SWAW, Day 3: Floods and Flash Floods

It's Severe Weather Awareness Week in MN and WI, which means its time to start going over what everything is again and what precautions to take when severe weather strikes. The Storm Prediction Center is now charting out a possibility of strong to severe storms on Thursday for the Arrowhead of MN stretching down to the STC area, with the main threats being damaging winds and hail, and a Slight Risk of Severe Storms Friday and Sunday around the area (we'll have more on the threat later today), so now is as good as time as any to relearn what we do in summertime, like how we have to relearn the winter warnings (and how to drive) in the winter. Remember, throughout the summer we'll cover it the best we can on Facebook and Twitter. Today's topic, brought to you by the National Weather Service, is Floods and Flash Floods -- I have included the watch, warning, and advisory criteria at the beginning, followed by the information that the NWS issued for today's topic.

Floods and Flash Floods

Watches...
Flood Watch... Atmospheric and hydrologic conditions are favorable for long duration areal or river flooding.
Flash Flood Watch... Atmospheric and hydrologic conditions are favorable for short duration flash flooding and/or a dam break is possible.

Warnings...
Flood Warning... Long duration areal or river flooding is occurring or is imminent, which may result from excessive rainfall, rapid snow melt, ice jams on rivers, or other similar causes.
Flash Flood Warning... Excessive rainfall producing thunderstorms have developed, leading to short duration flash flooding. A warning may also be issued if a dam break has occurred.

Advisories...
Urban and Small Stream Advisory... Thunderstorms have produced heavy rainfall that may result in ponding of water on roadways and in low-lying areas, as well as rises in small stream levels, none of which pose an immediate threat to life and property.

On a National Level... Floods claim nearly 200 lives annually, force 300,000 persons from their homes, and result in property damage in excess of 2 billion dollars. Characteristically, 75 percent of flash flood deaths occur at night with half of the victims dying in their automobiles or other vehicles. It may be difficult to believe, but many deaths occur when persons knowingly drive around road barricades indicating the road is washed out ahead.

Last Year in Minnesota and Wisconsin... Wisconsin had one flood-related fatality last year, late on June 12th near Wales, when a man drove into a flooded area. Minnesota also had one flood-related fatality in 2008. This occurred on June 12th near Oakland when a man drove into a flooded area

In 2007... Disastrous flooding struck southeast Minnesota and southwest Wisconsin on August 18th and 19th. Eight people died that weekend... 7 in Minnesota and 1 in Wisconsin. Most deaths occurred in vehicles. A statewide record for 24-hour rainfall was set in Minnesota when 15.1 inches fell 1 mile south of Hokah.

Are You Prepared? Assume a thunderstorm produces 6 inches of rain in less than 6 hours time near your community. Storms of this magnitude or greater occur several times each year in the U.S. Would you know what action to take to protect yourself and the people who depend on you for safety? After a major flood event, one of the most common quotes from the survivors of the flood is the expression they did not believe it could happen to them or in their community.

Before the Flooding... There is nothing anyone can do to prevent the occurrence of flash flood producing rainfall. However, by striving for sound flood plain zoning, developing an emergency action plan in advance of the disaster, purchasing flood insurance at least 30 days before the flooding, and being aware of the dangers associated with extremely heavy rainfall and flooding, there is a chance of decreasing the death toll and property damage that results from flash flooding.