• Strong thunderstorms are expected throughout western Utah on Wednesday
  • The NWS warned of flash flooding in several national parks in the state
  • Hikers have been asked not to go to these places

Severe weather conditions are expected in parts of Utah, especially in the northwestern region, and Arizona, the National Weather Service (NWS) has warned.

Flood watches were issued across Utah, including in its south-central parts, as excessive rainfall was expected through Wednesday evening.

The NWS in Salt Lake City said strong thunderstorms are expected across "much of Western Utah" from afternoon through evening. It added the northwestern region will see the "highest threat" of thunderstorms.

Flash floods are also expected near some national parks in southern Utah, including the Capitol Reef National Park, Zion National Park, Bryce Canyon National Park and Glen Canyon National Recreation Area.

Officials have warned people not to go on hiking in these parks while the severe weather threat alert remains in effect.

In its short-range forecast discussion report issued Tuesday, the NWS Weather Prediction Center (WPC) said "intense rainfall rates could lead to scattered flash floods" Wednesday evening in the Four Corners – a region of the Southwestern U.S. that includes the southeastern corner of Utah.

Flood watch effective from Tuesday evening through Wednesday evening:

  • Central Mountains
  • San Rafael Swell
  • Castle Country
  • Capitol Reef National Park and vicinity
  • Wasatch Plateau/Book Cliffs
  • Western Canyonlands
  • Lake Powell
  • South Central Utah

Flood Watch effective from Wednesday morning through Wednesday evening:

Flood Watch effective through Thursday evening:

  • Arches/Grand Flat
  • Natural Bridges
  • Abajo Mountains
  • La Sal Mountains
  • Southeast Utah

Flood Watch effective from Tuesday evening through Thursday evening:

  • Tavaputs Plateau

Forecasters are also expecting flash flooding in the neighboring state of Arizona.

The NWS office in Phoenix said chances of rain will gradually increase "heading into Wednesday night." It previously warned that scattered showers and lightning were possible Tuesday evening.

Flood watches in Arizona:

From Tuesday evening through Wednesday evening:

  • White Mountains of Greenlee and Graham Counties
  • Eastern Cochise County below 5,000 feet

Effective through Wednesday evening:

  • Kaibab Plateau
  • Marble Canyons
  • Glen Canyons
  • Coconino Plateau
  • Grand Canyon Country

Effective through Thursday evening:

  • Eastern Mogollon Rim
  • Little Colorado River Valley
  • Black Mesa Area
  • Defiance Plateau
  • Chuska Mountains
  • Chinle Valley
  • Mesas Hwy 264 Northward
  • Yavapai County Mountains
  • Sycamore Canyons
  • Oak Creek
Utah flash flood_2
Construction equipment clear debris after a flash flood in Hildale, Utah, on Sept. 15, 2015. Reuters/David Becker