Winter Weather Awareness Week
December 7-11, 2009
Flood Safety:
...Flooding is the #1 Weather Killer...
Flooding of the Truckee River in downtown Reno in January 2006.
What is the difference between a flash flood and river flooding? Flash flooding occurs within a few hours of the heavy rain event and ends a few hours after it starts. River flooding takes half a day or longer to develop and frequently rivers will remain above flood stage for days at a time.
In Nevada and eastern California, most floods occur from heavy precipitation falling over a period of one or two days, the melting of the snowpack due to periods of warm temperatures, or the combination of heavy precipitation and snowmelt. Damage from flooding can be extreme and can occur within a short period of time after precipitation begins. Recent examples of both urban flooding and river flooding include the 1997 New Years Flood, and the flooding over New Years in 2006. Spring flooding from the melting of an unusually deep snowpack last occurred in 2006.
Flooding problems are sometimes compounded by the denuding of large areas of watersheds by fire during the previous wildfire season. Recent examples of large wildfires include, but are not limited to, the Angora Fire west of South Lake Tahoe, California in June, 2007, the Hawkens Fire in west Reno, Nevada in July, 2007, the Waterfall Fire west of Carson City in July, 2004, or the hundreds of thousands of acres burned by the numerous large wildfires in Humboldt and Elko counties the past few years.
To stay informed about flash flooding or river flooding listen for:
A Flood Watch…
This tells you that there is a potential for flooding or flash flooding. You should remain alert and be prepared to evacuate if a Flood Warning is issued.
A Flood Warning or a Flash Flood Warning…
This tells you that flooding or flash flooding has been reported or is imminent. When a flash flood warning is issued for your area, act quickly to save your life as you may only have minutes to get to higher ground. If advised to evacuate, do so immediately. Go to higher ground or climb to safety. Move to a safe area before access is cut off by flood waters.
An Urban and Small Stream Flood Advisory…
This tells you that flooding of small streams, streets and low lying areas, such as railroad underpasses and urban storm drains, is occurring, but rainfall is not expected to produce a flash flood situation.
The following basic flash flood safety rules should be observed when you see flooding or hear about a flood or flash flood warning…
- Do not camp or park your vehicle along streams and washes, particularly during threatening conditions.
- If you are near a river be aware of water levels and be prepared to take action to move to higher ground if river levels rise.
- Do not enter areas that are already flooded.
- Do not try to cross a flowing stream on foot when the water is at or above your knees.
- If walking or fishing along a river, be aware that erosion from swift running water can cause river banks to collapse.
- Never let your children play around high water, storm drains, viaducts or arroyos.
- If you live near a burn area from a recent wildfire, you may have a higher risk for flash flooding.
- Be especially cautious at night when it is harder to recognize flood dangers.
Nearly half of all flash flood fatalities are auto-related. While driving your vehicle look out for flooding at highway dips, bridges and low areas. Two feet of water will carry away most automobiles. Never attempt to drive over a flooded road. The road bed may be washed out under the water and you could be stranded or trapped. If the vehicle stalls, leave it immediately and seek higher ground. Rising water may engulf the vehicle and sweep it away.
The best advice if you are in a vehicle, turn around, don’t drown.
Street flooding in downtown Reno in January 2006.
Stay informed. You can receive forecasts and immediate notification of warnings anytime of the day or night on NOAA Weather Radio or from NOAA’s National Weather Service homepage at:
www.weather.gov
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www.weather.gov 
