas. More localized flooding resulted along the way.

The worst of the system and its associated thunderstorms hit western Arkansas Thursday night. Thunderstorm activity was able to increase over this area Thursday night as the atmosphere surrounding the storm system cooled and the air within the system remained warm.

This contrast between cool air above the system and warm, humid air within it created a more unstable environment conducive to thunderstorm development. The heavy and slow-moving nature of the thunderstorms is what contributed to the flooding.

The thunderstorms unleashed 6 to 7 inches of rain in less than 24 hours across western Arkansas, including the Albert Pike Recreation Area in Montgomery County where at least 16 people were killed.

Non-Weather-Related Factors

While the rain that fell during this event was heavy, it wasn't necessarily enough on its own to cause such deadly flooding.

There are many parts of the southern U.S. that receive 6 inches of rain or more in a short period of time. While flooding does often result after that much rain falls, it is rarely this significant and deadly.

The outside factors that made this such a deadly event were the topography of the area and the fact that it occurred at night while people camping or staying in cabins at the Albert Pike Recreation Area were sleeping.

The recreation area is located along the Little Missouri River in a valley surrounded by the mountainous terrain of Ouachita National Forest.

Runoff from the heavy rain flowed down mountainsides and into small creeks in streams that fed into the Little Missouri River. In response, the river rose nearly 20 feet in just a few hours at the nearby town of Langley.

According to the Little Rock National Weather Service Weather Forecast Office, the Little Missouri River crested just higher than 23 feet, setting a new record. Records have been kept there since 1988.

Tragically, this all happened at night after many people had already gone to sleep unaware of the danger. A flash flood warning was issued around 2 a.m. Friday.

Weather for Ongoing Rescue Efforts

Fortunately, stormy weather is expected to stay well north of the recreation area this weekend, allowing rescue crews to continue searching for survivors.

The downside is that rescuers and any survivors will have to contend with searing heat the rest of the weekend as temperatures rise well into the 90s and humidity sends AccuWeather.com RealFeel temperatures into the 100s.

The chance for showers and thunderstorms will increase across the area early next week.

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