UPDATED: Significant weather alert warns of hail and thunderstorm over Lake Powell

File photo, St. George News

Update 9:42 p.m. Flash flood warning for southeastern Washington County added.

Update 4:10 p.m. Significant weather advisory for San Juan and Kane counties added.

ST. GEORGE – Thunderstorms and rain moving through parts of Southern Utah Saturday have led to the issuance of several weather advisories.

Hildale/Colorado City flash flooding

A flash flood warning has been issued for southeastern Washington County in southwestern Utah in effect until 11:00 p.m MDT.

At 9:01 PM MDT, Doppler radar indicated thunderstorms had produced rainfall of approximately 1 inch since 8 pm over Hildale and the drainages above Hildale.

Some locations that will likely experience flooding include Hildale and Colorado City, including along Short Creek and the washes that feed into Short Creek.

Hail and thunderstorms move through Lake Powell

Shaded area denotes region subject to significant weather alert. Map generated 3:57 p.m. MST, Aug. 12, 2017 | Map courtesy National Weather Service, St. George News

The National Weather Service has issued a significant weather advisory for south central San Juan and east central Kane counties until 4:45 pm MDT.

At 3:54 PM MDT, National Weather Service Doppler radar indicated a strong thunderstorm 9 miles southwest of Halls Crossing, or 48 miles northeast of Page moving southeast at 20 mph.

Penny to nickel size hail and winds in excess of 40 mph will be possible.

The weather advisory affects Glen Canyon National Recreation Area.

If on or near Lake Powell, get out of the water and move indoors or inside a vehicle. Lightning can strike out to 10 miles from the parent thunderstorm. If you can hear thunder, you are close enough to be struck by lightning. Seek shelter and do not be caught on the water in a thunderstorm.

Garfield county flash flooding

Flash flood warning map for the warning issued Saturday, August 12, 2017 | Map courtesy of the National Weather Service, St. George News

The National Weather Service in Salt Lake City has issued a flash flood warning for west central Garfield County in southern Utah until 3:15 p.m. Saturday.

At about 12:20 p.m. Doppler radar indicated a line of thunderstorms producing heavy rain over west central Garfield County. One to two inches of rain have already fallen in the last hour. Flash flooding is expected to begin shortly.

Drainages in this warning include Panguitch Creek, South Canyon, Pass Creek and associated drainages. SR-143 east of Brian Head to the junction with SR12 near Panguitch is included in this warning.

Some locations that will experience flooding include Panguitch and Hillsdale.

Significant weather alert

Significant weather alert map for the alert issued Saturday, August 12, 2017 | Map courtesy of the National Weather Service, St. George News

At about 12:45 p.m. National Weather Service Doppler radar indicated a strong thunderstorm over Bryce Canyon National Park, or 32 miles
west of Escalante, moving northeast at 5 mph.

Penny to nickel size hail and winds in excess of 40 mph will be possible.

Locations impacted include Bryce Canyon National Park, Tropic and Rubys Inn.

If threatening weather approaches, take shelter in a sturdy building.

Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. This alert is expected to last until 1:30 p.m.

Precautionary/Preparedness actions

“Turn around, don’t drown” when encountering flooded roads. Most flood deaths occur in vehicles.

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

Closely monitor weather forecasts and be prepared to take immediate action should heavy rain and flooding occur or a flash flood warning is issued.

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

  • Flash flood waves move at incredible speeds and 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 your group is 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.

During any flood emergency, stay tuned to your NOAA weather radio, commercial radio or television. Follow St. George News at STGnews.com and St. George News Facebook for weather alerts and updates relevant to the affected areas. Information from the National Weather Service and disaster and emergency services may save your life.

Email: news@stgnews.com

Twitter: @STGnews

Copyright St. George News, SaintGeorgeUtah.com LLC, 2017, all rights reserved.

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