SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1229 AM CDT Thu Jul 15 2021 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN AND CENTRAL PLAINS INTO THE MID MISSISSIPPI VALLEY AND GREAT LAKES... ...SUMMARY... Isolated strong to severe storms may impact a corridor from the lower Great Lakes region into the mid Mississippi Valley and parts of the central/southern Plains today. Damaging wind gusts should be the main threat. ...Southern and Central Plains... An upper-level trough will move across the central Plains today. At the surface, a cold front is forecast to advance southward across Kansas. Surface dewpoints ahead of the front will be in the mid to upper 60s F. As surface temperatures warm, moderate instability is expected to be in place by afternoon, with MLCAPE reaching the 2000 to 2500 J/kg range in much of Oklahoma and southern Kansas. This, along with large-scale ascent associated with the upper-level trough, will aid thunderstorm formation near the front. Scattered thunderstorms are expected to develop and move east-southeastward across parts of Kansas, Oklahoma and the Texas Panhandle. In addition to the instability, 0-6 km shear is forecast to be near 25 kt along much of the front, suggesting that shear could be strong enough for a marginal severe threat. As low-level lapse rates become steepest during the mid to late afternoon, marginally severe wind gusts will be possible with the stronger multicells. The threat may persist into the early evening if a small cluster of strong thunderstorms can develop. ...Mid Mississippi Valley/Great Lakes... An upper-level trough will move eastward across the Upper Mississippi Valley today as west-southwesterly mid-level flow remains over much of the Great Lakes region. At the surface, a cold front will advance southeastward into the mid Mississippi Valley and southern Great Lakes. Surface dewpoints in the upper 60s and lower 70s F will result in the development of moderate instability ahead of the front. Thunderstorms should form and expand in coverage during the early afternoon as low-level convergence increases along the front. This convection is forecast to move eastward across north-central Missouri, central Illinois, northern Indiana and far northern Ohio during the afternoon. In addition to the instability, 0-6 km shear is forecast to be in the 20 to 25 kt range, mostly aided by speed shear in the mid-levels. The shear along with steep low-level lapse rates will make strong wind gusts possible with multicells that develop in the mid to late afternoon. ..Broyles/Wendt.. 07/15/2021 Read more LIVE: spc.noaa.gov
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