Garrett’s Blog: Strong Winds, Uprooted Trees, Power Outages, Tornado Risk Monday Evening

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More active weather is expected on Monday evening with a complex of thunderstorms moving in during the late afternoon and early evening hours.

Unlike the last few storms, this complex will be moving into a highly unstable atomosphere. The risk of severe weather is much higher.

The complex of storms will arrive from Texas & Oklahoma sometime after 3pm and the severe threat will be over by 9pm.

Here are the main threats

  • Spin-Up Tornadoes along the leading edge of the squall line. Often times strong lines like this produce weak tornadoes in; usually in the EF0-EF2 range with winds from 70-120mph. A long lived wind damage event is likely. Depending on the spatial and temporal extent (how much real estate & how long it lasts) this could be considered a “Derecho” wind event.
  • Numerous uprooted trees. Soil saturation is at 100% with full leaf foliage. Any winds in excess of 40mph will be capable of downing trees. Winds may reach speeds of 70mph+ this evening causing widespread wind damage.
  • Flash Flooding. An additional 1-3″ of rain will fall this evening. Flash flooding is likely. Especially in SE Oklahoma and West Central Arkansas.
  • Hail. Temperatures above our heads are cooler and drier. We refer to this as a “steep lapse rate” hail growth will be a factor today. Possibly up to golfball size.

Locations: SE Oklahoma and SW Arkansas is at greatest risk for tornadoes (Waldron, Talihina, Poteau, Greenwood). The damaging wind risk will extend north into Fort Smith, Sallisaw, & Clarksville with the chance for spin-up tornadoes. In Northwest Arkansas the threat is somewhat lower, but the ‘comma head’ of the complex should pass directly over Fayetteville or Bentonville so there is at least enough wind shear for a low tornado risk; not as high as farther south.

Expect extended coverage on KXNW or Channel 5 this evening.

A Tornado Watch will likely be issued before 3pm for some parts of our area.

Here is how it looks graphically:

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This is Hi-Res Simulated Radar for 4pm Today. The timing has not been consistent on model runs. I think anytime between 3-7pm is fair game for the line to arrive. Once it’s established and organized in Oklahoma we should have a much better idea about the time of arrival.

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The black circle indicates the possibility of Significant Damaging Winds. This is the area that will have the most uprooted trees and power outages as well as the best tornado risk. It’s for most locations south of Fort Smith including SE Oklahoma and SE Arkansas.

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24-Hour Rainfall totals are expected to yield another 1-3″ of rain. This is probably the worst news. Flash Flooding will be likely and the already historic May rainfall totals are going to climb higher.

Stay weather aware and I’ll see you on 5NEWS or KXNW here in a few hours.

-Garrett