SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Tue Aug 24 2021 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... A few marginally severe thunderstorms are expected today from parts of the central and northern Plains into the upper Mississippi Valley. Hail and strong gusty winds should be the primary threats. ...Central and Northern Plains/Upper Mississippi Valley... West northwest mid-level flow will be in place today from the northern Plains eastward into the upper Mississippi Valley. An MCS along with an isolated wind-damage threat should be ongoing at the start of the period. If the MCS can hold together, the line of storms will move east-southeastward into the western Great Lakes around midday. Further to the west, a cold front will advance southeastward from the Dakotas into the central Plains. Moderate to strong instability appears likely to develop ahead of the front and to the south of the MCS track from southern and eastern Nebraska into Iowa and Illinois. As a shortwave trough approaches from the west this afternoon, isolated to scattered convective development will be possible along and ahead of the front. Although model spread is large, the NAM scenario seems reasonable with a cluster of storms forming in central and northeastern Nebraska. This cluster could grow upscale and move across Iowa during the evening. RAP forecast soundings by 00Z/Wednesday at Des Moines and Omaha have MLCAPE near 2500 J/kg with 0-6 km shear from 20 to 25 kt. This environment would support multicells capable of producing strong wind gusts and hail. Deep-layer shear is a bit stronger in central Nebraska, where a supercell can not be ruled out. However, model spread is large concerning the distribution of instability. For this reason, uncertainty is considerable for this outlook update. For this reason, will maintain a marginal risk across much of the north-central U.S. ..Broyles/Moore.. 08/24/2021 Read more LIVE: spc.noaa.gov
http://dlvr.it/S6CYgr
