15 Confirmed Tornadoes from Tuesday April 16th, 2024

On Tuesday, April 16th, a severe weather outbreak struck the state of Iowa, producing numerous tornadoes across the region. The National Weather Service has confirmed a total of 15 tornadoes as of Thursday April 18th, with damage ranging from mild to significant. Here’s a summary of the events and the impact of the tornadoes:

Tornado Details

• Adams County (9:31 AM – 9:33 AM): An EF-0 tornado touched down shortly after 9:30 AM near Carbon, Iowa. This tornado had peak winds of 80-mph and a path length of 1.75 miles, with a max width of approximately 30 yards.
• Cass County (9:58 AM – 10:00 AM): An EF-1 tornado touched down shortly before 10AM near Anita, Iowa. This tornado had peak winds of 90-mph and a path length of 0.64 miles, with an approximate width of 30 yards.
• Dallas County (11:05 AM): An EF-0 tornado touched down shortly after 11 AM and tracked from south to north across northern Dallas County. It had peak winds of 75-85 mph and a path length of 6.8 miles with a maximum width of approximately 50 yards. The tornado was on the ground for roughly five minutes.
• Plymouth County (1:46 PM): An EF-U tornado occurred near Hinton, Iowa at 1:46 PM.
• Plymouth County (1:58 PM – 2:00 PM): An EF-1 tornado occurred near Le Mars, Iowa from 1:58 PM to 2:00 PM. It had peak winds of 100 mph, a maximum path length of 1.32 miles, and a maximum width of 25 yards. An outbuilding was destroyed, with debris spreading northeast of the damage location. The tornado then produced tree damage before lifting.
• Sioux County (2:11 PM): An EF-U tornado occurred near Struble, Iowa around 2:11 PM, touching down 2 miles north of Struble.
• Calhoun County (2:26 PM – 2:38 PM): An EF-1 tornado occurred near Rockwell City from 2:26 PM through 2:38 PM. It had estimated peak winds of 100 mph, a path length of 6.12 miles, and a maximum width of 75 yards.
• Sioux County (2:28 PM – 2:29 PM): An EF-0 tornado occurred near Sioux Center from 2:28 PM to 2:29 PM. It had peak winds of 85 mph, a maximum path length of 0.89 miles, and a maximum width of 25 yards. The tornado touched down around 2:28 PM 2 miles NNW of Sioux Center, Iowa. This short-lived tornado was captured by a nearby spotter, and damage was limited to a collapsed barn and some trees at a farmstead.
• Calhoun County (2:57 PM – 2:59 PM): An EF-U tornado occurred near Manson from 2:57 PM through 2:59 PM. Due to it not causing any damage, the peak winds are unknown. It had a path length of 0.63 miles and a maximum width of approximately 30 yards.
• Lyon County (2:59 PM – 3:00 PM): An EF-1 tornado occurred south of George, Iowa in Lyon County from 2:59 PM to 3:00 PM. It had peak winds of 100 mph, a length of 0.65 miles, and a maximum width of 25 yards. The tornado touched down around 2:59 PM, 4 miles west-northwest of Matlock, Iowa. A narrow path of damage was reported across a golf course into a farmstead immediately to the north.
• Buchanan County (3:02 PM – 3:15 PM): An EF-1 tornado hit near Quasqueton and Winthrop, Iowa. It had max winds of 110 mph, a path length of 10.48 miles, and a maximum width of 125 yards. There were numerous large trees uprooted or snapped, including near the Pine Creek Cemetery. A farm outbuilding was damaged, along with an overturned semi on U.S. Highway 20.
• Pocahontas County (3:11 PM – 3:16 PM): The first EF-U tornado in Pocahontas County occurred near Palmer from 3:11 PM through 3:16 PM. It had a path length of 2.05 miles and a maximum width of 50 yards.
• Pocahontas County (3:34 PM – 3:38 PM): The second EF-U tornado in Pocahontas County occurred near Rolfe from 3:34 PM through 3:38 PM. It had a max length of 1.66 miles and a max width of approximately 40 yards.
• Pocahontas County (3:42 PM – 3:45 PM): An EF-0 tornado occurred on the east side of Rolfe from 3:42 PM through 3:45 PM. It had estimated peak winds of 70 mph, a path length of 0.64 miles, and a maximum width of 40 yards.
• Henry/Lee Counties (4:25 PM – 5:21 PM): The strongest tornado of the day was an EF-2 that caused damage in the towns of Salem and New London. It had estimated peak winds of 130 mph, a path length of 42.03 miles, and a maximum width of 600 yards. One home north of New London had collapsed exterior walls, a roof lost, and a garage destroyed.

Continuing Surveys

The National Weather Service will continue to survey damage and gather data from satellite and radar sources in the coming days. This may lead to updates in the tornado count and further assessments of the damage caused by the storms.

While most of the tornadoes were weak and brief, the tornadoes did cause damage in some areas, particularly in far southeast Iowa.

What is an EF-Unknown?

An EF-Unknown tornado is a classification used when the strength or damage of a tornado cannot be accurately assessed. The Enhanced Fujita (EF) scale, which is used to measure the intensity of a tornado, ranges from EF0 (weakest) to EF5 (strongest) based on the damage the tornado inflicts on structures and vegetation.

When a tornado occurs and the damage is too minimal, ambiguous, or the affected area is inaccessible (e.g., due to flooding or other hazards), meteorologists may classify it as EF-Unknown. This classification may also occur if there is insufficient data or if the tornado’s path is not well-defined. In such cases, it can be challenging to assign an appropriate EF scale rating.

While EF-Unknown tornadoes are less common, they serve as a reminder of the importance of thorough storm assessments and the challenges meteorologists face when categorizing these powerful weather events.

Photo: ISCN Storm Chaser Willard Sharp