Day 3 Convective Outlook
Issued: · Valid: –
Summary
Scattered severe thunderstorms are expected across the central High Plains on Tuesday, with isolated severe storms possible into the Upper Mississippi Valley. These storms may produce large to very large hail and damaging wind gusts.
Product Text
000 ACUS03 KWNS 211917 SWODY3 SPC AC 211916 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Sun Jun 21 2026 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe storms are expected across the central High Plains on Tuesday with isolated severe storms possible into the Upper Mississippi Valley. Large to very large hail and damaging wind gusts will be the primary threats. ...Synopsis... An upper low initially over Saskatchewan/Manitoba will drift southeast to along the international border with an attending belt of 40-50+ kt mid-level flow forecast across the northern and central Plains into the upper Midwest. Farther east, a short-wave trough trailing an upper low over Ontario will move through the Mid-Atlantic. In the low levels, an area of low pressure is forecast to develop from the northern Plains into upper MS Valley with a trailing boundary extending southwest into the central High Plains. Elsewhere, a cold front will move off the Mid-Atlantic Coast with the trailing extension of the boundary moving into the Southeast. ...Central and southern High Plains... Despite the potential for early-day storms across portions of NE, TX, and OK, the EML is expected to remain intact over the central High Plains. When coupled with an increasingly moist upslope air mass in the vicinity of the front, moderate to strong instability is forecast by afternoon. Diurnally enhanced thunderstorms are expected to form along favored terrain and pre-existing surface boundaries amidst a kinematic environment featuring vertically veering winds with height with sufficient vertical shear to support supercells capable of large to very large hail. The nocturnal strengthening of a low-level jet over western parts of KS, OK, and TX may favor upscale growth of storms into a forward-propagating MCS Tuesday evening with an associated increase in severe-wind-gust potential. ...Upper Mississippi Valley into the mid Missouri Valley... Latest model data are in good agreement in depicting areas of showers and storms lingering through much of the day across the pre-frontal warm sector. Vertical shear is forecast to be sufficiently strong to support organized storm modes, especially across the upper MS Valley. However, the potential for clouds and precipitation to limit air mass destabilization leads to uncertainty in the extent of the severe-weather threat. As such, the low severe-weather probabilities will be maintained with this forecast update. ...Middle and southern Atlantic Coast into the central Gulf Coast States... A few strong storms capable of gusty winds appear possible Tuesday afternoon along and ahead of the synoptic front. While poor low/mid-level lapse rates are expected to limit a more robust damaging-wind threat, low severe-weather probabilities may eventually be added once details in storm evolution become more clear. ..Mead.. 06/21/2026 $$