A very strong upper trough of low pressure will be shifting eastward through the western U.S. today. By mid-afternoon, strong jet stream level winds will be overspreading the Plains. In response to the upper system, a deep surface low pressure area will organize over Nebraska. A strong cold front will be surging southward through the high Plains, and in typical fashion – a dryline will extend from the surface low – southward into western Texas.
Low level moisture has been increasing in the warm sector over the past 24 hours. While the depth and quality of this moisture will come well short of what is usually needed for a major outbreak of severe thunderstorms, it will no doubt be sufficient for some.
The vertical wind shear profiles are forecast to be quite impressive, well above levels capable of generating and sustaining rotating updrafts. Low level shear would support tornado production, if the quality of moisture was better.
As it is, thunderstorms are expected to form near and east of the dryline from Nebraska to western Oklahoma during the late afternoon hours. Some of these storms will quickly become severe, producing large hail and damaging winds as they shift northeastward. An isolated tornado occurrence is not out of the question.
Most of the severe events are expected to be marginal, however, there will be a few significant events / winds over 70 mph and hail to golfball size /.
The cold front will enter northwest Oklahoma by daybreak Sunday, and spread across the state during the day. By Sunday night, temperatures in the Okarche area should drop into the upper 20′s.