Governor Proclaims May 10-14 Wyoming Flood Awareness Week
by National Weather Service
May 10, 2010
Governor Freudenthal and the National Weather Service have proclaimed May 10 through 14 as Wyoming Flood Awareness Week. NWS and emergency officials encourage people to become more alert to the dangers of flooding even during times of drought. The awareness week is intended to promote flood safety and preparedness, understanding of the different flood hazards that can impact Wyoming, and improved monitoring of hydrologic conditions.
The transition to warmer temperatures in May often signals the majority of mountain snowmelt. Even during years of average or below normal snowpack, a quick warm-up can rapidly melt snow leading to flooding of mountain streams and tributaries. Flooding from snowmelt is becoming more accurately forecast, providing officials more lead time to prepare for rises along these waterways.
Flash flooding, typically the result of intense thunderstorms, is a different matter. Even during drought years, an intense thunderstorm can quickly inundate a drainage basin of a small stream or river, causing flash flooding in a matter of an hour, if not minutes. Historical flash flooding of Cheyenne on August 1, 1985, and of Kaycee on August 27, 2002, are two examples of heavy rain falling within small drainage basins resulting in rapid water rises. NWS officials are also urging residents of cities and towns to be prepared for the quick water rises in urban areas that can occur after intense rainfall, even if the rain only lasts 20 or 30 minutes.
"The Casper flash flood of last July 3 was a classic example of what can occur in an urbanized area following an intense, heavy rainfall. Concrete, asphalt, buildings, and other structures are obviously poor water receptors, so rapid water run-off produced flash flooding within 30 minutes after the rain began," said Chris Jones, warning coordination meteorologist at the Riverton NWS office. "Following these types of heavy rain storms, we hear of people trapped in or abandoning their vehicles after attempting to navigate low water crossings. The best course of action in that instance is to turn around and find a safe alternative route, or to wait at a safe location on higher ground."
During the awareness week, NWS and emergency officials are reminding people to never swim, play, or walk through flooded areas and to avoid camping near streams or dry washes if there is a threat of flooding. Officials say that even if rain did not fall at your location, headwaters in the mountains may have received heavy rain which could cause rapid water rises downstream. Campers and hikers should consider taking along an All Hazards NOAA Weather Radio receiver, which provides easy access to current forecasts and alert information for weather and man-made disasters.
For more information about Wyoming Flood Awareness Week, visit the National Weather Service website at http://www.crh.noaa.gov/cys/floodweekWY.php?wfo=riw