Risk for hail, damaging winds increases for Monday storms in Sioux Falls area

Update as of 10 a.m. Monday: Multiple rounds of severe weather remain possible for Monday in the Sioux Falls area, according to NWS and the agency's latest prediction as of Monday morning.

Parts of southern Lincoln County will be under an excessive heat warning from 1 to 8 p.m., the NWS stated.

"High heat and humidity across the region will lead to heat index values up to around 110 degrees thisafternoon," the NWS stated in its latest weather briefing. "Scattered to areas of severe thunderstorms are possible at times from this afternoon and into the overnight hours."

Compared with predictions Sunday night for Monday, the outlook for severe weather has slightly increased in scope ahead of the round of storms, both in timing and type of risk, the NWS states.

There is now an enhanced risk for hail in 2 inches in diameter or more as well as 75-mph winds of more. The risk of a few tornadoes being possible also remains at slight. And there's an increasing risk for isolated flash flooding, the NWS stated Monday morning.

"Each round of thunderstorms will be capable of producing 1-2 inches of rain in an hour," the NWS stated.

As for timing of the storms, severe weather could start developing as early as 2 p.m. Monday and last through the early overnight hours Tuesday. The most likely timing remains between 4 p.m. and 1 a.m.

"The larger timescale is due to considerable variance across model solutions," the NWS stated. "Confidence is highest in the late evening and overnight storms occurring, though the early to late afternoon storms cannot be ruled out."

The NWS is expected to provide another update late Monday morning or early afternoon. Exact timing is unclear.

Earlier story : The Sioux Falls area may be in for some late-afternoon to late-night severe weather Monday, according to the National Weather Service.

While the area will remain under a heat advisory from 1 to 8 p.m. Monday, strong storms bringing the possibility of large hail, damaging winds and even a few tornadoes are expected to move through between 4 p.m. and 1 a.m., with the highest risk between 5 p.m. and about 10 or 11 p.m., according to the NWS.

"Severe storms are expected to evolve within a zone extending from the northern/central High Plains eastward to Wisconsin Monday afternoon into the nighttime hours," according to a statement from the NWS Storm Prediction Center. "Large to very large hail, and swaths of severe, potentially damaging, gusts are expected, especially across South Dakota into Minnesota. A few severe storms producing strong gusts and hail are also expected across southern New England."

That kind of anticipated late-summer activity has captured the attention of renowned storm chaser Reed Timmer, who announced on social media Sunday he would be headed to South Dakota to capture the outcome.

As of the latest update from NWS at 4:30 p.m. Sunday, meteorologists' confidence in the exact timing of the storms was still low, while condience in what kind of severe storms might roll through the area was "only moderate."

The NWS described two likely scenarios in that update, but suggested the actual weather event may unfold in a scenario somewhere in between.

What are the scenarios?

Scenerio No. 1:

The NWS predicts there could be two rounds of storms that develop, with the first in the afternoon and evening in southwestern Minnesota. The second rounds could move in during the evening and overnight hours from central South Dakota.

Scenario No. 2:

The initial round is expected to hit in the afternoon hours, directly over the Sioux Falls area, and the storms are expected to be stronger and move through the area faster than the second round. The second round would hit during the evening hours and would not be as impactful, the NWS stated.

What's the overall risk?

The NWS states large hail of 2 inches or more in diamater, along with 70 mph winds or more, heavy rain and a few tornadoes are possible with this storm system.

Stay with the Argus Leader and refresh this page for the latest on Monday's developing storms.

This article originally appeared on Sioux Falls Argus Leader: Risk for hail, damaging winds increases for Monday storms in Sioux Falls area