Flash Flood Watch: Thunderstorms, heavy rainfall possible

ST. GEORGE The National Weather Service in Las Vegas has issued a “flash flood watch” in effect through Saturday evening for portions of northwest Arizona and southern Nevada with the southern tip of Utah, including St. George, included in the map denoting affected areas.

A high moisture content remains in place in the atmosphere across the area. Any stronger or slower moving thunderstorms could unleash heavy rainfall in a short period of time. Rainfall totals of 1-2 inches in an hour or less, with locally higher amounts, are possible in some cases.

Dots indicate the area subject to the flood watch, Aug.,1, 2015 | Photo courtesy of National Weather Service, St. George News | Click image to enlarge
Dots indicate the area subject to the flood watch, Aug.,1, 2015 | Photo courtesy of National Weather Service, St. George News | Click image to enlarge

Affected Areas

  • Northwest Arizona: Lake Mead National Recreation Area, northwest deserts and northwest plateau
  • Nevada: Lake Mead National Recreation Area, Las Vegas Valley, Lincoln County, northeast Clark County, Sheep Range, southern Clark County, Spring Mountains-Red Rock Canyon, western Clark County and southern Nye County
  • Utah: St. George area, bordering the affected areas, may experience similar impacts

Impacts

Roads could be closed due to water flowing over them, as well as mud and rocks washing into them. Roadway pavement may be washed away. Some dirt and secondary gravel roads could be washed out. Rapid rises in washes could also occur leading to flash flooding downstream. Any burn areas, such as the Carpenter 1 Burn Area on Mount Charleston in Nevada, could also see debris flows take place if heavy rain falls on or runs onto the burned landscape.

 Precautionary, preparedness actions

Remain alert for flooding even in locations not receiving rain. Dry washes, streams and rivers can become raging killer currents in a matter of minutes, even from distant rainfall.

Move to higher ground now. Act quickly to protect your life.

Do not drive your vehicle into areas where the water covers the roadway.  The water depth may be too great to allow your car to cross safely.

Turn around. Don’t drown.

The National Oceanic and Atmospheric Association and the National Weather Service offer safety rules for flash flooding:

  • Flash flooding is a very dangerous situation
  • Flash flood waves, moving at incredible speeds, can roll boulders, tear out trees, destroy buildings and bridges and scour out new channels. Killing walls of water can reach heights of 10 to 20 feet. You will not always have warning that these deadly, sudden floods are coming. When a flash flood warning is issued for your area or the moment you first realize that a flash flood is imminent, act quickly to save yourself. You may have only seconds.
  • Most flood deaths occur in automobiles. Do not drive your vehicle into areas where the water covers the roadway. Flood waters are usually deeper than they appear. The road bed may not be intact under the water. Just one foot of flowing water is powerful enough to sweep vehicles off the road. If the vehicle stalls, abandon it immediately and seek higher ground. Rapidly rising water may engulf the vehicle and its occupants and sweep them away
  • Do not hike rivers and especially slot canyons while flash flood warnings are in place
  • Do not hike alone and always tell someone where you and your buddy and others are going
  • Get out of areas subject to flooding, including dips, low spots, canyons and washes
  • Avoid already flooded and high velocity flow areas. Do not try to cross a flowing stream on foot where water is above your knees
  • Be especially cautious at night when it is harder to recognize flood dangers
  • Do not camp or park your vehicle along streams and washes, particularly during threatening conditions

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Copyright St. George News, SaintGeorgeUtah.com LLC, 2015, all rights reserved.

 

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