SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Thu Jun 10 2021 Valid 101200Z - 111200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL PLAINS... ...SUMMARY... Scattered severe storms are likely late this afternoon and evening across much of the northern and central Plains. All severe hazards are possible, including very large hail, 70+ mph wind gusts and a couple of tornadoes. ...Northern/Central Plains... Early-morning water-vapor imagery depicts a well-defined upper trough over northern CA. This feature is lifting northeast in line with latest model guidance that ejects the short wave into western MT/WY by 11/00z. Strong 500mb 12hr height falls will overspread the northern Plains after sunset as the trough subsequently moves into the western Dakotas by the end of the period. Lee surface cyclone is currently located near the northern Big Horn Mountains but should drift into southeast MT ahead of the short wave by late afternoon. Intense boundary-layer heating will be noted across the High Plains along the lee trough, and this will result in convective temperatures being breached by 22-23z. Ample boundary-layer moisture currently resides across the High Plains and strong buoyancy/instability will be available for intense updrafts as 500mb flow strengthens into the evening hours north of I-80. Earlier thoughts regarding convective initiation/evolution remain and only minor modifications have been made to the outlook, namely to extend higher severe probabilities south across the NE Panhandle. Latest HREF suggests a sharp southern edge to robust convection will be near the I-80 corridor. Forecast soundings across the NE Panhandle are very unstable with supercell profiles, as are soundings north across the western Dakotas into northeast MT. Supercells will develop along the lee trough/dryline by 22z near the international border, developing south into the central High Plains by 11/00z. Very large hail, potentially intense severe winds, and a few tornadoes are expected. This activity will propagate east ahead of the short wave during the overnight hours. Some consideration was given to higher severe probs due to the expected number of supercells that will develop within a favorable thermodynamic environment. This may be warranted in later outlooks. ...Elsewhere... Weak short-wave trough has topped the MB ridge and will dig southeast toward the upper Great Lakes region later today. This feature should encourage convection south of Lake Superior and hail/wind may be noted with storms as they propagate south-southeast ahead of the wave. A few severe wind gusts may also be noted within modest northwesterly flow across AR into northern LA along the back side of an early-day thunderstorm cluster. Afternoon heating may contribute to a few robust storms that will develop within a very unstable air mass characterized by high PW. A few thunderstorms may also develop along the dryline over west TX, as has occurred the last few days. Intense surface heating and slow-moving storms could produce an isolated severe wind gust/hail. ..Darrow/Bentley.. 06/10/2021 Read more LIVE: spc.noaa.gov
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