Note: March 12 through 18 is Flood and Wildfire Safety Week in Colorado. This is the second article in a series on safety and preparedness. See Sunday's overview here.
In September 2013, heavy rain fell over a large area of the foothills south to the Pikes Peak Region, resulting in flash flooding. Much of the water that fell across northeast Colorado eventually ended up in the South Platte River, with major river flooding occurring from Greeley to the state line.
River flooding can result from heavy rain during the summer and from rapid snow melt or thunderstorm rain combining with runoff from melting snow.
Flash flooding refers to a dangerous sudden rise in water in an urban area, in a canyon, or along a creek or wash over a normally dry land area. Flash floods results from heavy rainfall, sudden breaks in river ice jams, and dam or levee failures. Flash floods can occur within a few minutes or hours, and can move at surprisingly high speeds, striking with little warning. Flash floods are quite destructive because of the force of the moving water, and the debris that accumulates in flood waters, such as trees and boulders, which can destroy roadways, bridges and buildings.
Another complication in Colorado is the serious flooding that can result when heavy rain falls on recently burned areas. Anyone living downstream from a recently burned area should be aware of the changed conditions, which result in much faster, turbulent, debris and ash clogged waters from the burned area.
The National Weather Service will discuss flood and flash flood potential in daily hazardous weather outlooks and in the graphical weather story on National Weather Service websites.
On days with a high threat for flooding, you may hear of a Flash Flood or Flood Watch, which means that flash flooding or flooding is possible within the watch area.
A Flood Warning, which means that flooding is imminent or has been reported along a river.
A Flash Flood Warning, which means that flash flooding has been reported or is imminent. When a Flash Flood Warning is issued for your area, act quickly. If advised to evacuate, do so immediately. Go to higher ground or climb to safety before access is cut off by flood waters. Go Up, Not Out.
Nearly half of all flash flood fatalities are vehicle related. Do not enter a flooded roadway, instead Turn Around...Don't Drown. In rapidly rising waters, backing up away from water would be safer. One to two feet of water will carry away most vehicles, and you also cannot tell if the road is damaged beneath the water.
More information on flooding hazards can be found on the National Weather Service Flood Safety page at:
Colorado Flood Safety and Wildfire Awareness Week continues through this Saturday.