Scattered strong to severe storms are expected today mainly across the Upper Mississippi Valley and the Central/Northern Plains. Damaging winds and large hail are possible.

Locations:

  • Primary Risk Area: Northern/Central Plains
  • Secondary Risk Area: Southern High Plains.

Threats:

  • Damaging Winds: Primarily across the Upper Mississippi Valley and Northern/Central Plains.
  • Large Hail: Likely in the Central High Plains and Northern Plains.
  • Tornadoes: A tornado or two are possible in the Central Plains (SW Nebraska mainly).

Timing:

  • Storm Initiation: Late afternoon in the Central High Plains.
  • Peak Threat: Afternoon into evening.
  • Storm Weakening: Overnight, as storms move east.

Discussion:

 

Northern/Central Plains:

  •  Setup: A pronounced mid/upper-level trough over the Pacific Northwest will move east-northeast over the Northern Intermountain region today, reaching the Northern High Plains tonight. Surface cyclogenesis will occur across interior Wyoming, extending into the Central High Plains near a southwest/northeast-oriented front.
  • Storm Development: Strong boundary-layer heating across eastern Colorado into northwest Kansas and southwest Nebraska will breach convective temperatures, leading to isolated supercell development. This activity is most probable near/east of the northeast Colorado surface low and triple point vicinity, including the Colorado/Nebraska/Kansas border region.
  • Severe Potential: Ample MLCAPE (2500-4000 J/kg) with steep lapse rates and favorable shear will support sustained rotating updrafts. Very large hail may accompany these storms, with some tornado threat also possible. Storms are likely to persist east-northeastward, potentially clustering/organizing toward central Nebraska this evening.
  • Northern Extent: Strong dynamic forcing will encourage convection across the High Plains of northeast Wyoming and southeast Montana ahead of the surging cold front. This activity will spread northeast into the Dakotas overnight, aided by a substantial increase in the south-southwesterly low-level jet. The severe threat will shift into the Upper Red River Valley late tonight.

Southern High Plains:

  • Shear is Favorable: Shear in this part of the world will be pretty favorable (0-6km shear over 30kts). This may lead to a storm that forms acquiring supercell characteristics as it moves east/south.
  • Hot, dry in lower levels: The thing preventing a more robust severe weather threat are hot and dry low levels. This will lead to relatively high-based storms that will have a tendency for strong pushes of outflow, which should cut off any attempts at low level mesocyclones.
  • Storm Coverage Limited: It is unlikely storms will be numerous today. But there exists an outside chance of some models for scattered storms down the dryline that will need to be watched. This can result in funky storm interactions which could yield a surprise.