A hot, sunny day could lead to severe weather overnight in Siouxland

Weather News

SIOUX CITY, Iowa (KCAU) – It may seem sunny and hot today (July 8), but overnight into tomorrow morning, things could change as severe weather is possible overnight.

The Storm Prediction Center, or SPC, has upgraded the slight risk in far southwest Siouxland to an enhanced risk that hovers over central and south-central Nebraska and north-central Kansas.

Courtesy of Storm Prediction Center

This means the areas located in the enhanced risk could see numerous severe storms. Looking at current data from weather models, it’s looking like a typical bow echo system will be moving through the enhanced risk area.

However, a majority of Siouxland is located under a slight risk, which means Siouxland could see scattered severe storms. Siouxland is on the northern tip of the potential bow echo projected to move through central and south-central Nebraska overnight.

A bow echo is a type of mesoscale convective system, or MCS, that is shaped like an archer’s bow.

Courtesy of National Weather Service

Bow echos typically produce straight-line winds and occasionally tornadoes. The storm system tends to cause major damage from the straight-line winds.

This system is projected to move through the Siouxland metro area between 3 a.m. to around 7 a.m. Thursday morning. As the system progresses east over the I-29 corridor along the Nebraska and Iowa borders, the storms look to start breaking up; however, with that, it looks like another round of severe storms are possible around 9 a.m. and 10 a.m. Thursday morning.

Western Siouxland in Nebraska around Niobrara, Wayne, and Norfolk, severe weather may be moving in around 9 p.m. and 10 p.m. tonight (July 8).

The “second round” of severe storms stems from the bow echo decaying as it moves eastward, becoming a comma bow, which is creating a cluster of storms over Sioux City and northern Siouxland. The progression of the bow echo moving through Siouxland can be seen in the images below.

The main threats with both these storm systems, the bow echo and the cluster of storms from the bow echo, are going to be high winds and wind gusts exceeding 60 mph and large hail up to the size of a quarter possible. The threat for tornadoes is very low, but cannot be completely ruled out, especially in the enhanced risk area over central and south-central Nebraska.

After the system passes through the area, Siouxland could be left with some light lingering rain Thursday morning between 10 a.m. and 12 p.m.

The good thing about this system is Siouxland will get some much needed rainfall. Totals for rainfall by Thursday afternoon are looking to range from a half an inch to just over an inch the higher totals projected for northeast Siouxland. Sioux City is projected to see around three-fourths of an inch of rainfall up to an inch.

Rainfall totals are ranging from a half an inch to just under an inch and a half.

With two systems moving through parts of Siouxland, some areas may see severe weather during the first system, the bow echo, and some may not see severe weather until the second round of storms around 10 a.m. Thursday morning. Even though some areas may not see severe weather in both cases, or at all (like eastern and far northeastern Siouxland) it is still important to remember some important tips:

  • When thunder roars, head indoors.
    • Seek shelter in an interior room of a sturdy building if you are out and about when severe weather strikes.
  • Stay away from windows as debris or hail could break the window, causing injury.
  • Avoid contact with electrical equipment and water.
    • It’s best to unplug important electronic devices such as computers, cell phones that are charging/any electronic device charging, any important device you don’t want to fry if lightning were to strike or the power were to go out.
  • If you are swimming or planning to take a bath/shower, it is best to wait until after the storm because electricity moves through the water. If lightning were to strike your residence the electrical charges can travel through the water and cause injury or death in serious cases from electric shock.
  • Turn around, don’t drown.
    • If you find yourself out and about during severe weather or heavy rains, it is best to avoid driving through roadways or areas with standing or rushing water. It’s difficult to assess how fast the water is moving, how deep the water is, or even if the roadway has been washed away or not.
  • Always check social media or tune a weather radio to the local weather station for accurate updates.
  • NEVER seek shelter under a tree if you are outdoors.
    • Seek shelter in the nearest building or your vehicle.
  • NEVER seek shelter under an overpass if you are on the highway or interstate.
    • Overpasses and bridges are one of the most unsafe places to seek shelter as traffic will continue to move through the area and winds can create a vortex and pull you out from under the bridge/overpass.

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